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Reproductive System Overview - Anatomy & Physiology

2009-04-15T22:26:04Z

Katherine: /* Overview of the Reproductive system */

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== Overview of the Reproductive system ==
Reproduction is the complex set of biological processes that result in the formation of a new organism. It is crucial, especially in our production animals, that we understand how these processes occur normally. Pathology and disease are common within the reproductive system and can not only lead to a sick animal but also lead to loss of production. In this section we hope to cover all the main processes in the domestic animals. This will lay a foundation to aid in the understanding of more potentially quite complex pathologies.

* [[Overview of the Reproductive System - Overview of Reproductive Hormones - Anatomy & Physiology| Overview of Reproductive Hormones ]]
----

== Puberty ==

* [[Puberty- Overview of Puberty - Anatomy & Physiology|Overview of Puberty]]
* [[Puberty - Defining Puberty - Anatomy & Physiology|Defining Puberty]]
* [[Puberty - Endocrine Events of Puberty - Anatomy & Physiology|Endocrine Events of Puberty]]
* [[Puberty - Differences in the Male and Female Hypothalamus- Anatomy & Physiology|Differences in the Male and Female Hypothalamus]]
* [[Puberty - Factors Influencing the Onset of Puberty - Anatomy & Physiology|Factors Influencing the Onset of Puberty]]

----

== Female Reproductive Tract ==

* [[Female Reproductive Tract -The Ovary - Anatomy & Physiology|The Ovary]]

* [[Female Reproductive Tract -The Oviduct - Anatomy & Physiology|The Oviduct]]

* [[Female Reproductive Tract -The Uterus - Anatomy & Physiology|The Uterus]]

* [[Female Reproductive Tract -The Cervix - Anatomy & Physiology|The Cervix]]

* [[Female Reproductive Tract -The Vagina/Vestibule - Anatomy & Physiology|The Vagina and External Genitalia]]

* [[Female Reproductive Tract -Oestrous Cycle - Anatomy & Physiology|Oestrous Cycle]]

* [[Female Reproductive Tract -Seasonality of Reproduction - Anatomy & Physiology|Seasonality of Reproduction]]

----

== Male Reproductive Tract ==

* [[Male Reproductive Tract -The Testes and Epididymis - Anatomy & Physiology|The Testes and Epididymis]]

* [[Male Reproductive Tract -Accessory Sex Glands - Anatomy & Physiology|Accessory Sex Glands]]

* [[Male Reproductive Tract -The External Genetalia - Anatomy & Physiology|The Penis]]

* [[Male Reproductive Tract -Spermatogenesis and Spermiation - Anatomy & Physiology|Spermatogenesis and Spermiation]]

* [[Male Reproductive Tract -Useful Terms - Anatomy & Physiology|Useful Terms]]

----

== Reproductive Behaviour ==

* [[Reproductive Behaviour - Overview of Reproductive Behaviour - Anatomy & Physiology|Overview of Reproductive Behaviour]]
* [[Reproductive Behaviour - Nervous Pathway Eliciting Reproductive Motor Behaviour - Anatomy & Physiology|Nervous Pathway Eliciting Reproductive Motor Behaviour]]

=== Male ===

* [[Reproductive Behaviour - Pre-copulatory Behaviour - Anatomy & Physiology|Pre-copulatory Behaviour]]

* [[Reproductive Behaviour - Copulatory Behaviour - Anatomy & Physiology|Copulatory Behaviour]]

* [[Reproductive Behaviour - Post-Copulatory Behaviour - Anatomy & Physiology|Post-Copulatory Behaviour]]

=== Female ===

* [[Reproductive Behaviour - Oestrus Behaviour - Anatomy & Physiology|Oestrus Behaviour and Methods of Oestrus Detection]]

* [[Reproductive Behaviour - Attractivity Behaviour - Anatomy & Physiology|Attractivity Behaviour]]

* [[Reproductive Behaviour - Proceptivity Behaviour - Anatomy & Physiology|Proceptivity Behaviour]]

* [[Reproductive Behaviour - Receptivity Behaviour - Anatomy & Physiology|Receptivity Behaviour]]

* [[Reproductive Behaviour - Maternal Behaviour - Anatomy & Physiology|Maternal Behaviour]]

* [[Reproductive Behaviour - Nursing Behaviour - Anatomy & Physiology|Nursing Behaviour ]]

----

== Fertilisation, Implantation and Early Embryonic Development ==

* [[Copulation -Sperm in the Female Tract - Anatomy & Physiology|Sperm in the Female Tract]]

* [[Fertilisation, Implantation and Early Embryonic Development -Fertilisation- Anatomy & Physiology|Fertilisation]]

* [[Fertilisation, Implantation and Early Embryonic Development -Embryonic Development of the Blastocyst- Anatomy & Physiology|Embryonic Development of the Blastocyst]]

* [[Fertilisation, Implantation and Early Embryonic Development -Implantation- Anatomy & Physiology|Implantation]]

* [[Fertilisation, Implantation and Early Embryonic Development -Sexual Differentiation- Anatomy & Physiology|Sexual Differentiation]]

* [[Male Reproductive Tract -Internal and External Genitalia Development - Anatomy & Physiology|Internal and External Genitalia Development]]
----

== Gestation ==

* [[Gestation -Reference Table of Gestation Lengths in Various Species - Anatomy & Physiology|Reference Table of Gestation Lengths in Various Species]]

* [[Gestation -Diagnosis of Pregnancy - Anatomy & Physiology|Diagnosis of Pregnancy]]

* [[Gestation -Maternal Recognition of Pregnancy - Anatomy & Physiology|Maternal Recognition of Pregnancy]]

*[[Gestation -Litter Sizes - Anatomy & Physiology|Litter Sizes]]

* [[Gestation -Placenta - Anatomy & Physiology|Placenta]]

* [[Gestation -Maintaining Pregnancy - Anatomy & Physiology|Maintaining Pregnancy]]

----

== Parturition ==

* [[Parturition - Normal Parturition - Anatomy & Physiology|Normal Parturition ]]

* [[Parturition - Endocrine Control of Parturition - Anatomy & Physiology|Endocrine Control of Parturition]]

*[[Parturition - Pharmacological Manipulation of Parturition - Anatomy & Physiology|Pharmacological Manipulation of Parturition ]]

* [[Parturition - Risks in Parturition - Anatomy & Physiology|Risks in Parturition]]

----

== The Puerperium ==

* [[The Puerperium - Overview of the Puerperium - Anatomy & Physiology|Overview of the Puerperium]]

* [[The Puerperium - Myometrial Contraction and Expulsion of Lochia - Anatomy & Physiology|Myometrial Contraction and Expulsion of Lochia]]

* [[The Puerperium - Endometrial Repair- Anatomy & Physiology|Involution & Endometrial Repair]]

* [[Female_Reproductive_Tract_-The_Ovary_-_Anatomy_%26_Physiology#Processes_Taking_Place_In_The_Ovary|Resumption of Ovarian Function]]: for more information see 'Species Differences in the Puerperium' below.

* [[The Puerperium - Elimination of Bacterial Contamination of the Reproductive Tract- Anatomy & Physiology|Elimination of Bacterial Contamination of the Reproductive Tract]]

* [[The Puerperium - Factors Influencing the Puerperium- Anatomy & Physiology|Factors Influencing the Puerperium]]

* [[The Puerperium - Species Differences in the Puerperium- Anatomy & Physiology| Species Differences in the Puerperium]]

----

== Lactation ==

* [[Lactation - Overview of Lactation - Anatomy & Physiology|Overview of Lactation]]

* [[Lactation - The Mammary Gland - Anatomy & Physiology|The Mammary Gland]]

* [[Lactation - Endocrine Control - Anatomy & Physiology|Endocrine Control]]

* [[Lactation - Milk Composition and Biosynthesis- Anatomy & Physiology|Milk Composition and Biosynthesis]]

* [[Lactation - Involution - Anatomy & Physiology|Involution]]

* [[Lactation - Links to Associated Pathology - Anatomy & Physiology|Links to Associated Pathology]]

----

== Reproductive Technologies ==

* [[Reproductive Technologies -Semen Collection - Anatomy & Physiology|Semen Collection]]

* [[Reproductive Technologies -Artificial Insemination - Anatomy & Physiology|Artificial Insemination]]

* [[Reproductive Technologies -Multiple Ovulation and Embryo Transfer- Anatomy & Physiology|Multiple Ovulation and Embryo Transfer]]

* [[Reproductive Technologies -In Vitro Fertilization- Anatomy & Physiology|In Vitro Fertilization]]

* [[Reproductive Technologies -In Vitro Maturation- Anatomy & Physiology|In Vitro Maturation]]

* [[Reproductive Technologies -Intracytoplasmic Sperm Injection- Anatomy & Physiology|Intracytoplasmic Sperm Injection]]

* [[Reproductive Technologies -Embryo Sexing- Anatomy & Physiology|Embryo Sexing]]

* [[Reproductive Technologies -Semen Sexing- Anatomy & Physiology|Semen Sexing]]

* [[Reproductive Technologies -Embryo Splitting- Anatomy & Physiology|Embryo Splitting]]

* [[Reproductive Technologies -Nuclear Transplantation:Cloning- Anatomy & Physiology|Nuclear Transplantation:Cloning]]

* [[Reproductive Technologies -Transgenic Animals- Anatomy & Physiology|Transgenic Animals]]

----

== Camelids (LLamas & Alpacas) ==

* [[Camelids (LLamas & Alpacas) - Female Anatomy - Anatomy & Physiology|Female Anatomy]]
* [[Camelids (LLamas & Alpacas) - Male Anatomy - Anatomy & Physiology|Male Anatomy]]
* [[Camelids (LLamas & Alpacas) - Breeding Cycle - Anatomy & Physiology|Breeding Cycle]]
* [[Camelids (LLamas & Alpacas) - Mating - Anatomy & Physiology|Mating]]
* [[Camelids (LLamas & Alpacas) - Pregnancy Diagnosis - Anatomy & Physiology|Pregnancy Diagnosis]]
* [[Camelids (LLamas & Alpacas) - Parturition - Anatomy & Physiology|Parturition]]
* [[Camelids (LLamas & Alpacas) - Lactation & Care of the Newborn - Anatomy & Physiology|Lactation & Care of the Newborn]]

----

== Small Domestic Mammals ==

* [[Small Mammals -Reference Table of Reproductive Characteristics for Small Domestic Mammals- Anatomy & Physiology|Reference Table of Reproductive Characteristics for Small Domestic Mammals]]
* [[Small Mammals -Guinea Pig- Anatomy & Physiology|Guinea Pig]]
* [[Small Mammals -Ferret- Anatomy & Physiology|Ferret]]
* [[Small Mammals -Chinchilla- Anatomy & Physiology|Chinchilla]]
* [[Small Mammals -Chipmunk- Anatomy & Physiology|Chipmunk]]
* [[Small Mammals -Mouse- Anatomy & Physiology|Mouse]]
* [[Small Mammals -Hamster- Anatomy & Physiology|Hamster]]
* [[Small Mammals -Rabbit- Anatomy & Physiology|Rabbit]]
* [[Small Mammals -Rat- Anatomy & Physiology|Rat]]
* [[Small Mammals -Gerbil- Anatomy & Physiology|Gerbil]]

----

== Exotics ==

* [[Exotics - Avian Reproductive Anatomy and Physiology - Anatomy & Physiology|Avian Reproductive Anatomy and Physiology ]]

* [[Exotics - Reptile Reproductive Anatomy and Physiology - Anatomy & Physiology|Reptile Reproductive Anatomy and Physiology]]

* [[Exotics - Amphibian Reproductive Anatomy and Physiology - Anatomy & Physiology|Amphibian Reproductive Anatomy and Physiology]]

* [[Exotics - Fish Reproductive Anatomy and Physiology - Anatomy & Physiology|Fish Reproductive Anatomy and Physiology ]]

== References ==

* P.L Senger: Pathways to Pregnancy and Parturition,2nd Edition
* David E. Noakes,Timothy J. Parkinson,Gary C. W. England,Geoffrey H. Arthur: Arthur's Veterinary Reproduction and Obstetrics
* Bairbre O'Malley:Clinical Anatomy and Physiology of Exotic Species
* Dyce, Sack and Wensing: Textbook of Veterinary Anatomy, 3rd Edition
* Konig and Liebich: Veterinary Anatomy of Domestic Mammals, 3rd Edition
* Victoria Aspinall, Melanie Cappello: Introduction to Veterinary Anatomy & Physiology
* Gina Bromage: Llamas and Alpacas: A Guide to Management
* R.J. Roberts,Lydia Brown: Aquaculture for Veterinarians - Fish Husbandry and Medicine (Pergamon Veterinary Handbook)
* B.Young, J.W Heath: Wheater's Functional Histology, A Text and Colour Atlas

== Creators of Reproductive Anatomy and Physiology Pages ==

* Amy Cartmel (RVC)
* [[Lois_Wilkie|Lois Wilkie]] (RVC)

Canine Phalanges - Anatomy & Physiology

2008-09-11T15:21:17Z

Katherine: /* Phalanges */

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Dogs are '''digitigrade''' animals; this means that the weightbearing surface of their limbs is their digit. The canine phalanges are thus very important. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* They are rod shaped bones, numbered from I to V. The 1st is the most medial and is very small, the 3rd and 4th are the longest.
* The proximal base articulates with it's corresponding carpal bone and the adjacent metacarpal.
* The distal end is it's head, which is transversely cylindrical and articulates with the proximal phalanx.
* Metacarpals II - V possess a sagittal ridge on their palmar aspects.

====Phalanges====

* Proximal phalanx - of the main digits (II - V) they have a concave articular surface proximally. The palmar border has a groove to accomodate the articular surface of the metacarpus when the joint is fixed. The distal head has two convex areas seperated by a groove.
* Middle phalanx - roughly two-thirds the length of the proximal, its base has a sagittal ridge on the articular surface, which articulates with the groove of the proximal phalanx. The head resembles that of the proximal.
* Distal phalanx - made up of a cone-shaped ungual process with a distinct collar, '''ungual crest'''. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw. It articulates with the middle phalanx via a small sagittal crest.
* A bony sesamoid bone is found on the dorsal aspect of the metacarpophalangeal joint.
* The 'dew claw', metacarpal I, is normally present in the forelimb but often not in the hindlimb. It normally only consists of two phalanges that resemble the proximal and distal ones.

==Joints==

====Metacarpophalangeal Joint====

* Movement - flexion and extension.
* Each joint, bar the first digit, has a pair of sesamoid bones associated with the palmar aspect of the joint. They articulate with a concave area of the proximal phalanx.
* The joint capsule runs between the four bones of the joint. Dorsally it extends under the extensor tendon, this part also intermingles with with an expanding area of the common digital extensor tendon. Distally it binds to the articular cartilage of the proximal phalanx and on the palmar aspect its dorsal attachment is level with the proximal end of the sesamoid bones.
* '''Collateral ligaments''' - bind the the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone.
* '''Palmar/intersesamoidean ligament''' - a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx.
* '''Distal sesamoid ligaments''' - a collection of ligaments that aren't well developed in the dog. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. They include the cruciate and short ligaments.
* The '''superficial transverse metacarpal ligaments''' surround the flexor tendons and their sheaths at the point of the sesamoid ligaments.
* The '''distal annular ligaments''' cross the surface of the flexor tendons and sheaths at the level of the proximal and middle phalanx.

====Proximal Interphalangeal Joint====

* Movement - flexion and extension.
* The joint capsule attaches near the articular surfaces of the proximal and middle phalanges. It extends slightly in a pouch dorsally and more extensively on the palmar aspect. The dorsal capsule is reinforced by a fibrocartilaginous nodule; the extensor tendon attaches to the capsule here.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal Joint====

* Movement - extension, slight flexion.
* The joint capsule attaches to the articular periphery of the bones and has a small fibrocartilagenous bead in the palmar aspect.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the ungual crest of the distal phalanx.
* '''Dorsal ligament''' - connects the proximal dorsal border of the extensor process of the distal phalanx. These are paired in dogs and function is to keep the claw raised until contraction of the deep digital flexor acts to overcome their tension.

==Musculature==

'''Interosseous'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones.
* Insertion - sesamoid bones of the metacarpophalangeal joint, it then continues as extensor branches that wrap round the dorsal aspect of the digit to join the extensor tendons.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - palmar aspect of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - palmar aspect of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - extensor process, distal phalanx

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - proximal phalanx

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - flexor aspect of the tarsus and branches which continue onto the extensor process of each of the distal phalanges.
* It divides into four branches at the level of the tarsus and are bound by the fibrous transverse bands of the proximal and distal retinaculum and are enclosed by a common synovial sheath.

'''Lateral Digital Extensor'''
* Origin - proximal fibula and lateral collateral ligament of the stifle.
* Insertion - It joins to the tendon of the long digital extensor to insert on the distal phalanx of the 5th digit.

'''Long Extensor of the first digit'''
* Origin - Proximal fibula
* Insertion - the metatarsophalangeal joint of the 2nd and 1st digit.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur and is firmly united to the lateral head of the gastrocnemius.
* Insertion - Middle phalanx of the 2nd to 5th digits.
* The muscle belly converges into a strong tendon at mid-tibial level and runs medially to the gastrocnemius to the point of the hock forming a broad cap. This cap is held in place by medial and lateral retinaculae.
* A '''synovial bursa''' lies between this cap and the calcaneal tuberosity.
* It then runs over the plantar aspect of the hock and splits twice at the level of the dorsal tarsal bones, thus forming it's four branches for insertion.

'''Deep Digital Flexor'''
* This muscle consists of three seperate heads; the '''caudal tibial muscle''', the '''lateral digital flexor muscle''' and the '''medial digital flexor muscle'''.
* '''Lateral digital flexor'''
** Origin - caudal surface of the tibia and fibula
** Insertion - its strong tendon fuses with that of the medial digital flexor tendon on the plantar aspect of the tarsus forming the deep flexor tendon. This then branches and inserts on the distal phalanx of each digit.
* '''Medial digital flexor'''
** Origin - the head of the fibula and the popliteal line of the tibia.
** Insertion - It fuses with the medial digital flexor tendon forming the deep flexor tendon.
* '''Caudal tibial'''
** Origin - caudomedially surface of the tibia
** Insertion - the tendon radiates into the medial ligaments of the tarsus and doesn't form part of the deep flexor tendon.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Canine Paw==

Composed of four weight-bearing toes, each with a claw and footpad. In addition there is a metacarpal/metatarsal footpad.

====Footpad====
* The epidermis is thick, pigmented, keratinised and hairless. It is arranged into conical papillae. '''Sweat/merocrine glands''' open onto the surface.
* The dermis of the dense connective tissue is papillated.
* The subcutaneous tissue is mainly adipose tissue with reticular, collagenous and elastic fibres. These help form '''digital cushions''' deep to the foot pad.
* The '''digital pads''' are oval shaped and support the distal interphalangeal joints. The metacarpal/metatarsal pads are heart shaped, with the apex pointing distally and support the metacarpophalangeal joints.
* A small carpal pad is present medial and distal to the accessory carpal bone.

====Claw====

* This is the horny covering of the distal phalanx. The walls of the claw, which are continuous dorsally, embrace the soft flaky horn of the sole when they touch the ground.
* The proximal part of the claw, '''coronary border''' fits between the ungual groove and the ungual crest, where it is continuous with the skin, making the '''claw fold'''.
* The periosteum of the distal phalanx is continuous with the dermis, which is arranged in '''papillae'''. These cover the dorsal aspect of the phalanx and contain the '''germinative layer'''. These are flat keratinised epidermal cells which are considered responsible for horn formation.
* The lateral and medial walls are formed by dermal laminae, instead of papillae.
* The plantar aspect of the claw is produced by papillae but this horn is very friable.
* The claws grow at rapid rate and so if they aren't worn by active wear they must be trimmed. Care must be taken as the dermis is highly vascular and bleeding will occur if cut into. To ensure that only the epidermis is cut take great care.

Palpable Points of the Dog - Anatomy & Physiology

2008-09-11T15:11:38Z

Katherine: /* Crus and Tarsus */

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==Forelimb==

===Shoulder===

'''Skeleton'''
* Spine
* Scapula - spine, cranial angle, supraglenoid tubercle, acromion

'''Joint'''
* Flexion, extension, some abduction
* Joint cavity

'''Soft tissue'''
* Supraspinatus, infraspinatus, superficial and deep pectorals
* Biceps brachii tendon of origin
* Superficial cervical lymph node
* Brachial artery

===Brachium===

'''Skeleton'''
* Humeral shaft
* Greater and lesser tubercles
* Intertubercular groove
* Crest of the major tubercle
* Condyle and epicondyles

'''Soft tissue'''
* Biceps brachii
* Triceps brachii
* Brachialis
* Deltoid (acromial part)

===Elbow and Antebrachium===

'''Skeleton'''
* Radial head
* Olecranon
* Coronoid process
* Styloid process of radius and ulna

'''Joint'''
* Flexion and extension

'''Soft tissue'''
* Insertion of the triceps on the olecranon
* Extensor carpi radialis and common digital extensor
* Flexor carpi ulnaris and ulnaris lateralis
* Ligaments of the elbow
* Median artery pulse
* Cephalic vein venipuncture

===Carpus and Metacarpus===

'''Skeleton'''
* Accessory carpal bone and each metacarpal bone

'''Joint'''
* Flexion and extension

'''Soft tissue'''
* Termination of flexor carpi ulnaris and ulnaris lateralis on the accessory carpal bone
* Carpal canal
* Superficial digital flexor
* Carpal pad

===Metacarpophalangeal Joints and Phalanges===

* Each individual phalanx
* Flexion and extension of each MP and interphalangeal joint
* Flexor tendons crossing the palmar surface of the metacarpals and middle phalanx
* Claws of the digits
* Metacarpal pad and digital pads
* Digital artery

==Hindlimb==

===Pelvis and Hip===

'''Skeleton'''
* Tuber coxae and tuber sacrale
* Ischiatic tuberosity, arch and pubic tuberosity
* Greater trochanter of the femur
* Rectal examination is useful for diagnosing pelvic fractures

'''Joint'''
* Flexion and extension

'''Soft tissue'''
* Superficial and middle gluteal muscles
* Sacroiliac ligament

===Thigh and Stifle===

'''Skeleton'''
* Femoral shaft
* Greater trochanter
* Condyles
* Trochlear ridges
* Patella and fabellae

'''Joint'''
* Flexion, extension and mild rotation

'''Soft tissue'''
* Quadriceps femoris, Biceps femoris, Semitendinosus and Semimembranosus
* Patellar, collateral and cruciate ligaments
* Femoral artery
* Popliteal lymph node

===Crus and Tarsus===

'''Skeleton'''
* Tibial shaft, tibial tuberosity, cranial border and medial malleolus
* Fibular shaft, fibular head and lateral malleolus
* Trochlea of talus and tuber calcaneii

'''Joint'''
* Flexion and extension

'''Soft tissue'''
* Cranial tibialis, long digital extensor, gastrocnemius and superficial digital flexor
* Achilles tendon, collateral ligaments and plantar ligament
* Dorsal pedal artery, lateral cephalic vein and tarsal pad

===Metatarsus and Phalanges===
* As for forelimb

Arteries of the Hindlimb - Anatomy & Physiology

2008-09-08T17:03:06Z

Katherine: /* '''External Iliac Artery''' */

<big><center>[[Hindlimb - Anatomy & Physiology|'''BACK TO HINDLIMB''']]</center></big><big><center>[[Canine Hindlimb - Anatomy & Physiology|'''BACK TO CANINE HINDLIMB''']]</center></big>
<big><center>[[Equine Hindlimb - Anatomy & Physiology|'''BACK TO EQUINE HINDLIMB''']]</center></big>
<big><center>[[Bovine Hindlimb - Anatomy & Physiology|'''BACK TO BOVINE HINDLIMB''']]</center></big>
'''This page is based around the anatomy of the canine hindlimb.'''
'''Essentially the lay out of the arteries is similar in domestic species.'''
'''Any species differences will be discussed on their respective pages.'''

The '''abdominal aorta''' terminates by branching into the '''external iliac arteries''' and the '''internal iliac arteries'''. It is these arteries that supply the hindlimb and pelvis.

=='''The Internal Iliac Artery'''==

These are paired arteries, a right and a left branch, which is one of the terminal branches of the aorta. It provides a blood supply to the pelvic viscera, the walls of the pelvic cavity and the lumbar and gluteal muscle masses.

The initial branches in order of when they branch off are as follows (the highlighted vessels are ones that have direct relevance to the hindlimb);

* '''Median Sacral Artery''' - can arise from either left or right internal iliac and supplies the sacrum and tail.
* Internal Pudendal Artery - the primary branch of the internal iliac it provides blood to the reproductive organs and urinary tract
* '''Caudal Gluteal Artery''' - supplies the superficial gluteal muscle and the proximal 'hamstring muscles'.
** '''Iliolumbar Artery''' - the first branch of the caudal gluteal, it supplies the psoas minor, iliopsoas, sartorius, tensor fascia lata and the middle gluteal muscles.
** '''Cranial Gluteal Artery''' - arises from the caudal gluteal, it passes over the greater ischiatic notch and supplies the gluteal muscles.
** Lateral Caudal Artery - provides blood to the tail
* Dorsal Perineal Artery - supplies the perineum.

=='''External Iliac Artery'''==

The external iliac artery is the principal artery of the hindlimb. Once it branches from the aorta it runs along the ilial body. Prior to entering the '''femoral canal''' (formed by the sartorius cranially and the gracilis and pectineus caudally) it detaches the deep femoral artery and on leaving the abdomen the external iliac continues as the femoral artery. The femoral artery continues between the adductor muscles on the medial aspect of the thigh to reach the caudal side of the stifle. Here it continues as the popliteal artery.

Below are the arteries in the order in which they branch off the external iliac, femoral and popliteal arteries:

* '''External iliac a.'''
** '''Deep femoral a.''' - arises in the abdomen near the femoral canal and gives rise to the short pudendoepigastric trunk before continuing as the medial circumflex femoral artery.
*** '''The pudendoepigastric trunk'''
**** Caudal Epigastric a. - runs cranially on the deep aspect of the straight abdominal muscles.
**** External Pudendal a. - runs through the inguinal canal and branches off to supply numerous reproductive structures.
** '''Medial circumflex femoral a.''' - its supplies the caudal half of the rectus abdominus and the muscles of the medial thigh.

* '''Femoral a.'''
** '''Superficial circumflex iliac a.''' - it supplies the sartorius, tensor fascia lata and rectus femoris.
** '''Lateral circumflex femoral a.''' - branches off with the superficial circumflex; it supplies the quadriceps, tensor fascia lata, the superficial and middle gluteals, and the hip joint capsule.
** '''Proximal caudal femoral a.''' - branches off at the mid-thigh region and supplies the pectineus, adductor muscles and gracilis.
** '''Saphenous a.''' - arises proximal to the stifle and supplies the skin on the medial aspect of the stifle. It branches into a cranial and caudal branch. This artery and its vessels lie very superficially. The cranial branch gives rise to the '''dorsal common digital arteries''' and the caudal gives rise to the '''plantar common digital arteries'''; both of which supply the foot.
** '''Descending genincular a.''' - supplies the medial surface of the stifle.
** '''Middle caudal femoral a.''' - supplies the distal parts of the adductor and semimembranosus muscles.
** '''Distal caudal femoral a.''' - the last branch of the femoral artery before it becomes the politeal artery. It supplies the biceps femoris, semimembranosus, semitendinosus, gastrocnemius and the digital flexors.

* '''Popliteal a.''' - supplies the stifle, gastrocnemius, popliteal muscle and terminates by branching into the cranial and caudal tibial arteries.
** '''Cranial tibial a.''' - supplies the peroneus longus, long digital extensor and cranial tibial muscles.
*** '''Dorsal Pedal a.''' - a continuation of the cranial tibial artery, it runs over the flexor surface of the tarsus and supplies the tarsus.
**** '''Arcuate a.''' - the main blood supply to the foot.
***** '''Dorsal metatarsal aa.''' - supplies the paw dorsally.
****** '''Perforating branch''' - this anastomoses with the caudal branch of the saphenous artery and contribute to the plantar metatarsal arteries that supply the digits.
** '''Caudal tibial a.''' - a small branch that lies in the interosseous space between the tibia and fibula.

Arteries of the Hindlimb - Anatomy & Physiology

2008-09-08T16:45:46Z

Katherine: /* '''External Iliac Artery''' */

<big><center>[[Hindlimb - Anatomy & Physiology|'''BACK TO HINDLIMB''']]</center></big><big><center>[[Canine Hindlimb - Anatomy & Physiology|'''BACK TO CANINE HINDLIMB''']]</center></big>
<big><center>[[Equine Hindlimb - Anatomy & Physiology|'''BACK TO EQUINE HINDLIMB''']]</center></big>
<big><center>[[Bovine Hindlimb - Anatomy & Physiology|'''BACK TO BOVINE HINDLIMB''']]</center></big>
'''This page is based around the anatomy of the canine hindlimb.'''
'''Essentially the lay out of the arteries is similar in domestic species.'''
'''Any species differences will be discussed on their respective pages.'''

The '''abdominal aorta''' terminates by branching into the '''external iliac arteries''' and the '''internal iliac arteries'''. It is these arteries that supply the hindlimb and pelvis.

=='''The Internal Iliac Artery'''==

These are paired arteries, a right and a left branch, which is one of the terminal branches of the aorta. It provides a blood supply to the pelvic viscera, the walls of the pelvic cavity and the lumbar and gluteal muscle masses.

The initial branches in order of when they branch off are as follows (the highlighted vessels are ones that have direct relevance to the hindlimb);

* '''Median Sacral Artery''' - can arise from either left or right internal iliac and supplies the sacrum and tail.
* Internal Pudendal Artery - the primary branch of the internal iliac it provides blood to the reproductive organs and urinary tract
* '''Caudal Gluteal Artery''' - supplies the superficial gluteal muscle and the proximal 'hamstring muscles'.
** '''Iliolumbar Artery''' - the first branch of the caudal gluteal, it supplies the psoas minor, iliopsoas, sartorius, tensor fascia lata and the middle gluteal muscles.
** '''Cranial Gluteal Artery''' - arises from the caudal gluteal, it passes over the greater ischiatic notch and supplies the gluteal muscles.
** Lateral Caudal Artery - provides blood to the tail
* Dorsal Perineal Artery - supplies the perineum.

=='''External Iliac Artery'''==

The external iliac artery is the principal artery of the hindlimb. Once it branches from the aorta it runs along the ilial body. Prior to entering the '''femoral canal''' (formed by the sartorius cranially and the gracilis and pectineus caudally) it detaches the deep femoral artery and on leaving the abdomen the external iliac continues as the femoral artery. The femoral artery continues between the adductor muscles on the medial aspect of the thigh to reach the caudal side of the stifle. Here it continues as the popliteal artery.

Below are the arteries in the order in which they branch off the external iliac, femoral and popliteal arteries:

* '''External iliac a.'''
** '''Deep femoral a.''' - arises in the abdomen near the femoral canal and gives rise to the short pudendoepigastric trunk before continuing as the medial circumflex femoral artery.
*** '''The pudendoepigastric trunk'''
**** Caudal Epigastric a. - runs cranially on the deep aspect of the straight abdominal muscles.
**** External Pudendal a. - runs through the inguinal canal and branches off to supply numerous reproductive structures.
** '''Medial circumflex femoral a.''' - its supplies the caudal half of the rectus abdominus and the muscles of the medial thigh.

* '''Femoral a.'''
** '''Superficial circumflex iliac a.''' - it supplies the sartorius, tensor fascia lata and rectus femoris.
** '''Lateral circumflex femoral a.''' - branches off with the superficial circumflex; it supplies the quadriceps, tensor fascia lata, the superficial and middle gluteals, and the hip joint capsule.
** '''Proximal caudal femoral a.''' - branches off at the mid-thigh region and supplies the pectineus, adductor muscles and gracilis.
** '''Saphenous a.''' - arises proximal to the stifle and supplies the skin on the medial aspect of the stifle. It branches into a cranial and caudal branch. This artery and is vessels lie very superficially. The cranial branch gives rise to the '''dorsal common digital arteries''' and the caudal gives rise to the '''plantar common digital arteries'''; both of which supply the foot.
** '''Descending genincular a.''' - supplies the medial surface of the stifle.
** '''Middle caudal femoral a.''' - supplies the distal parts of the adductor and semimembranosus muscles.
** '''Distal caudal femoral a.''' - the last branch of the femoral artery before it becomes the politeal artery. It supplies the biceps femoris, semimembranosus, semitendinosus, gastrocnemius and the digital flexors.

* '''Popliteal a.''' - supplies the stifle, gastrocnemius, popliteal muscle and terminates by branching into the cranial and caudal tibial arteries.
** '''Cranial tibial a.''' - supplies the peroneus longus, long digital extensor and cranial tibial muscles.
*** '''Dorsal Pedal a.''' - a continuation of the cranial tibial artery, it runs over the flexor surface of the tarsus and supplies the tarsus.
**** '''Arcuate a.''' - the main blood supply to the foot.
***** '''Dorsal metatarsal aa.''' - supplies the paw dorsally.
****** '''Perforating branch''' - this anastomoses with the caudal branch of the saphenous artery and contribute to the plantar metatarsal arteries that supply the digits.
** '''Caudal tibial a.''' - a small branch that lies in the interosseous space between the tibia and fibula.

Arteries of the Hindlimb - Anatomy & Physiology

2008-09-08T16:42:06Z

Katherine: /* '''The Internal Iliac Artery''' */

<big><center>[[Hindlimb - Anatomy & Physiology|'''BACK TO HINDLIMB''']]</center></big><big><center>[[Canine Hindlimb - Anatomy & Physiology|'''BACK TO CANINE HINDLIMB''']]</center></big>
<big><center>[[Equine Hindlimb - Anatomy & Physiology|'''BACK TO EQUINE HINDLIMB''']]</center></big>
<big><center>[[Bovine Hindlimb - Anatomy & Physiology|'''BACK TO BOVINE HINDLIMB''']]</center></big>
'''This page is based around the anatomy of the canine hindlimb.'''
'''Essentially the lay out of the arteries is similar in domestic species.'''
'''Any species differences will be discussed on their respective pages.'''

The '''abdominal aorta''' terminates by branching into the '''external iliac arteries''' and the '''internal iliac arteries'''. It is these arteries that supply the hindlimb and pelvis.

=='''The Internal Iliac Artery'''==

These are paired arteries, a right and a left branch, which is one of the terminal branches of the aorta. It provides a blood supply to the pelvic viscera, the walls of the pelvic cavity and the lumbar and gluteal muscle masses.

The initial branches in order of when they branch off are as follows (the highlighted vessels are ones that have direct relevance to the hindlimb);

* '''Median Sacral Artery''' - can arise from either left or right internal iliac and supplies the sacrum and tail.
* Internal Pudendal Artery - the primary branch of the internal iliac it provides blood to the reproductive organs and urinary tract
* '''Caudal Gluteal Artery''' - supplies the superficial gluteal muscle and the proximal 'hamstring muscles'.
** '''Iliolumbar Artery''' - the first branch of the caudal gluteal, it supplies the psoas minor, iliopsoas, sartorius, tensor fascia lata and the middle gluteal muscles.
** '''Cranial Gluteal Artery''' - arises from the caudal gluteal, it passes over the greater ischiatic notch and supplies the gluteal muscles.
** Lateral Caudal Artery - provides blood to the tail
* Dorsal Perineal Artery - supplies the perineum.

=='''External Iliac Artery'''==

The external iliac artery is the principal artery of the hindlimb. Once it branches from the aorta it runs along the ilial body. Prior to entering the '''femoral canal''' (formed by the sartorius cranially and the gracilis and pectineus caudally) it detaches the deep femoral artery and on leaving the abdomen the external iliac continues as the femoral artery. The femoral artery continues between the adductor muscles on the medial aspect of the thigh to reach the caudal side of the stifle. Here it continues as the popliteal artery.

Below are the arteries in order in which they branch off the external iliac, femoral and popliteal arteries:

* '''External iliac a.'''
** '''Deep femoral a.''' - arises in the abdomen near the femoral canal and gives rise to the short pudendoepigastric trunk before continuing as the medial circumflex femoral artery.
*** '''The pudendoepigastric trunk'''
**** Caudal Epigastric a. - runs cranially on the deep aspect of the straight abdominal muscles.
**** External Pudendal a. - runs through the inguinal canal and branches off to supply numerous reproductive structures.
** '''Medial circumflex femoral a.''' - its supplies the caudal half of the rectus abdominus and the muscles of the medial thigh.

* '''Femoral a.'''
** '''Superficial circumflex iliac a.''' - it supplies the sartorius, tensor fascia lata and rectus femoris.
** '''Lateral circumflex femoral a.''' - branches off with the superficial circumflex; it supplies the quadriceps, tensor fascia lata, the superficial and middle gluteals, and the hip joint capsule.
** '''Proximal caudal femoral a.''' - branches off at the mid-thigh region and supplies the pectineus, adductor muscles and gracilis.
** '''Saphenous a.''' - arises proximal to the stifle and supplies the skin on the medial aspect of the stifle. It branches into a cranial and caudal branch. This artery and is vessels lie very superficially. The cranial branch gives rise to the '''dorsal common digital arteries''' and the caudal gives rise to the '''plantar common digital arteries'''; both of which supplie the foot.
** '''Descending genincular a.''' - supplies the medial surface of the stifle.
** '''Middle caudal femoral a.''' - supplies the distal parts of the adductor and semimembranosus muscles.
** '''Distal caudal femoral a.''' - the last branch of the femoral artery before it becomes the politeal artery. It supplies the biceps femoris, semimembranosus, semitendinosus, gastrocnemius and the digital flexors.

* '''Popliteal a.''' - supplies the stifle, gastrocnemius, popliteal muscle and terminates by branching into the cranial and caudal tibial arteries.
** '''Cranial tibial a.''' - supplies the peroneus longus, long digital extensor and cranial tibial muscles.
*** '''Dorsal Pedal a.''' - a continuation of the cranial tibial artery, it runs over the flexor surface of the tarsus and supplies the tarsus.
**** '''Arcuate a.''' - the main blood supply to the foot.
***** '''Dorsal metatarsal aa.''' - supplies the paw dorsally.
****** '''Perforating branch''' - this anastomoses with the caudal branch of the saphenous artery and contribute to the plantar metatarsal arteries that supply the digits.
** '''Caudal tibial a.''' - a small branch that lies in the interosseous space between the tibia and fibula.

Bovine Lower Limb - Anatomy & Physiology

2008-09-08T16:40:29Z

Katherine: /* The Bovine Claw */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
Cattle are '''artiodactyl unguligrade''' animals. Unguligrade means that they bear their weight on a horny covering (hoof) that surrounds their distal phalanges, artiodactyl means that they bear weight on an even number of digits. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* Metacarpal III and IV fuse in the fetus to form the large metacarpal bone. The site of fusion is marked by vascular grooves on the dorsal and palmar surfaces of the shaft of the bone. Metacarpal V remains only as a small lateral remnant.
* The distal end has two seperate articular surfaces seperated by the sagittal '''intertrochlear notch'''. The articular surfaces have two condyles seperated by a sagittal ridge.
* The dorsal aspect of the proximal end has a tuberosity for muscular attachment.

====Phalanges====

* The proximal phalanx tends to be triangular with the interdigital surface being flattened. The proximal end is concave with a sagittal groove so it can articulate with the metacarpal bone, the palmar aspect has facets for the sesamoid bones. The distal head has two convex areas seperated by a sagittal concavity.
* The middle phalanx is three sided and 2/3rds the length of the proximal one. The proximal end is made up of two concavities and a sagittal ridge. The distal end resembles that of the proximal phalanx.
* The distal phalanx is pointed, the proximal end has two articular surfaces seperated by a ridge. The solar surface is flattened and has a flexor tubercle for the attachment of the deep digital flexor tendon. The axial surface faicng the other digit is also flattened. The abaxial surface is rounded and is the parietal surface of the claw.
* Just distal to the metacarpophalangeal joint on the palmar aspect of the limb lie a pair of conical accessory claws. These are covered with horn and often contain dense connective tissue and small nodules of bone.

==Joints==

====Metacarpophalangeal/Fetlock Joint====

* Movement - flexion and extension.
* The cow has a pair of fetlock joints involving the metacarpal bone, the two proximal phalanges and two pairs of sesamoid bones. These sesamoids articulate with the proximal palmar edge of the proximal phalanges
* Cattle have a joint capsule for the articulation of each digit with the palmar parts communicating.
* '''Collateral ligaments''' - bind the the furrow between the two articulating areas of the metacarpal bone to the proximal phalanx.
* '''Interdigital intersesamoid ligament''' - unites the axial sesamoids of each digit together.
* '''Interdigital phalangosesamoid ligaments''' - a pair of ligaments that cross each other as they connect the sesamoid of one digit to the proximal phalanx of the other.
* '''Proximal interdigital ligament''' - connects the proximal halves of the two digits. Not technically part of the fetlock joint, it is absent in sheep.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the metacarpal bone.
* '''Distal sesamoid ligaments''' - a collection of ligaments that are very marked in the horse. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. These are:
** '''Short ligaments''' - connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments.
** '''Cruciate ligaments''' - paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments.

====Proximal Interphalangeal/Pastern Joint====

* Movement - flexion and extension.
* The joint capsule is simple and attaches by the articular margins of the two phalanges.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal/Coffin Joint====

* Movement - extension, slight flexion.
* A distal sesamoid is closely associated with the distal phalanx, which has a navicular bursa present like in the horse.
* The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the proximal distal phalanx.
* '''Dorsal ligament''' - yellow elastic tissue connecting the proximal dorsal border of the middle phalanx to the extensor process of the distal phalanx.
* '''Distal sesamoid ligaments'''' - connect the distal border of the distal sesamoid bone to the flexor surface of the distal phalanx and has axial and abaxial parts.
* '''Collateral sesamoid ligaments''' - fibroelastic ligaments that attach the middle phalanx to the proximal border of the navicular bone.
* '''Distal interdigital ligaments'''- cruciate ligaments that attach the abaxial aspect of the proximal end of the middle phalanx to the axial surface of the opposing distal phalanx and distal sesamoid.

==Musculature==

'''Interosseous/Suspensory ligament'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones, distal row of carpal bones and the joint capsule of the carpus.
* Insertion - At the distal third of the metacarpal bone it divides into three. The lateral branch further splits in two, attaches to the proximal sesamoids of the fetlock and then continues round dorsally on the proximal lateral phalanx and attaches to the lateral digital extensor tendon. The medial branch is likewise arranged but attaches to the medial digital extensor tendon. The middle branch dives between the groove of the distal part of the metacarpal bone and divides into two branches that attach to the tendons of the common digital extensor tendon.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - solar surface of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - solar surfaces of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus and the ulna.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - lateral epicondyle
* Insertion - by two branches to the middle and distal medial phalanges.

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral ligament of the elbow, lateral tuberosity of the radius, ulna.
* Insertion - by two branches to the middle and distal lateral phalanges.

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - the middle medial phalanx.

'''Lateral Digital Extensor'''
* Origin - lateral ligament of the stifle, lateral condyle of the tibia.
* Insertion - on the dorsal aspect of the middle lateral phalanx.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur.
* Insertion - solar surfaces of the middle phalanges.

'''Deep Digital Flexor'''
* Origin - lateral tibial condyle, fibula, interosseous ligament.
* Insertion - the solar surface of the distal phalanx.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Bovine Claw==

The claws of a cow resemble a disc split in half, hence the term cloven-hoof. The split is named the '''interdigital cleft''' and gives rise to the flattened '''axial surface''', the '''abaxial surface''' is the remaining rounded surface of the claw.
The claw is divided into three regions:

* '''Sole''' - slightly concave region on the point of the sole
* '''Bulb''' - slightly convex region at the heel of the sole
* '''Wall''' - on its abaxial aspect it is convex and merges with the bulb, dorsally it reflects acutely to the convex axial wall. The junction with the bulb has a groove called the '''axial cleft'''.

The dermis of the wall is very similar to the horse and is arranged in laminae. This interdigitates with the epidermal horn that is produced by the papillous coronary region. The horn on the sole and bulb is also produced by papillae. The hypodermis in the bulb forms a pad of fibrous elastic tissue called the '''digital cushion'''.

Bovine Lower Limb - Anatomy & Physiology

2008-09-08T16:38:04Z

Katherine: /* Musculature */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
Cattle are '''artiodactyl unguligrade''' animals. Unguligrade means that they bear their weight on a horny covering (hoof) that surrounds their distal phalanges, artiodactyl means that they bear weight on an even number of digits. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* Metacarpal III and IV fuse in the fetus to form the large metacarpal bone. The site of fusion is marked by vascular grooves on the dorsal and palmar surfaces of the shaft of the bone. Metacarpal V remains only as a small lateral remnant.
* The distal end has two seperate articular surfaces seperated by the sagittal '''intertrochlear notch'''. The articular surfaces have two condyles seperated by a sagittal ridge.
* The dorsal aspect of the proximal end has a tuberosity for muscular attachment.

====Phalanges====

* The proximal phalanx tends to be triangular with the interdigital surface being flattened. The proximal end is concave with a sagittal groove so it can articulate with the metacarpal bone, the palmar aspect has facets for the sesamoid bones. The distal head has two convex areas seperated by a sagittal concavity.
* The middle phalanx is three sided and 2/3rds the length of the proximal one. The proximal end is made up of two concavities and a sagittal ridge. The distal end resembles that of the proximal phalanx.
* The distal phalanx is pointed, the proximal end has two articular surfaces seperated by a ridge. The solar surface is flattened and has a flexor tubercle for the attachment of the deep digital flexor tendon. The axial surface faicng the other digit is also flattened. The abaxial surface is rounded and is the parietal surface of the claw.
* Just distal to the metacarpophalangeal joint on the palmar aspect of the limb lie a pair of conical accessory claws. These are covered with horn and often contain dense connective tissue and small nodules of bone.

==Joints==

====Metacarpophalangeal/Fetlock Joint====

* Movement - flexion and extension.
* The cow has a pair of fetlock joints involving the metacarpal bone, the two proximal phalanges and two pairs of sesamoid bones. These sesamoids articulate with the proximal palmar edge of the proximal phalanges
* Cattle have a joint capsule for the articulation of each digit with the palmar parts communicating.
* '''Collateral ligaments''' - bind the the furrow between the two articulating areas of the metacarpal bone to the proximal phalanx.
* '''Interdigital intersesamoid ligament''' - unites the axial sesamoids of each digit together.
* '''Interdigital phalangosesamoid ligaments''' - a pair of ligaments that cross each other as they connect the sesamoid of one digit to the proximal phalanx of the other.
* '''Proximal interdigital ligament''' - connects the proximal halves of the two digits. Not technically part of the fetlock joint, it is absent in sheep.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the metacarpal bone.
* '''Distal sesamoid ligaments''' - a collection of ligaments that are very marked in the horse. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. These are:
** '''Short ligaments''' - connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments.
** '''Cruciate ligaments''' - paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments.

====Proximal Interphalangeal/Pastern Joint====

* Movement - flexion and extension.
* The joint capsule is simple and attaches by the articular margins of the two phalanges.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal/Coffin Joint====

* Movement - extension, slight flexion.
* A distal sesamoid is closely associated with the distal phalanx, which has a navicular bursa present like in the horse.
* The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the proximal distal phalanx.
* '''Dorsal ligament''' - yellow elastic tissue connecting the proximal dorsal border of the middle phalanx to the extensor process of the distal phalanx.
* '''Distal sesamoid ligaments'''' - connect the distal border of the distal sesamoid bone to the flexor surface of the distal phalanx and has axial and abaxial parts.
* '''Collateral sesamoid ligaments''' - fibroelastic ligaments that attach the middle phalanx to the proximal border of the navicular bone.
* '''Distal interdigital ligaments'''- cruciate ligaments that attach the abaxial aspect of the proximal end of the middle phalanx to the axial surface of the opposing distal phalanx and distal sesamoid.

==Musculature==

'''Interosseous/Suspensory ligament'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones, distal row of carpal bones and the joint capsule of the carpus.
* Insertion - At the distal third of the metacarpal bone it divides into three. The lateral branch further splits in two, attaches to the proximal sesamoids of the fetlock and then continues round dorsally on the proximal lateral phalanx and attaches to the lateral digital extensor tendon. The medial branch is likewise arranged but attaches to the medial digital extensor tendon. The middle branch dives between the groove of the distal part of the metacarpal bone and divides into two branches that attach to the tendons of the common digital extensor tendon.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - solar surface of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - solar surfaces of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus and the ulna.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - lateral epicondyle
* Insertion - by two branches to the middle and distal medial phalanges.

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral ligament of the elbow, lateral tuberosity of the radius, ulna.
* Insertion - by two branches to the middle and distal lateral phalanges.

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - the middle medial phalanx.

'''Lateral Digital Extensor'''
* Origin - lateral ligament of the stifle, lateral condyle of the tibia.
* Insertion - on the dorsal aspect of the middle lateral phalanx.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur.
* Insertion - solar surfaces of the middle phalanges.

'''Deep Digital Flexor'''
* Origin - lateral tibial condyle, fibula, interosseous ligament.
* Insertion - the solar surface of the distal phalanx.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Bovine Claw==

The claws of a cow resemble a disc split in half, hence the term cloven-hoof. The split is named the '''interdigital cleft''' and gives rise to the flattened '''axial surface''', the '''abaxial surface''' is the remaining rounded surface of the claw.
The claw is divided into three regions:

* '''Sole''' - slightly concave region on the point of the sole
* '''Bulb''' - slightly convex region at the heel of the sole
* '''Wall''' - on its abaxial aspect it is convex and merges with the bulb, dorsally it reflects acutely to the convex axial wall. The junction with the bulb has a groove called the '''axial cleft'''.

The dermis of the wall is very similar to the horse and is arranged in laminae. This interdigitates with the epidermal horn that is produced by the papillous coronary region. The horn on the sole and bulb is also produced by papillae. The hpodermis in the bulb forms a pad of fibrous elastic tissue called the '''digital cushion'''.

Bovine Lower Limb - Anatomy & Physiology

2008-09-08T16:36:25Z

Katherine: /* Proximal Interphalangeal/Pastern Joint */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
Cattle are '''artiodactyl unguligrade''' animals. Unguligrade means that they bear their weight on a horny covering (hoof) that surrounds their distal phalanges, artiodactyl means that they bear weight on an even number of digits. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* Metacarpal III and IV fuse in the fetus to form the large metacarpal bone. The site of fusion is marked by vascular grooves on the dorsal and palmar surfaces of the shaft of the bone. Metacarpal V remains only as a small lateral remnant.
* The distal end has two seperate articular surfaces seperated by the sagittal '''intertrochlear notch'''. The articular surfaces have two condyles seperated by a sagittal ridge.
* The dorsal aspect of the proximal end has a tuberosity for muscular attachment.

====Phalanges====

* The proximal phalanx tends to be triangular with the interdigital surface being flattened. The proximal end is concave with a sagittal groove so it can articulate with the metacarpal bone, the palmar aspect has facets for the sesamoid bones. The distal head has two convex areas seperated by a sagittal concavity.
* The middle phalanx is three sided and 2/3rds the length of the proximal one. The proximal end is made up of two concavities and a sagittal ridge. The distal end resembles that of the proximal phalanx.
* The distal phalanx is pointed, the proximal end has two articular surfaces seperated by a ridge. The solar surface is flattened and has a flexor tubercle for the attachment of the deep digital flexor tendon. The axial surface faicng the other digit is also flattened. The abaxial surface is rounded and is the parietal surface of the claw.
* Just distal to the metacarpophalangeal joint on the palmar aspect of the limb lie a pair of conical accessory claws. These are covered with horn and often contain dense connective tissue and small nodules of bone.

==Joints==

====Metacarpophalangeal/Fetlock Joint====

* Movement - flexion and extension.
* The cow has a pair of fetlock joints involving the metacarpal bone, the two proximal phalanges and two pairs of sesamoid bones. These sesamoids articulate with the proximal palmar edge of the proximal phalanges
* Cattle have a joint capsule for the articulation of each digit with the palmar parts communicating.
* '''Collateral ligaments''' - bind the the furrow between the two articulating areas of the metacarpal bone to the proximal phalanx.
* '''Interdigital intersesamoid ligament''' - unites the axial sesamoids of each digit together.
* '''Interdigital phalangosesamoid ligaments''' - a pair of ligaments that cross each other as they connect the sesamoid of one digit to the proximal phalanx of the other.
* '''Proximal interdigital ligament''' - connects the proximal halves of the two digits. Not technically part of the fetlock joint, it is absent in sheep.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the metacarpal bone.
* '''Distal sesamoid ligaments''' - a collection of ligaments that are very marked in the horse. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. These are:
** '''Short ligaments''' - connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments.
** '''Cruciate ligaments''' - paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments.

====Proximal Interphalangeal/Pastern Joint====

* Movement - flexion and extension.
* The joint capsule is simple and attaches by the articular margins of the two phalanges.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal/Coffin Joint====

* Movement - extension, slight flexion.
* A distal sesamoid is closely associated with the distal phalanx, which has a navicular bursa present like in the horse.
* The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the proximal distal phalanx.
* '''Dorsal ligament''' - yellow elastic tissue connecting the proximal dorsal border of the middle phalanx to the extensor process of the distal phalanx.
* '''Distal sesamoid ligaments'''' - connect the distal border of the distal sesamoid bone to the flexor surface of the distal phalanx and has axial and abaxial parts.
* '''Collateral sesamoid ligaments''' - fibroelastic ligaments that attach the middle phalanx to the proximal border of the navicular bone.
* '''Distal interdigital ligaments'''- cruciate ligaments that attach the abaxial aspect of the proximal end of the middle phalanx to the axial surface of the opposing distal phalanx and distal sesamoid.

==Musculature==

'''Interosseous/Suspensory ligament'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones, distal row of carpal bones and the joint capsule of the carpus.
* Insertion - At the distal third of the metacarpal bone it divides into three. The lateral branch further splits in two, attaches to the proximal sesamoids of the fetlock and then continue round dorsally on the proximal lateral phalanx and attach to the lateral digital extensor tendon. The medial branch is likewise arranged but attaches to the medial digital extensor tendon. The middle branch dives between the groove of the distal part of the metacarpal bone and divides into two branches that attach to the tendons of the common digital extensor tendon.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - solar surface of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - solar surfaces of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus and the ulna.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - lateral epicondyle
* Insertion - by two branches to the middle and distal medial phalanges.

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral ligament of the elbow, lateral tuberosity of the radius, ulna.
* Insertion - by two branches to the middle and distal lateral phalanges.

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - the middle medial phalanx.

'''Lateral Digital Extensor'''
* Origin - lateral ligament of the stifle, lateral condyle of the tibia.
* Insertion - on the dorsal aspect of the middle lateral phalanx.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur.
* Insertion - solar surfaces of the middle phalanges.

'''Deep Digital Flexor'''
* Origin - lateral tibial condyle, fibula, interosseous ligament.
* Insertion - the solar surface of the distal phalanx.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Bovine Claw==

The claws of a cow resemble a disc split in half, hence the term cloven-hoof. The split is named the '''interdigital cleft''' and gives rise to the flattened '''axial surface''', the '''abaxial surface''' is the remaining rounded surface of the claw.
The claw is divided into three regions:

* '''Sole''' - slightly concave region on the point of the sole
* '''Bulb''' - slightly convex region at the heel of the sole
* '''Wall''' - on its abaxial aspect it is convex and merges with the bulb, dorsally it reflects acutely to the convex axial wall. The junction with the bulb has a groove called the '''axial cleft'''.

The dermis of the wall is very similar to the horse and is arranged in laminae. This interdigitates with the epidermal horn that is produced by the papillous coronary region. The horn on the sole and bulb is also produced by papillae. The hpodermis in the bulb forms a pad of fibrous elastic tissue called the '''digital cushion'''.

Bovine Lower Limb - Anatomy & Physiology

2008-09-08T16:35:53Z

Katherine: /* Metacarpophalangeal/Fetlock Joint */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
Cattle are '''artiodactyl unguligrade''' animals. Unguligrade means that they bear their weight on a horny covering (hoof) that surrounds their distal phalanges, artiodactyl means that they bear weight on an even number of digits. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* Metacarpal III and IV fuse in the fetus to form the large metacarpal bone. The site of fusion is marked by vascular grooves on the dorsal and palmar surfaces of the shaft of the bone. Metacarpal V remains only as a small lateral remnant.
* The distal end has two seperate articular surfaces seperated by the sagittal '''intertrochlear notch'''. The articular surfaces have two condyles seperated by a sagittal ridge.
* The dorsal aspect of the proximal end has a tuberosity for muscular attachment.

====Phalanges====

* The proximal phalanx tends to be triangular with the interdigital surface being flattened. The proximal end is concave with a sagittal groove so it can articulate with the metacarpal bone, the palmar aspect has facets for the sesamoid bones. The distal head has two convex areas seperated by a sagittal concavity.
* The middle phalanx is three sided and 2/3rds the length of the proximal one. The proximal end is made up of two concavities and a sagittal ridge. The distal end resembles that of the proximal phalanx.
* The distal phalanx is pointed, the proximal end has two articular surfaces seperated by a ridge. The solar surface is flattened and has a flexor tubercle for the attachment of the deep digital flexor tendon. The axial surface faicng the other digit is also flattened. The abaxial surface is rounded and is the parietal surface of the claw.
* Just distal to the metacarpophalangeal joint on the palmar aspect of the limb lie a pair of conical accessory claws. These are covered with horn and often contain dense connective tissue and small nodules of bone.

==Joints==

====Metacarpophalangeal/Fetlock Joint====

* Movement - flexion and extension.
* The cow has a pair of fetlock joints involving the metacarpal bone, the two proximal phalanges and two pairs of sesamoid bones. These sesamoids articulate with the proximal palmar edge of the proximal phalanges
* Cattle have a joint capsule for the articulation of each digit with the palmar parts communicating.
* '''Collateral ligaments''' - bind the the furrow between the two articulating areas of the metacarpal bone to the proximal phalanx.
* '''Interdigital intersesamoid ligament''' - unites the axial sesamoids of each digit together.
* '''Interdigital phalangosesamoid ligaments''' - a pair of ligaments that cross each other as they connect the sesamoid of one digit to the proximal phalanx of the other.
* '''Proximal interdigital ligament''' - connects the proximal halves of the two digits. Not technically part of the fetlock joint, it is absent in sheep.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the metacarpal bone.
* '''Distal sesamoid ligaments''' - a collection of ligaments that are very marked in the horse. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. These are:
** '''Short ligaments''' - connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments.
** '''Cruciate ligaments''' - paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments.

====Proximal Interphalangeal/Pastern Joint====

* Movement - flexion and extension.
* The joint capsule is simple and attaches by thr articular margins of the two phalanges.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal/Coffin Joint====

* Movement - extension, slight flexion.
* A distal sesamoid is closely associated with the distal phalanx, which has a navicular bursa present like in the horse.
* The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the proximal distal phalanx.
* '''Dorsal ligament''' - yellow elastic tissue connecting the proximal dorsal border of the middle phalanx to the extensor process of the distal phalanx.
* '''Distal sesamoid ligaments'''' - connect the distal border of the distal sesamoid bone to the flexor surface of the distal phalanx and has axial and abaxial parts.
* '''Collateral sesamoid ligaments''' - fibroelastic ligaments that attach the middle phalanx to the proximal border of the navicular bone.
* '''Distal interdigital ligaments'''- cruciate ligaments that attach the abaxial aspect of the proximal end of the middle phalanx to the axial surface of the opposing distal phalanx and distal sesamoid.

==Musculature==

'''Interosseous/Suspensory ligament'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones, distal row of carpal bones and the joint capsule of the carpus.
* Insertion - At the distal third of the metacarpal bone it divides into three. The lateral branch further splits in two, attaches to the proximal sesamoids of the fetlock and then continue round dorsally on the proximal lateral phalanx and attach to the lateral digital extensor tendon. The medial branch is likewise arranged but attaches to the medial digital extensor tendon. The middle branch dives between the groove of the distal part of the metacarpal bone and divides into two branches that attach to the tendons of the common digital extensor tendon.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - solar surface of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - solar surfaces of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus and the ulna.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - lateral epicondyle
* Insertion - by two branches to the middle and distal medial phalanges.

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral ligament of the elbow, lateral tuberosity of the radius, ulna.
* Insertion - by two branches to the middle and distal lateral phalanges.

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - the middle medial phalanx.

'''Lateral Digital Extensor'''
* Origin - lateral ligament of the stifle, lateral condyle of the tibia.
* Insertion - on the dorsal aspect of the middle lateral phalanx.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur.
* Insertion - solar surfaces of the middle phalanges.

'''Deep Digital Flexor'''
* Origin - lateral tibial condyle, fibula, interosseous ligament.
* Insertion - the solar surface of the distal phalanx.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Bovine Claw==

The claws of a cow resemble a disc split in half, hence the term cloven-hoof. The split is named the '''interdigital cleft''' and gives rise to the flattened '''axial surface''', the '''abaxial surface''' is the remaining rounded surface of the claw.
The claw is divided into three regions:

* '''Sole''' - slightly concave region on the point of the sole
* '''Bulb''' - slightly convex region at the heel of the sole
* '''Wall''' - on its abaxial aspect it is convex and merges with the bulb, dorsally it reflects acutely to the convex axial wall. The junction with the bulb has a groove called the '''axial cleft'''.

The dermis of the wall is very similar to the horse and is arranged in laminae. This interdigitates with the epidermal horn that is produced by the papillous coronary region. The horn on the sole and bulb is also produced by papillae. The hpodermis in the bulb forms a pad of fibrous elastic tissue called the '''digital cushion'''.

Bovine Lower Limb - Anatomy & Physiology

2008-09-08T16:33:57Z

Katherine: /* Phalanges */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
Cattle are '''artiodactyl unguligrade''' animals. Unguligrade means that they bear their weight on a horny covering (hoof) that surrounds their distal phalanges, artiodactyl means that they bear weight on an even number of digits. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* Metacarpal III and IV fuse in the fetus to form the large metacarpal bone. The site of fusion is marked by vascular grooves on the dorsal and palmar surfaces of the shaft of the bone. Metacarpal V remains only as a small lateral remnant.
* The distal end has two seperate articular surfaces seperated by the sagittal '''intertrochlear notch'''. The articular surfaces have two condyles seperated by a sagittal ridge.
* The dorsal aspect of the proximal end has a tuberosity for muscular attachment.

====Phalanges====

* The proximal phalanx tends to be triangular with the interdigital surface being flattened. The proximal end is concave with a sagittal groove so it can articulate with the metacarpal bone, the palmar aspect has facets for the sesamoid bones. The distal head has two convex areas seperated by a sagittal concavity.
* The middle phalanx is three sided and 2/3rds the length of the proximal one. The proximal end is made up of two concavities and a sagittal ridge. The distal end resembles that of the proximal phalanx.
* The distal phalanx is pointed, the proximal end has two articular surfaces seperated by a ridge. The solar surface is flattened and has a flexor tubercle for the attachment of the deep digital flexor tendon. The axial surface faicng the other digit is also flattened. The abaxial surface is rounded and is the parietal surface of the claw.
* Just distal to the metacarpophalangeal joint on the palmar aspect of the limb lie a pair of conical accessory claws. These are covered with horn and often contain dense connective tissue and small nodules of bone.

==Joints==

====Metacarpophalangeal/Fetlock Joint====

* Movement - flexion and extension.
* The cow has a pair of fetlock joints involving the metacarpal bone, the two proximal phalanges and two pairs of sesamoid bones. These sesamoids articulate with the proximal palmar edge of the proximal phalanges
* Cattle have a joint capsule for the articulation of each digit with the palmar parts communicating.
* '''Collateral ligaments''' - bind the the furrow between the two articulating areas of the metacarpal bone to the proximal phalanx.
* '''Interdigital intersesamoid ligament''' - units the axial sesamoids of each digit together.
* '''Interdigital phalangosesamoid ligaments''' - a pair of ligaments that cross each other as they connect thesesamoid of one digit to the proximal phalanx of the other.
* '''Proximal interdigital ligament''' - connects the proximal halves of the two digits. Not technically part of the fetlock joint, it is absent in sheep.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx and there is a distinct branch that attaches to the metacarpal bone.
* '''Distal sesamoid ligaments''' - a collection of ligaments that are very marked in the horse. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. These are:
** '''Short ligaments''' - connect the axial base of the sesamoids to the lateral/medial aspect on the palmar margin of the proximal phalanx. These are the deepest of the ligaments.
** '''Cruciate ligaments''' - paired ligaments from the base of the sesamoids that diagonally cross to attach to the proximal phalanx. It lies superficial to the short ligaments.

====Proximal Interphalangeal/Pastern Joint====

* Movement - flexion and extension.
* The joint capsule is simple and attaches by thr articular margins of the two phalanges.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal/Coffin Joint====

* Movement - extension, slight flexion.
* A distal sesamoid is closely associated with the distal phalanx, which has a navicular bursa present like in the horse.
* The joint capsule attaches to the articular periphery. There is a dorsal recess under the extensor tendons and a palmar one that runs to about half the height of the middle phalanx.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the proximal distal phalanx.
* '''Dorsal ligament''' - yellow elastic tissue connecting the proximal dorsal border of the middle phalanx to the extensor process of the distal phalanx.
* '''Distal sesamoid ligaments'''' - connect the distal border of the distal sesamoid bone to the flexor surface of the distal phalanx and has axial and abaxial parts.
* '''Collateral sesamoid ligaments''' - fibroelastic ligaments that attach the middle phalanx to the proximal border of the navicular bone.
* '''Distal interdigital ligaments'''- cruciate ligaments that attach the abaxial aspect of the proximal end of the middle phalanx to the axial surface of the opposing distal phalanx and distal sesamoid.

==Musculature==

'''Interosseous/Suspensory ligament'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones, distal row of carpal bones and the joint capsule of the carpus.
* Insertion - At the distal third of the metacarpal bone it divides into three. The lateral branch further splits in two, attaches to the proximal sesamoids of the fetlock and then continue round dorsally on the proximal lateral phalanx and attach to the lateral digital extensor tendon. The medial branch is likewise arranged but attaches to the medial digital extensor tendon. The middle branch dives between the groove of the distal part of the metacarpal bone and divides into two branches that attach to the tendons of the common digital extensor tendon.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - solar surface of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - solar surfaces of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus and the ulna.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - lateral epicondyle
* Insertion - by two branches to the middle and distal medial phalanges.

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral ligament of the elbow, lateral tuberosity of the radius, ulna.
* Insertion - by two branches to the middle and distal lateral phalanges.

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - It splits in two at the level of the fetlock, each branch then inserting on the extensor process of each distal phalanx.

'''Medial digital extensor'''
* Function - extensor of the medial digit
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - the middle medial phalanx.

'''Lateral Digital Extensor'''
* Origin - lateral ligament of the stifle, lateral condyle of the tibia.
* Insertion - on the dorsal aspect of the middle lateral phalanx.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur.
* Insertion - solar surfaces of the middle phalanges.

'''Deep Digital Flexor'''
* Origin - lateral tibial condyle, fibula, interosseous ligament.
* Insertion - the solar surface of the distal phalanx.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Bovine Claw==

The claws of a cow resemble a disc split in half, hence the term cloven-hoof. The split is named the '''interdigital cleft''' and gives rise to the flattened '''axial surface''', the '''abaxial surface''' is the remaining rounded surface of the claw.
The claw is divided into three regions:

* '''Sole''' - slightly concave region on the point of the sole
* '''Bulb''' - slightly convex region at the heel of the sole
* '''Wall''' - on its abaxial aspect it is convex and merges with the bulb, dorsally it reflects acutely to the convex axial wall. The junction with the bulb has a groove called the '''axial cleft'''.

The dermis of the wall is very similar to the horse and is arranged in laminae. This interdigitates with the epidermal horn that is produced by the papillous coronary region. The horn on the sole and bulb is also produced by papillae. The hpodermis in the bulb forms a pad of fibrous elastic tissue called the '''digital cushion'''.

Canine Phalanges - Anatomy & Physiology

2008-09-08T16:14:11Z

Katherine: /* Footpad */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

Dogs are '''digitigrade''' animals; this means that the weightbearing surface of their limbs is their digit. The canine phalanges are thus very important. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* They are rod shaped bones, numbered from I to V. The 1st is the most medial and is very small, the 3rd and 4th are the longest.
* The proximal base articulates with it's corresponding carpal bone and the adjacent metacarpal.
* The distal end is it's head, which is transversely cylindrical and articulates with the proximal phalanx.
* Metacarpals II - V possess a sagittal ridge on their palmar aspects.

====Phalanges====

* Proximal phalanx - of the main digits (II - V) they have a concave articular surface proximally. The palmar border has a groove to accomodate the articular surface of the metacarpus when the joint is fixed. The distal head has two convex areas seperated by a groove.
* Middle phalanx - roughly two-thirds the length of the proximal, its base has a sagittal ridge on the articular surface, which articulates with the groove of the proximal phalanx. The head resembles that of the proximal.
* Distal phalanx - made up of a cone-shaped ungual process with a distinct collar, '''ungual crest'''. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw. It articulates with the middle phalanx via a small sagittal crest.
* A bony sesamoid bone is found on the dorsal aspect of the metacarpophalangeal joint.
* The 'dew claw', metacarpal I, is normally present in the forelimb but often not in the hindlimb. It normally only consists two phalanges that resemble the proximal and distal ones.

==Joints==

====Metacarpophalangeal Joint====

* Movement - flexion and extension.
* Each joint, bar the first digit, has a pair of sesamoid bones associated with the palmar aspect of the joint. They articulate with a concave area of the proximal phalanx.
* The joint capsule runs between the four bones of the joint. Dorsally it extends under the extensor tendon, this part also intermingles with with an expanding area of the common digital extensor tendon. Distally it binds to the articular cartilage of the proximal phalanx and on the palmar aspect its dorsal attachment is level with the proximal end of the sesamoid bones.
* '''Collateral ligaments''' - bind the the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone.
* '''Palmar/intersesamoidean ligament''' - a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx.
* '''Distal sesamoid ligaments''' - a collection of ligaments that aren't well developed in the dog. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. They include the cruciate and short ligaments.
* The '''superficial transverse metacarpal ligaments''' surround the flexor tendons and their sheaths at the point of the sesamoid ligaments.
* The '''distal annular ligaments''' cross the surface of the flexor tendons and sheaths at the level of the proximal and middle phalanx.

====Proximal Interphalangeal Joint====

* Movement - flexion and extension.
* The joint capsule attaches near the articular surfaces of the proximal and middle phalanges. It extends slightly in a pouch dorsally and more extensively on the palmar aspect. The dorsal capsule is reinforced by a fibrocartilaginous nodule; the extensor tendon attaches to the capsule here.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal Joint====

* Movement - extension, slight flexion.
* The joint capsule attaches to the articular periphery of the bones and has a small fibrocartilagenous bead in the palmar aspect.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the ungual crest of the distal phalanx.
* '''Dorsal ligament''' - connects the proximal dorsal border of the extensor process of the distal phalanx. These are paired in dogs and function is to keep the claw raised until contraction of the deep digital flexor acts to overcome their tension.

==Musculature==

'''Interosseous'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones.
* Insertion - sesamoid bones of the metacarpophalangeal joint, it then continues as extensor branches that wrap round the dorsal aspect of the digit to join the extensor tendons.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - palmar aspect of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - palmar aspect of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - extensor process, distal phalanx

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - proximal phalanx

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - flexor aspect of the tarsus and branches which continue onto the extensor process of each of the distal phalanges.
* It divides into four branches at the level of the tarsus and are bound by the fibrous transverse bands of the proximal and distal retinaculum and are enclosed by a common synovial sheath.

'''Lateral Digital Extensor'''
* Origin - proximal fibula and lateral collateral ligament of the stifle.
* Insertion - It joins to the tendon of the long digital extensor to insert on the distal phalanx of the 5th digit.

'''Long Extensor of the first digit'''
* Origin - Proximal fibula
* Insertion - the metatarsophalangeal joint of the 2nd and 1st digit.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur and is firmly united to the lateral head of the gastrocnemius.
* Insertion - Middle phalanx of the 2nd to 5th digits.
* The muscle belly converges into a strong tendon at mid-tibial level and runs medially to the gastrocnemius to the point of the hock forming a broad cap. This cap is held in place by medial and lateral retinaculae.
* A '''synovial bursa''' lies between this cap and the calcaneal tuberosity.
* It then runs over the plantar aspect of the hock and splits twice at the level of the dorsal tarsal bones, thus forming it's four branches for insertion.

'''Deep Digital Flexor'''
* This muscle consists of three seperate heads; the '''caudal tibial muscle''', the '''lateral digital flexor muscle''' and the '''medial digital flexor muscle'''.
* '''Lateral digital flexor'''
** Origin - caudal surface of the tibia and fibula
** Insertion - its strong tendon fuses with that of the medial digital flexor tendon on the plantar aspect of the tarsus forming the deep flexor tendon. This then branches and inserts on the distal phalanx of each digit.
* '''Medial digital flexor'''
** Origin - the head of the fibula and the popliteal line of the tibia.
** Insertion - It fuses with the medial digital flexor tendon forming the deep flexor tendon.
* '''Caudal tibial'''
** Origin - caudomedially surface of the tibia
** Insertion - the tendon radiates into the medial ligaments of the tarsus and doesn't form part of the deep flexor tendon.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Canine Paw==

Composed of four weight-bearing toes, each with a claw and footpad. In addition there is a metacarpal/metatarsal footpad.

====Footpad====
* The epidermis is thick, pigmented, keratinised and hairless. It is arranged into conical papillae. '''Sweat/merocrine glands''' open onto the surface.
* The dermis of the dense connective tissue is papillated.
* The subcutaneous tissue is mainly adipose tissue with reticular, collagenous and elastic fibres. These help form '''digital cushions''' deep to the foot pad.
* The '''digital pads''' are oval shaped and support the distal interphalangeal joints. The metacarpal/metatarsal pads are heart shaped, with the apex pointing distally and support the metacarpophalangeal joints.
* A small carpal pad is present medial and distal to the accessory carpal bone.

====Claw====

* This is the horny covering of the distal phalanx. The walls of the claw, which are continuous dorsally, embrace the soft flaky horn of the sole when they touch the ground.
* The proximal part of the claw, '''coronary border''' fits between the ungual groove and the ungual crest, where it is continuous with the skin, making the '''claw fold'''.
* The periosteum of the distal phalanx is continuous with the dermis, which is arranged in '''papillae'''. These cover the dorsal aspect of the phalanx and contain the '''germinative layer'''. These are flat keratinised epidermal cells which are considered responsible for horn formation.
* The lateral and medial walls are formed by dermal laminae, instead of papillae.
* The plantar aspect of the claw is produced by papillae but this horn is very friable.
* The claws grow at rapid rate and so if they aren't worn by active wear they must be trimmed. Care must be taken as the dermis is highly vascular and bleeding will occur if cut into. To ensure that only the epidermis is cut take great care.

Canine Phalanges - Anatomy & Physiology

2008-09-08T16:13:03Z

Katherine: /* Hindlimb */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

Dogs are '''digitigrade''' animals; this means that the weightbearing surface of their limbs is their digit. The canine phalanges are thus very important. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* They are rod shaped bones, numbered from I to V. The 1st is the most medial and is very small, the 3rd and 4th are the longest.
* The proximal base articulates with it's corresponding carpal bone and the adjacent metacarpal.
* The distal end is it's head, which is transversely cylindrical and articulates with the proximal phalanx.
* Metacarpals II - V possess a sagittal ridge on their palmar aspects.

====Phalanges====

* Proximal phalanx - of the main digits (II - V) they have a concave articular surface proximally. The palmar border has a groove to accomodate the articular surface of the metacarpus when the joint is fixed. The distal head has two convex areas seperated by a groove.
* Middle phalanx - roughly two-thirds the length of the proximal, its base has a sagittal ridge on the articular surface, which articulates with the groove of the proximal phalanx. The head resembles that of the proximal.
* Distal phalanx - made up of a cone-shaped ungual process with a distinct collar, '''ungual crest'''. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw. It articulates with the middle phalanx via a small sagittal crest.
* A bony sesamoid bone is found on the dorsal aspect of the metacarpophalangeal joint.
* The 'dew claw', metacarpal I, is normally present in the forelimb but often not in the hindlimb. It normally only consists two phalanges that resemble the proximal and distal ones.

==Joints==

====Metacarpophalangeal Joint====

* Movement - flexion and extension.
* Each joint, bar the first digit, has a pair of sesamoid bones associated with the palmar aspect of the joint. They articulate with a concave area of the proximal phalanx.
* The joint capsule runs between the four bones of the joint. Dorsally it extends under the extensor tendon, this part also intermingles with with an expanding area of the common digital extensor tendon. Distally it binds to the articular cartilage of the proximal phalanx and on the palmar aspect its dorsal attachment is level with the proximal end of the sesamoid bones.
* '''Collateral ligaments''' - bind the the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone.
* '''Palmar/intersesamoidean ligament''' - a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx.
* '''Distal sesamoid ligaments''' - a collection of ligaments that aren't well developed in the dog. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. They include the cruciate and short ligaments.
* The '''superficial transverse metacarpal ligaments''' surround the flexor tendons and their sheaths at the point of the sesamoid ligaments.
* The '''distal annular ligaments''' cross the surface of the flexor tendons and sheaths at the level of the proximal and middle phalanx.

====Proximal Interphalangeal Joint====

* Movement - flexion and extension.
* The joint capsule attaches near the articular surfaces of the proximal and middle phalanges. It extends slightly in a pouch dorsally and more extensively on the palmar aspect. The dorsal capsule is reinforced by a fibrocartilaginous nodule; the extensor tendon attaches to the capsule here.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal Joint====

* Movement - extension, slight flexion.
* The joint capsule attaches to the articular periphery of the bones and has a small fibrocartilagenous bead in the palmar aspect.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the ungual crest of the distal phalanx.
* '''Dorsal ligament''' - connects the proximal dorsal border of the extensor process of the distal phalanx. These are paired in dogs and function is to keep the claw raised until contraction of the deep digital flexor acts to overcome their tension.

==Musculature==

'''Interosseous'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones.
* Insertion - sesamoid bones of the metacarpophalangeal joint, it then continues as extensor branches that wrap round the dorsal aspect of the digit to join the extensor tendons.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - palmar aspect of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - palmar aspect of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - extensor process, distal phalanx

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - proximal phalanx

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - flexor aspect of the tarsus and branches which continue onto the extensor process of each of the distal phalanges.
* It divides into four branches at the level of the tarsus and are bound by the fibrous transverse bands of the proximal and distal retinaculum and are enclosed by a common synovial sheath.

'''Lateral Digital Extensor'''
* Origin - proximal fibula and lateral collateral ligament of the stifle.
* Insertion - It joins to the tendon of the long digital extensor to insert on the distal phalanx of the 5th digit.

'''Long Extensor of the first digit'''
* Origin - Proximal fibula
* Insertion - the metatarsophalangeal joint of the 2nd and 1st digit.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur and is firmly united to the lateral head of the gastrocnemius.
* Insertion - Middle phalanx of the 2nd to 5th digits.
* The muscle belly converges into a strong tendon at mid-tibial level and runs medially to the gastrocnemius to the point of the hock forming a broad cap. This cap is held in place by medial and lateral retinaculae.
* A '''synovial bursa''' lies between this cap and the calcaneal tuberosity.
* It then runs over the plantar aspect of the hock and splits twice at the level of the dorsal tarsal bones, thus forming it's four branches for insertion.

'''Deep Digital Flexor'''
* This muscle consists of three seperate heads; the '''caudal tibial muscle''', the '''lateral digital flexor muscle''' and the '''medial digital flexor muscle'''.
* '''Lateral digital flexor'''
** Origin - caudal surface of the tibia and fibula
** Insertion - its strong tendon fuses with that of the medial digital flexor tendon on the plantar aspect of the tarsus forming the deep flexor tendon. This then branches and inserts on the distal phalanx of each digit.
* '''Medial digital flexor'''
** Origin - the head of the fibula and the popliteal line of the tibia.
** Insertion - It fuses with the medial digital flexor tendon forming the deep flexor tendon.
* '''Caudal tibial'''
** Origin - caudomedially surface of the tibia
** Insertion - the tendon radiates into the medial ligaments of the tarsus and doesn't form part of the deep flexor tendon.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Canine Paw==

Composed of four weight-bearing toes, each with a claw and footpad. In addition there is a metacarpal/metatarsal footpad.

====Footpad====
* The epidermis is thick, pigmented, keratinised and hairless. It is arranged into conical papillae. '''Sweat/merocrine glands''' open onto the surface.
* The dermis of the dense connective tissue is papillated.
* The subcutaneous tissue is mainly asipose tissue with reticular, collagenous and elastic fibres. These help form '''digital cushions''' deep to the foot pad.
* The '''digital pads''' are oval shaped and support the distal interphalangeal joints. The metacarpal/metatarsal pads are heart shaped, with the apex pointing distally and support the metacarpophalangeal joints.
* A small carpal pad is present medial and distal to the accessory carpal bone.

====Claw====

* This is the horny covering of the distal phalanx. The walls of the claw, which are continuous dorsally, embrace the soft flaky horn of the sole when they touch the ground.
* The proximal part of the claw, '''coronary border''' fits between the ungual groove and the ungual crest, where it is continuous with the skin, making the '''claw fold'''.
* The periosteum of the distal phalanx is continuous with the dermis, which is arranged in '''papillae'''. These cover the dorsal aspect of the phalanx and contain the '''germinative layer'''. These are flat keratinised epidermal cells which are considered responsible for horn formation.
* The lateral and medial walls are formed by dermal laminae, instead of papillae.
* The plantar aspect of the claw is produced by papillae but this horn is very friable.
* The claws grow at rapid rate and so if they aren't worn by active wear they must be trimmed. Care must be taken as the dermis is highly vascular and bleeding will occur if cut into. To ensure that only the epidermis is cut take great care.

Canine Phalanges - Anatomy & Physiology

2008-09-08T16:07:17Z

Katherine: /* Metacarpophalangeal Joint */

{{toplink
|backcolour =CDE472
|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

Dogs are '''digitigrade''' animals; this means that the weightbearing surface of their limbs is their digit. The canine phalanges are thus very important. They are virtually identical in their structure in the hindlimb and forelimb. The main differences are in the forelimb we have metacarpals and the metacarpophalangeal joint, the hindlimb equivalents are the metatarsals and the metatarsophalangeal joint. Also in anatomical planes we use the term palmar for forelimb and plantar for hindlimb. These terms are all interchangable in the below article depending on whether you want to talk about the fore or hindlimb.

==Bones==

====Metacarpals and Metatarsals====

* The arrangement of the metatarsals are similar to those of the metacarpals.
* They are rod shaped bones, numbered from I to V. The 1st is the most medial and is very small, the 3rd and 4th are the longest.
* The proximal base articulates with it's corresponding carpal bone and the adjacent metacarpal.
* The distal end is it's head, which is transversely cylindrical and articulates with the proximal phalanx.
* Metacarpals II - V possess a sagittal ridge on their palmar aspects.

====Phalanges====

* Proximal phalanx - of the main digits (II - V) they have a concave articular surface proximally. The palmar border has a groove to accomodate the articular surface of the metacarpus when the joint is fixed. The distal head has two convex areas seperated by a groove.
* Middle phalanx - roughly two-thirds the length of the proximal, its base has a sagittal ridge on the articular surface, which articulates with the groove of the proximal phalanx. The head resembles that of the proximal.
* Distal phalanx - made up of a cone-shaped ungual process with a distinct collar, '''ungual crest'''. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw. It articulates with the middle phalanx via a small sagittal crest.
* A bony sesamoid bone is found on the dorsal aspect of the metacarpophalangeal joint.
* The 'dew claw', metacarpal I, is normally present in the forelimb but often not in the hindlimb. It normally only consists two phalanges that resemble the proximal and distal ones.

==Joints==

====Metacarpophalangeal Joint====

* Movement - flexion and extension.
* Each joint, bar the first digit, has a pair of sesamoid bones associated with the palmar aspect of the joint. They articulate with a concave area of the proximal phalanx.
* The joint capsule runs between the four bones of the joint. Dorsally it extends under the extensor tendon, this part also intermingles with with an expanding area of the common digital extensor tendon. Distally it binds to the articular cartilage of the proximal phalanx and on the palmar aspect its dorsal attachment is level with the proximal end of the sesamoid bones.
* '''Collateral ligaments''' - bind the the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone.
* '''Palmar/intersesamoidean ligament''' - a mass of fibrocartilage that embed the sesamoid bones. The palmar aspect of it forms a groove for the deep flexor tendon to run in.
* '''Collateral sesamoid ligaments''' - connect the outer aspect of the sesamoids to the proximal phalanx.
* '''Distal sesamoid ligaments''' - a collection of ligaments that aren't well developed in the dog. They connect the distal surface of the sesamoids to the plamar aspect of the phalanx. They include the cruciate and short ligaments.
* The '''superficial transverse metacarpal ligaments''' surround the flexor tendons and their sheaths at the point of the sesamoid ligaments.
* The '''distal annular ligaments''' cross the surface of the flexor tendons and sheaths at the level of the proximal and middle phalanx.

====Proximal Interphalangeal Joint====

* Movement - flexion and extension.
* The joint capsule attaches near the articular surfaces of the proximal and middle phalanges. It extends slightly in a pouch dorsally and more extensively on the palmar aspect. The dorsal capsule is reinforced by a fibrocartilaginous nodule; the extensor tendon attaches to the capsule here.
* '''Collateral ligaments''' - connect the distal end of the proximal phalanx to the proximal end of the middle phalanx. They lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal Joint====

* Movement - extension, slight flexion.
* The joint capsule attaches to the articular periphery of the bones and has a small fibrocartilagenous bead in the palmar aspect.
* '''Collateral ligaments''' - connect the distal part of the middle phalanx to the sides of the ungual crest of the distal phalanx.
* '''Dorsal ligament''' - connects the proximal dorsal border of the extensor process of the distal phalanx. These are paired in dogs and function is to keep the claw raised until contraction of the deep digital flexor acts to overcome their tension.

==Musculature==

'''Interosseous'''
* Function - support of the metacarpophalangeal joints.
* Origin - palmar aspect of the proximal end of the metacarpal bones.
* Insertion - sesamoid bones of the metacarpophalangeal joint, it then continues as extensor branches that wrap round the dorsal aspect of the digit to join the extensor tendons.

====Forelimb====

'''Superficial digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus
* Insertion - palmar aspect of the middle phalanges

'''Deep digital flexor'''
* Function - flexion of the digits
* Origin - medial epicondyle of the humerus, proximal radius and ulna
* Insertion - palmar aspect of distal phalanges

'''Common digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - extensor process, distal phalanx

'''Lateral digital extensor'''
* Function - extensor of the digits
* Origin - lateral epicondyle of the humerus
* Insertion - proximal phalanx

====Hindlimb====

'''Long Digital Extensor'''
* Origin - extensor fossa of the lateral femoral condyle.
* Insertion - flexor aspect of the tarsus and branches which continue onto the extensor process of each of the distal phalanges.
* It divides into four branches at the level of the tarsus and are bound by the fibrous transverse bands of the proximal and distal retinaculum and are enclosed by a common synovial sheath.

'''Lateral Digital Extensor'''
* Origin - proximal fibula and lateral collateral ligament of the stifle.
* Insertion - It joins to the tendon of the long digital extensor to insert on the distal phalanx of the 5th digit.

'''Long Extensor of the first digit'''
* Origin - Proximal fibula
* Insertion - the metatarsophalangeal joint of the 2nd and 1st digit.

'''Superficial Digital Flexor'''
* Origin - Supracondylar tuberosity of the femur and is firmly united to the lateral head of the gastrocnemius.
* Insertion - Middle phalanx of the 2nd to 5th digits.
* The muscle belly converges into a strong tendon at mid-tibial level and runs medially to the gastrocnemius to the point of the hock forming a broad cap. This cap is hed in place by medial and lateral retinaculae.
* A '''synovial bursa''' lies between this cap and the calcaneal tuberosity.
* It then runs over the plantar aspect of the hock and splits twice at the level of the dorsal tarsal bones, thus forming it's four branches for insertion.

'''Deep Digital Flexor'''
* This muscle consists of three seperate heads; the '''caudal tibial muscle''', the '''lateral digital flexor muscle''' and the '''medial digital flexor muscle'''.
* '''Lateral digital flexor'''
** Origin - caudal surface of the tibia and fibula
** Insertion - its strong tendon fuses with that of the medial digital flexor tendon on the plantar aspect of the tarsus forming the deep flexor tendon. This then branches and inserts on the distal phalanx of each digit.
* '''Medial digital flexor'''
** Origin - the head of the fibula and the popliteal line of the tibia.
** Insertion - It fuses with the medial digital flexor tendon forming the deep flexor tendon.
* '''Caudal tibial'''
** Origin - caudomedially surface of the tibia
** Insertion - the tendon radiates into the medial ligaments of the tarsus and doesn't form part of the deep flexor tendon.

==Vasculature==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation==
[[Hindlimb - Anatomy & Physiology|Innervation of the Hindlimb]]

==The Canine Paw==

Composed of four weight-bearing toes, each with a claw and footpad. In addition there is a metacarpal/metatarsal footpad.

====Footpad====
* The epidermis is thick, pigmented, keratinised and hairless. It is arranged into conical papillae. '''Sweat/merocrine glands''' open onto the surface.
* The dermis of the dense connective tissue is papillated.
* The subcutaneous tissue is mainly asipose tissue with reticular, collagenous and elastic fibres. These help form '''digital cushions''' deep to the foot pad.
* The '''digital pads''' are oval shaped and support the distal interphalangeal joints. The metacarpal/metatarsal pads are heart shaped, with the apex pointing distally and support the metacarpophalangeal joints.
* A small carpal pad is present medial and distal to the accessory carpal bone.

====Claw====

* This is the horny covering of the distal phalanx. The walls of the claw, which are continuous dorsally, embrace the soft flaky horn of the sole when they touch the ground.
* The proximal part of the claw, '''coronary border''' fits between the ungual groove and the ungual crest, where it is continuous with the skin, making the '''claw fold'''.
* The periosteum of the distal phalanx is continuous with the dermis, which is arranged in '''papillae'''. These cover the dorsal aspect of the phalanx and contain the '''germinative layer'''. These are flat keratinised epidermal cells which are considered responsible for horn formation.
* The lateral and medial walls are formed by dermal laminae, instead of papillae.
* The plantar aspect of the claw is produced by papillae but this horn is very friable.
* The claws grow at rapid rate and so if they aren't worn by active wear they must be trimmed. Care must be taken as the dermis is highly vascular and bleeding will occur if cut into. To ensure that only the epidermis is cut take great care.

Bovine Hindlimb - Anatomy & Physiology

2008-09-08T15:58:07Z

Katherine: /* Musculature */

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==Pelvic Girdle and Hip==
===Bones===
The pelvic girdle is formed by two hip bones which are joined ventrally at the cartilagenous '''pelvic symphysis''' and articulate dorsally with the sacrum. The three components of each hip bone are the [[Ilium - Anatomy and Physiology|Ilium]], [[Pubis - Anatomy & Physiology|pubis]] and [[Ischium - Anatomy & Physiology|ischium]].

The bone that articulates with the hip bones to form the hip joint is the [[Femur - Anatomy & Physiology|Femur]].

====Bovine Bone Specifics====

*'''[[Ilium - Anatomy and Physiology|Ilium]]'''
**In the cow the '''tuber coxae''' is visible and is readily palpable.
**The '''sacral tuber''' has two prominences; the cranial and caudal dorsal iliac spines.
**The '''iliac crest''' is thin and concave.
**The '''ileal wing''' is orientated in a vertical manner.

*'''[[Ischium - Anatomy & Physiology|Ischium]]'''
** The '''ischial tuberosity''' is triangular in shape.

*'''[[Femur - Anatomy & Physiology|Femur]]'''
** The '''greater trochanter''' extends further dorsally compared to the femoral head.
** The medial and lateral condylar ridges are very assymetrical with the medial ridge being larger.

==Joints and Synovial Structures==

====[[Sacroiliac Joint - Anatomy & Physiology|Sacroiliac Joint]]====

* In cattle the short branch of the '''dorsal sacroiliac ligaments''' connects the sacral tuberosity to the spinous processes of the sacrum.
* The '''sacrotuberous ligament''' is a broad sheet-like ligament, which extends between the lateral aspect of the sacrum and the dorsal border of ischium and ilium. In this ligament are the '''lesser and greater ischiatic foramen''', these are present to allow for blood vessels, nerves and tendons. The caudal border of this ligament is visible subcutaneously.

====[[Coxafemoral/Hip Joint - Anatomy & Physiology|Coxafemoral/Hip Joint]]====
* The cow has the most limited range of movement compared other domestic species in its hip. This is mainly restricted to flexion and extension and is a result of the conformation of its femoral head, intraarticular ligaments and a large muscle mass around the joint.
* Cattle also have an extra acetabular notch on it's cranioventral aspect.

==Musculature==

The muscles affecting the pelvic girdle and hip can be divided into two distinct groups:

* '''[[Girdle Musculature - Anatomy & Physiology|Girdle Musculature]]'''
** '''Psoas minor''' - the muscle is marked by many tendinous intersections
** '''Iliac muscle''' - a fleshy muscle that is cross-sectionally flat cranially and round caudally. It originates from two heads; a strong lateral head from the wing of the ilium and a small medial one from the ileal shaft. They enclose the '''greater psoas''' and will unite to form a common tendon for insertion.
** '''Quadrate Lumbar''' - a thin tendinous muscle whose origin is at the proximal end of the last rib and the transverse process of the cranial lumbar vertebrae. Its insertion is the transverse processes of the caudal lumbar vertebrae and the sacral wing.

* '''[[Rump Muscles - Anatomy & Physiology|Rump Muscles]]'''
** '''Superficial gluteal'''
*** It is totally fused with the biceps muscle of the thigh forming the '''gluteobiceps'''.
** '''Middle Gluteal'''
*** Origin - the gluteal surface of the ilium. The muscle is flat at its origin and so the iliac crest is very palpable.
*** Insertion - The short portion inserts on the greater trochanter, the deep portion inserts on both the greater trochanter and distal and medial to it.
**'''Deep Gluteal'''
*** Insertion - distal to the greater trochanter on the craniolateral aspect of the femur.
**'''Tensor Muscle of the Fascia Lata'''
*** Origin - coxal tuberosity
*** Insertion - it joins the fascia lata and so indirectly attaches to the patella, lateral pattelar ligament and cranial border of the tibia. A caudodorsal detachment joins the superficial gluteal and so attaches to the greater trochanter.
** '''Gluteobiceps'''
*** Origin - Vertebral head - caudal sacral vertebrae, sacrotuberous ligament and ischial tuberosity. Pelvic head - venterolateral aspect of the ischium from the ischiatic tuberosity to the obturator foramen.
*** Insertion - the two bellies unite and the redivide at mid-tibia level. The cranial belly attaches to the fascia lata and crural fascia and so inserts on the patella, the lateral patellar ligament and the tibial tuberosity. The cranial part forms the tarsal tendon and so inserts on the calcaneal tuberosity.
*** A synovial bursa exists between the tarsal tendon and lateral femoral condyle.
** '''Semitendinous'''
*** Origin - caudoventral aspect of the ischial tuberosity.
*** Insertion - via a flat aponeurotic tendon to the cranial border of the proximal tibia, the crural fascia and the tendinous insertion of the gracilis muscle. An accessory tendon also inserts on the calcaneal tendon.
** '''Semimembranous'''
*** Origin - it just has one from the pelvic head.
** '''Sartorius'''
*** Origin - It is divided briefly into two heads because of the passage of femoral vessels.
** '''External Obturator'''
*** Cattle have an extra intrapelvic part that originates from the ilial body, the pubis and ischium. This then inserts with the rest of the muscle on the trochantic fossa.

==Proximal Hindlimb including Stifle and Tarsus==
===Bones===

The bones immediately distal to the [[Femur - Anatomy & Physiology|femur]] are the [[Hindlimb - Anatomy & Physiology#Tibia|tibia]], [[Fibula - Anatomy & Physiology|fibula]], [[Patella - Anatomy & Physiology|patella]] and some minor sesamoid bones. Some of these are involved in the stifle joint, weight-bearing and providing attachment for muscles.

Distal to these bones are the complex series of bones that make up the tarsus, these are the [[Tarsal bones - Anatomy & Physiology|tarsal bones]] and [[Metatarsals - Anatomy & Physiology|metatarsals]].

====Bovine Bone Specifics====

*'''[[Patella - Anatomy & Physiology|Patella]]'''
** The patella is extended medially by fibrocartilage.

*'''[[Hindlimb - Anatomy & Physiology#Tibia|Tibia]]'''
** The lateral aspect of the condyle has no articular facet as the [[Fibula - Anatomy & Physiology|fibula]] is directly fused to the [[Hindlimb - Anatomy & Physiology#Tibia|tibia]] at this point.
** The lateral aspect of the cochlea has an articular facet as the '''malleolar bone''', the remnant of the distal fibula, articulates here.

*'''[[Fibula - Anatomy & Physiology|Fibula]]'''
** The shaft of the fibula is totally absent.
** The proximal head is fused to the tibia.
** The distal part remains as the '''malleolar bone''', which articulates with the [[Hindlimb - Anatomy & Physiology#Tibia|tibia]].

*'''[[Tarsal bones - Anatomy & Physiology#Talus|Talus]]'''
** The trochlear ridges lie in a sagittal direction and articulates with the medial malleolus medially and the mlleolar bone laterally.
** The distal trochlear is well defined, articulating with the combined 4th and central tarsal bones.

*'''[[Tarsal bones - Anatomy & Physiology|Calcaneus]]'''
** The calcaneal tuberosity's proximal aspect is roughened and hollowed out.

*'''[[Tarsal bones - Anatomy & Physiology#Distal Row of Tarsal Bones| Distal Row of Tarsal Bones]]'''
** The cow only has three bones in the distal row, with the 1st tarsal bone being the only one left unfused. The 2nd and 3rd tarsal bones are fused together. The central and 4th tarsal bones are also fused.

===Joints and Synovial Structures===

'''[[Stifle Joint - Anatomy & Physiology|Stifle Joint]]'''

* Like the horse the cow has three patellar ligaments; the '''middle patellar ligament''', the '''lateral patellar ligament''' and the '''medial patellar ligament'''.
* The '''middle patellar ligament''' connects the the cranial aspect of the [[Patella - Anatomy & Physiology|patella]] apex to the tibial tuberosity. It has one associated bursae; one between the ligament and the groove on the tibial tuberosity. It is palpable just proximal to the tibial plateau.
* The '''medial patellar ligament''' connects the parapatellar fibrocartilage to the medial aspect of the tibial tuberosity.
* The '''lateral patellar ligament''' the cranio-lateral aspect of the [[Patella - Anatomy & Physiology|patella]] to the lateral aspect of the tibial tuberosity.
* The medial and lateral femorotibial joint capsules communicate and the medial femorotibial communicates with the femoropatellar.

'''[[Tarsal Joint/Hock - Anatomy & Physiology|Tarsal Joint/Hock]]'''

* The cow has some degree of flexion and extension in its proximal intertarsal joint.
* Like the dog the cow has an extra branch to its '''short medial collateral ligament''' that extends to the medial metatarsal bones.

===Musculature===

'''[[Muscles of the Stifle - Anatomy & Physiology|Muscles of the Stifle]]'''

'''[[Muscles of the Bovine Crus - Anatomy & Physiology|Muscles of the Bovine Crus]]'''

==Vasculature of the Hindlimb==

'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''

* The essential difference between the bovine arterial system of the hindlimb and that of the dog is the supply to the distal hindlimb.
* Unlike horses and dogs the '''saphenous artery''' doesn't have cranial and caudal branches. Instead it continues down the plantar aspect of the foot and splits into the medial and lateral plantar digital arteries.
* The '''dorsal metatarsal artery III''' sits in the groove between metatarsal III andd IV and becomes the '''dorsal common digital artery III''' near the fetlock.
* An '''interdigital artery''' exists that connects the dorsal common digital artery III and the plantar common digital artery III by passing through the interdigital space.
* There are '''axial and abaxial digits''' that run on their respective sides of the digits.

'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''

'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

Canine Hindlimb - Anatomy & Physiology

2008-09-08T13:57:43Z

Katherine: /* Canine Bone Specifics */

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[[Image:Anatomy images bone promences dog Canine 6.jpeg|right|thumb|150px|'''The Canine Hindlimb Skeleton''']]

==Pelvic Girdle and Hip==

The pelvis encircles the pelvic cavity and has several functions;
* Protection of the pelvic viscera, most importantly the reproductive and urinary organs.
* Essential in locomotion and posture
* Forms the pelvic canal, the size of which can cause problems during parturition.

===Bones===

The pelvic girdle is formed by two hip bones which are joined ventrally at the cartilagenous '''pelvic symphysis''' and articulate dorsally with the sacrum. The three components of each hip bone are the [[Ilium - Anatomy and Physiology|ilium]], [[Pubis - Anatomy & Physiology|pubis]] and [[Ischium - Anatomy & Physiology|ischium]].

The bone that articulates with the hip bones to form the hip joint is the [[Femur - Anatomy & Physiology|Femur]].

====Canine Bone Specifics====

*'''[[Ilium - Anatomy and Physiology|Ilium]]'''
**In the dog the '''tuber coxae''' isn't normally visible but is readily palpable.
**The '''tuber coxae''' has two prominences; the cranial and caudal ventral iliac spines.
**The '''sacral tuber''' has two prominences; the cranial and caudal dorsal iliac spines.
**The '''iliac crest''' is wide and convex.
**The '''ileal wing''' is orientated in an almost sagittal manner.

*'''[[Ischium - Anatomy & Physiology|Ischium]]'''
** The '''ischial tuberosity''' is linear in shape.

*'''[[Femur - Anatomy & Physiology|Femur]]'''
** The femoral head notch is circular and is situated in the centre of the head.
** There is a distinct '''neck''' connecting the femoral head to the shaft.
** The '''greater trochanter''' is level with the femoral head.

===Joints and Synovial Structures===

====[[Sacroiliac Joint - Anatomy & Physiology|Sacroiliac Joint]]====

* In dogs the short branch of the '''dorsal sacroiliac ligaments''' connects the sacral tuberosity to the mamillary processes of the sacrum.
* The '''sacrotuberous ligament''' consists of a fibrous cord between the iscial tuberosity and the transverse process of the last sacral vertebrae. (This ligament is absent in the cat.)

====[[Coxafemoral/Hip Joint - Anatomy & Physiology|Coxafemoral/Hip Joint]]====
* The dog has the greatest range of movement in this joint compared to other domestic species. It has the ability to flex, extend, rotate, adduct and abduct its whole limb because of this.

==Musculature==

The muscles affecting the pelvic girdle and hip can be divided into two distinct groups:

*'''[[Girdle Musculature - Anatomy & Physiology|Girdle Musculature]]'''
** '''Psoas Minor''' - a strong fleshy muscle. The tendon of insertion is bound to the iliac fascia and attaches to the arcuate line of the ilium.
** '''Quadrate Lumbar''' - is stronger relative to other domestic species. It has both a thoracic and lumbar part. The thoracic part originates from the bodies of the last three thoracic vertebrae and inserts on the transverse processes of the cranial lumbar vertebrae.

*'''[[Rump Muscles - Anatomy & Physiology|Rump Muscles]]'''
** '''Superficial Gluteal'''
*** Origin - gluteal fascia, lateral aspect of sacrum, sacral tuber of ilium, first caudal vertebra and the sacrotuberous ligament.
*** Insertion - via a tendon running caudodistally over the greater trochanter and inserting just distal to it.
** '''Middle Gluteal'''
*** Origin - between the iliac crest and gluteal line of the ilium.
*** Insertion - Greater Trochanter
** '''Tensor Muscle of the Fascia Lata'''
*** Origin - ventral aspect of iliac spine and aponeurosis of the middle gluteal.
*** Insertion - via the fascia lata to the patella.
*** Location - it fans out into the fascia lata and is bordered by the middlr gluteal dorsally and the sartorius muscle cranially.
** '''Biceps'''
*** Origin - Cranial superficial head - sacrotuberous ligament. Caudal head - lateral aspect of iscial tuberosity
*** Insertion - The two muscle bellies unite at an aponeurosis attached to the stifle and crural fascia. This fascia then inserts on the patella, patella ligament, and tibial tuberosity. A distal tendon of the muscle seperates from the main muscle belly and passes under the adductor and along the gastrocnemius. It moves in front of the calcaneal tendon and combining with a tendon of the semitendinous muscle inserts on the calcaneal tuberosity.
** '''Semitendinous'''
*** Origin - Caudal and ventrolateral aspect of the ischial tuberosity between the heads of the biceps and semimembranous muscle.
*** Insertion - via a strong tendon to the cranial aspect of the tendon. An accessory tendon, as mentioned above, also attaches to the calcaneal tuberosity.
** '''Semimembranous'''
*** Origin - the ventral aspect of the ischium
*** Insertion - via a short tendon to the aponeurosis of the gastrocnemius and via a longer tendon to the medial femoral condyle and medial tibial condyle.
** '''Sartorius'''
*** The cranial part originates on the iliac crest and unites with the femoral fascia and stifle fascia.
*** The caudal part originates from the ventral iliac spine and joins the aponeurosis of the gracilis on the cranial aspect of the tibia.
** '''Pectineal'''
*** Origin - a fleshy origin from the iliopubic eminence and a tendinous origin from the prepubic tendon.
*** Insertion - via a tendinous attachment to the popliteal surface of the femur.
** '''Adductor Muscles'''
*** The '''greater adductor muscle''' originates from the pelvic symphysis and prepubic tendon and inserts on the popliteal fossa and the lateral supracondylar tuberosity.
*** The '''short adductor''' originates on the pubic tubercle and inserts on the caudal aspect of the femur.
*** The '''long adductor''' is fused to the pectineal. (This is remains unfused in cats)
** '''Internal Obturator'''
*** Origin - ischium, pubis and ischiatic arch. It covers the obturator foramen.
*** Insertion - Trochantic fossa via a strong tendon that passes over the lesser sciatic notch.

==Proximal Hindlimb including Stifle and Tarsus==
===Bones===

The bones immediately distal to the [[Femur - Anatomy & Physiology|Femur]] are the [[Hindlimb - Anatomy & Physiology#Tibia|Tibia]], [[Fibula - Anatomy & Physiology|Fibula]], [[Patella - Anatomy & Physiology|patella]] and some minor sesamoid bones. Some of these are involved in the stifle joint, weight-bearing and providing attachment for muscles.

Distal to these bones are the complex series of bones that make up the tarsus, these are the [[Tarsal bones - Anatomy & Physiology|tarsal bones]] and [[Metatarsal bones - Anatomy & Physiology|metatarsals]].

====Canine Bone Specifics====

*'''[[Hindlimb - Anatomy & Physiology#Tibia|Tibia]]'''
** The cochlea has a lateral notch for the articulation with the [[fibula]].

*'''[[Fibula - Anatomy & Physiology|Fibula]]'''
** In the dog the fibula has maintained its entire length but still has reduced strength and function.
** The '''interosseous space''' seperates the [[Hindlimb - Anatomy & Physiology#Tibia|tibia]] from the fibula proximally and this gap is bridged by soft tissue.
** In thin dogs the entire bone is palpable but in heavy-set dogs only the proximal extremity is plalpable.
** The fibular head articulates with the lateral condyle of the [[Hindlimb - Anatomy & Physiology#Tibia|tibia]].

*'''[[Tarsal bones - Anatomy & Physiology#Talus|Talus]]'''
** The trochlea ridges are less pronounced and extend further distally than other species allowing for increased mobility.
** The trochlea also articulates with the distal fibula and medial malleolus.
** The body and head of the talus are seperated by a well defined '''neck'''.

*'''[[Tarsal bones - Anatomy & Physiology#Distal Row of Tarsal Bones| Distal Row of Tarsal Bones]]'''
** The dog maintains the original number of 5 bones and has the central bone, 1st, 2nd, 3rd and 4th tarsal bones.

=='''Joints and Synovial Structures'''==

'''[[Stifle Joint - Anatomy & Physiology|Stifle Joint]]'''
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]

* Posesses a '''transverse ligament''' of the menisci.
* The dog possesses one '''patellar ligament''' that is formed from the distal insertion of the quadriceps and connects the patella to the tibial tuberosity. It seperated from the joint capsule by the '''infrapatellar fat pad'''. There is often a synovial bursa between the distal part of the ligament and the tibial tuberosity.
* The medial and lateral '''femeropatellar ligaments''' extend from the patellas to the femoral epicondyles and also have attachments to the '''fabella'''. These are two small sesamoid bones that are embedded in the head of the gastrocnemius muscle.
* The joint capsule communicates directly with the femorotibial joint forming three sacs. One for the femeropatellar and one each for the medial and lateral femerotibial. These also contain the fabellae. The lateral pouch is extended to form the proximal tibiofibular joint capsule.

'''[[Tarsal Joint/Hock - Anatomy & Physiology|Tarsal Joint/Hock]]'''

* Dogs have lateral movement as well as flexion and extension in their proximal intertarsal joints.
* The '''short medial collateral ligament''' has an extra branch in dogs that extends to the medial metatarsal bones.

===Musculature===

'''[[Muscles of the Stifle - Anatomy & Physiology|Muscles of the Stifle]]'''
* The division of the four parts of the quadriceps is less well defined than in other species.
* The popliteal tendon of origin contains a sesamoid bone in carnivores.

'''[[Muscles of the Canine Crus - Anatomy & Physiology|Muscles of the Canine Crus]]'''

==Vasculature of the Hindlimb==

'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''

'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''

'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

Hindlimb - Anatomy & Physiology

2008-09-08T13:15:44Z

Katherine: /* '''Inner Pelvic Muscles''' */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can be grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect and faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores where they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via an aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that are seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lying close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:26:42Z

Katherine: /* '''The Gluteals''' */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can be grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect and faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores where they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via an aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that are seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:24:28Z

Katherine: /* Girdle Musculature */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can be grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect and faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores where they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:20:39Z

Katherine: /* Patella */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can be grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect and faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores were they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:19:21Z

Katherine: /* Stifle Joint */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can be grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores were they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:10:51Z

Katherine: /* Femur */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracapsular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally and enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression gives origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocnemius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores were they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:07:23Z

Katherine: /* Sacroiliac Joint */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracasular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally end enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression givens origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocneumius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It has a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores were they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Hindlimb - Anatomy & Physiology

2008-09-08T12:05:32Z

Katherine: /* Pubis */

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==Common structures of the Proximal Hindlimb and Pelvis==
===Ilium===
* The ilium makes up the craniodorsal part of the hip bone.
* It extends in a cranio-dorsal direction from the hip joint to the articulation with sacrum.
* It is made from a cranial wing and a caudal body.
'''''Ilial Wing'''''
* The margin of the wing is known as the '''iliac crest'''. Along the crest are two very important anatomical landmarks:
** '''Tuber Coxae''' or Coxal Tuberosity forms the palpable point of the hip.
** '''Sacral Tuber''' is the thickened mediodorsal angle of the ilial wing.
* The '''lateral''' surface of the wing provides a point of attachment for the gluteal muscles.
* The '''medial''' surface has two distinct parts:
** The lateroventral part provides the point of insertion for many pelvic muscles.
** The mediodorsal part articulate with the '''sacrum''' forming the '''sacroiliac joint'''
* The caudodorsal border of the wing is very concave and along its surface exists the '''greater sciatic notch'''. This is where the '''sciatic nerve''' runs over the ilium.
'''''Ilial Body'''''
* The only anatomical feature of note is the '''psoas tubercle''' on the ventral border. This provides attachment for the psoas muscle.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ilium|Ossification Centers of the Ilium]]'''''

===Ischium===
The Ischium can be divided into three main sections:
* The '''body'''
** Is part of the acetabulum
** The dorsal border is continuous with that of the ilium forming the '''ischiatic spine'''; this tapers towards the lesser sciatic notch.
* The '''caudal plate'''
** Extends cranially into the symphysial and acetabular branches, which form the caudal borders of the '''obturator foramen'''.
** The caudal section is thickened forming the '''ischial tuberosity'''. This is a visible landmark in most animals.
** The medial caudal borders meet in a concave fashion forming a broad and deep notch called the '''ischial arch'''.
* The '''medial branch'''
** This forms the caudal section of the pelvic symphysis
'''''[[Ossification Hindlimb - Anatomy & Physiology#Ischium|Ossification Centers of the Ischium]]'''''

===Pubis===
*The pubis is a L shaped bone that makes up one of the three bones of the pelvis.
*It consists of three parts:
**'''Body'''
**Transerse '''acetabular branch''' - the cranial edge of which is the '''pectin of pubis''' and forms the '''iliopubic emminence''', to which some of the abdominal muscles attach.
**Sagittal '''symphysial branch'''
*The two pubis fuse at the cranial section of the '''pubic symphysis'''. Lying off the ventral surface of the symphysis is the '''ventral pubic tubercle'''.
*The pubis forms more than half the '''obturator foramen'''. This is an opening in the pelvic floor that allows the obturator nerve to pass through it; the foramen is closed by musculature and soft tissue.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Pubis|Ossification Centers of the Pubis]]

===Femur===
The femur is the strongest of the long bones and provides the origin and attachment for many muscles and tendons. This means that it is charcacteristically modelled for each species. Despite this it can be divided into three basic parts:
'''''The Femoral Head'''''
* The head is offset from the main shaft of the femur, points in a medial direction and articulates with the acetabulum.
* It has a hemispherical articular surface with an associated '''notch''', ''fovea capitis'', which provides attachment for the '''intracasular ligament'''.
* Lateral to the head is the '''greater trochanter'''. This process provides attachment to the gluteal muscles.
* The '''trochantic fossa''' seperates the greater trochanter and the neck of the femur. It provides a site of insertion for the deep hip muscles.
* The '''lesser trochanter''' is a smaller process on the medial side that provides a site of attachment for the iliopsoas.
'''''Femoral Shaft'''''
* The caudal surface is roughened proximally and is framed by the '''medial and lateral lips'''
* These lips extend distally end enclose the '''popliteal surface'''. They also provide attachment for the adductor muscles.
'''''Distal Extremity'''''
* This consists of the '''medial and lateral condyles''' caudally and a trochlea cranially.
* The condyles articulate with the tibia and menisci to form the '''femorotibial joint'''.
* The '''intercondylar fossa''' lies between the condyles and is seperated from the polpiteal surface by the '''intercondylar line'''.
* Both condyles are roughened on their abaxial surfaces providing attachment for the collateral ligaments of the stifle joint.
* The '''extensor fossa''' is one of a pair of depressions on the lateral condyle. It is the more cranial of the two and forms an attachment point for the long digital extensor and third perineal muscle. The caudal depression givens origin to the popliteal.
* On the caudal aspect of each condyle are facets for the articulation with the '''fabellae'''. These are sesamoid bones that are embedded in the tendinous insertion of the '''gastrocneumius'''.
* The '''trochlea''' is made up of two ridges and a groove that articulate with the '''patella''' to form the '''femeropatellar joint'''.
'''''[[Ossification Hindlimb - Anatomy & Physiology#Femur|Ossification Centers of the Femur]]'''''

==Joints of the Proximal Hindlimb==
===Sacroiliac Joint===
*This is a '''synovial joint''' that is formed by the articulations between the auricular surfaces of the ilial wing and the sacrum.
*It had a joint capsule that tightly surrounds the joint and is strengthened by the '''ventral sacroiliac ligaments'''.
*The sacroiliac ligaments are:
**'''Interosseous sacroiliac ligaments''' - these lie between the iliac tuberosity and the dorsal aspect of the sacral wing.
**'''Dorsal Sacroiliac ligaments''' - this is made up of two branches. The short branch connects the sacral tuber to either the mammilary processes (carnivores and pigs)or to the spinous processes (ruminants and horses) of the sacrum. The long branch connects the sacral tuber to the lateral aspect of the sacrum.
*The '''sacrotuberous ligament''' is highly variable among species.

===Coxafemoral/Hip Joint===
* This is a spheroidal joint formed by the femoral head and the '''acetabulum'''.
* The '''acetabulum'''
** Formed by all three pelvic bones and an additional '''small acetabular bone''' in carnivores that is present in carnivores.
** The craniolateral part is made by the ilium, the caudolateral part by the ischium and the medial part by the pubis.
** The cavity of the acetabulum consists of a peripheral '''articular lunate surface''' and the non-articular '''acetabular fossa''' in it's centre.
** The lunate surface is crescent shaped and has on its medial aspect the '''acetabular notch'''.
** Cattle also have a '''cranioventral notch ''' present.
** The '''acetabular lip''' is a band of fibrocartilage that lies on the acetabular rim, thus deepening the acetabulum.
* The joint capsule is large and attaches to the acetabular lip.
* The '''ligament of the femoral head''' connects the fovea in the head, by running through the acetabular notch, to the acetabular fossa. It is covered by a synovial membrane and for the majority is intracapsular.
* The '''acessory ligament of the femur''' is only present in the horse. It originates from the straight muscle of the abdomen and passes through the acetabular notch to finally attach in the fovea of the femoral head.
* The '''transverse acetabular ligament''' crosses the acetabular notch and ensures that the other two ligaments remain in their notch.

==Common Structures of the Distal Hindlimb==
===Tibia===
The tibia is one of the major weight bearing bones of the hind limb and is involved in both the stifle and hock. The tibia can be divided into three distinct sections:

'''''Proximal Extremity'''''
* It is three sided and has two condyles which are seperated by the '''popliteal notch''' on its caudal aspect.
* The condyles have an articular surface which articulates with its corresponding femoral condyle or the distal surface of the meniscus.
* In between these articular surfaces lies the '''intercondylar eminence'''. The '''central intercondylar area''' divides this into a '''higher medial part''' and a '''lower lateral part'''.
* Cranial and caudal to the eminence are depressions where ligaments attach.
* The lateral side of the condyle has an articular facet for the articulation with the fibula.
* The '''extensor groove''' is a large notch on the craniolateral aspect which allows passage of the long digital extensor muscle.
'''''Tibial Shaft'''''
* It is craniocaudally compressed.
* The '''tibial tuberosity/tibial crest''' projects cranially from the proximal part of the shaft and is an important palpable landmark.
* The '''cranial border of the tibia''' is an extension of the crest distally. It divides the cranial aspect of the shaft in two. The medial aspect is subcutaneous and the lateral aspect is covered in muscles.
'''''Distal Extremity'''''
* This carries the '''cochlea''' which has two grooves divided by a ridge.
* This central ridge is directed sagittally in most species.
* The cochlea articulates with the trochlear ridges of the talus.
* The '''medial malleolus''' lies on the medial side of the cochlea and is a bony protuberence.
* The lateral aspect of the cochlea is highly variable in domestic species.

'''''[[Ossification Hindlimb - Anatomy & Physiology#Tibia|Ossification Centers of the Tibia]]'''''

===Fibula===
The fibula lies laterally to the tibia and proximally doesn't interact with the stifle joint. The fibula consists of a '''proximal head''', a '''neck''', a '''shaft''' and a distal extremity/'''lateral malleoulus'''.
During evolution the fibula has been reduced in size and so also in relative strength and function. The amount of reduction is highly variable in domestic species.

===Tarsal bones===
The '''tarsus/hock''' is made up of two bones that lie between the crus and metatarsals.
The proximal row is made of the '''talus''' and '''calcaneous''' and articulate with the tibia forming the '''tarsocrural joint'''.
The distal row is made up of the central, 1st, 2nd, 3rd and 4th tarsal bones. The pattern of these bones is highly variable amongst domestic species. But in general they articulate with proximal row forming the '''tarsocrural joint''' and with the metatarsal bones forming the '''tarsometatarsal joint'''.

'''''Talus'''''
* The largest bone of the tarsus and is the medial bone of the proximal row.
* It can be divided into three distinct areas; the compact '''body''', the '''trochlea''' and the '''head'''.
* The '''trochlea''' has prominent sagittal ridges dorsoproximally that articulate with the sagittal grooves and intermediate ridge of the distal end of the '''tibia'''.
* The cylindrical '''head''' is a smaller distal trochlea that articulates with the '''central tarsal bone'''. The plantar and lateral sides articulate with the '''calcaneous'''.
'''''Calcaneus'''''
* It lies laterally and plantar to the '''talus'''.
* It articulates medially and dorsally to the talus and distally towards the 4th tarsal bone.
* It has a proximal plantar projection called the '''calcaneal tuberosity''', it is this that forms the palpable '''point of the hock'''. It acts as a lever for muscles involved in hock extension.
* The '''susentaculum tali''' lies on the medial aspect of the distal portion of the calcaneus. It supports the deep digital flexor tendon and overlaps the talus on its plantar side.
'''''Distal Row of Tarsal Bones'''''
* These are highly variable amongst species but are discussed on their relevant pages.

===Metatarsal bones===

==Joints of the Distal Hindlimb==
===Stifle Joint===
[[Image:stifle anatomy.jpg|thumb|right|150px|The Stifle, Cranial Caudal View - Copyright RVC]]
A composite, incongruent hinge joint made up of the '''femerotibial joint''' and '''femeropatellar joint'''.

'''''Femerotibial Joint'''''
* Essentially this joint is formed between the femoral condyles and the proximal end of the tibia.
* A '''meniscus''' exists between each condyle and the tibia to compensate for any incongruency of the articular surfaces. The meniscus is a semilunar fibrocartilage with a thick, convex peripheral border and central thin, concave border. The surface facing the femoral condyles is concave and facing the tibia it is flattened.
* As a condylar joint the principal movements are '''flexion''' and '''extension''', but due to the presence of the menisci there is a limited amount of rotation.
* The '''fibrous layer''' of the joint capsule attaches to the margins of the articular surfaces and menisci and so completely encircles the femoral condyles.
* The '''synovial layer''' of the capsule covers the cruciates and forms a partition between the medial and lateral parts of the joint. These sacs are further seperated by the menisci into a proximal and distal communicating compartments.
* The lateral femerotibial joint contains two pouches; one ensheathes the origin of the tendinous origin of the politeal and the other ensheathes the origin of the long digital extensor at the extensor fossa.
'''''Meniscal Ligaments'''''
* '''Cranial tibial ligaments of the menisci''' - connecting the cranial aspect of the menisci to the medial and lateral cranial intercondyloid area of the tibia.
* '''Caudal tibial ligaments of the menisci''' - the medial ligament connects the caudal angle of the medial meniscus to the caudal intercondyloid area of the tibia. The lateral ligament connects the caudal angle of the lateral meniscus to the popliteal notch of the tibia.
* '''Femoral ligament of the lateral meniscus''' - connects the caudal angle of the lateral meniscus to the inside aspect of the medial femoral condyle.
* '''Transverse ligament''' - connects the cranial angles of the lateral and medial menisci. Found in carnivores and cattle.
'''''Femerotibial ligaments'''''
*'''Lateral and Medial Collateral Ligaments''' - The lateral connects the lateral epicondyle of the femur to both the lateral condyle of the tibia and the head of the fibula. The medial connects the medial epicondyle of the femur to just distal to the margin of the medial condyle of the tibia. This ligament fuses with the joint capsule and medial meniscus.
*'''Cranial and Caudal Cruciate Ligaments''' - These ligaments sit in the intercondyloid fossa of the femur inbetween the two synovial sacs. The cranial connects the lateral femoral condyle to the central intercondylar area of the tibia. The caudal connects the medial femoral condyle to the popliteal notch of the tibia.
*'''Oblique Popliteal Ligament''' - This is made of fibrous strands that are embedded in the joint capsule and run in latero-proximal to medial-distal direction.
'''''Femeropatellar Joint'''''
* This joint is formed between the articular surfaces of the patella and femur. The ligaments of this joint can grouped as the '''femeropatellar ligaments''' and the '''patellar ligament'''.
* Both these groups of ligaments are highly species specific and are discussed on the species pages.

===Patella===
* This is the largest '''sesamoid bone''' and lies in the tendinous insertion of the quadriceps.
* The articular surface is on the caudal aspect faces the femur. The free surface faces cranial and is palpable in all species.
* The base is at the proximal end and is rough due to muscular attachments.
* The apex is at the distal end.

===Tarsal Joint/Hock===
A '''composite joint''' between the tibia, fibula, tarsal bones and metatarsals which has four levels of articulation. The joint capsules' '''fibrous layer''' extends from the distal crus to the proximal metatarsal and thus covers the whole tarsus. The '''synovial layer''' forms four synovial sacs for each level of articulation. The points of articulations are: '''Tarsocrural Joint''', '''Proximal Intertarsal Joint''', '''Distal Intertarsal Joint''' and the '''Tarsometatarsal Joint'''. The intratarsal joints are very closely apposed and so allow very little movement.
'''''Tarsocrural Joint'''''
* A cochlear joint formed by the articulation of the trochlea of the talus and the distal end of the tibia. And the articulation between the calcaneous and the distal end of the fibula or lateral malleolus (cows).
* It has a large joint capsule that communicates with the proximal intertarsal joint. It has two plantar pouches that extends proximally above the medial and lateral malleoli. It also has a dorsal pouch that continues under the medial tendon of the cranial tibial muscle.
'''''Proximal Intertarsal Joint'''''
* Proximally the talus and calcaneus articulate and distally the central and forth tarsal bone articulate.
* The extent of direction of movement is species variable.
* A rigid joint formed by the central tarsal bone and the small tarsal bones distally.
'''''Tarsometatarsal Joint'''''
* This is the articulation between the distal tarsal bones and the metatarsal bones.
'''''Ligaments of the Tarsus'''''
* '''Long lateral collateral ligament''' connects the lateral malleolus to the proximal part of the lateral metatarsal bones. Along it's course it attaches to the lateral tarsal bones.
* '''Short lateral collateral ligament''' connects the lateral malleoulus to the calcaneus and the talus and lies deep to the long lateral collateral ligament.
* '''Long medial collateral ligament''' connects the medial malleolus to the proximal part of the medial metatarsal bones. Along it's course it attaches to the medial tarsal bones.
* '''Short medial collateral ligament''' connects the medial malleolus to the calcaneus and the talus and is deep to the long ligament.
* '''Dorsal tarsal ligament''' is a triangular sheath, which is spread between the medial part of the talus, the central and 3rd tarsal bones and the 3rd and 4th metatarsal bones.
* '''Long plantar ligament''' is a strong ligament connecting the calcaneus to the central and 4th tarsal bones and the proximal part of the 3rd and 4th metatarsal bones.
* Numerous short ligaments bridge the joint spaces in the intratarsal joints.
* Strong fascia help keep tendons in place and are partially fused to the joint capsule. The most important are the '''proximal extensor retinaculum''', which holds down the tendon of the long digital extensor and the cranial tibial muscles, and the '''distal extensor retinaculum''', which holds the tendon of the long digital extensor in place.

==Muscles of the Hindlimb==
===Girdle Musculature===
*These muscles arise from the ventral aspect of the lumbar vertebrae and will insert on either the pelvis or femur. They are also known as the '''sublumbar muscles'''.
* Their main function is to:
** Stabilise the vertebral column and pelvis during locomotion.
** Control dorsiflexion and ventriflexion of the spine.
* The '''Psoas Minor'''
** Function: flexion of the vertebral column during the stance phase. Stabilisation of the vertebral column.
** Origin: 2nd-3rd caudal thoracic vertebrae on their ventral aspect and the 4th/5th cranial lumbar vertebrae
** Insertion: via a strong tendon to the psoas tubercle of the femoral shaft.
* The '''Iliopsoas''' - the strongest muscle of the girdle
** Function: Flexion of the hip and outward rotation of the stifle. ie. draws hindlimb forward
** In all animals, except carnivores were they are fused, the muscle can be divided into two distinct parts.
** The '''Greater Psoas''' - the lumbar portion.
*** Origin: last thoracic vertebrae and ribs and the bodies and transverse processes of the lumbar vertebrae.
*** Insertion: Incorporates with iliac muscle and inserts on the lesser trochanter.
*** It is positioned dorsally to the psoas minor and ventral to the quadrate lumbar muscle.
** The '''iliac muscle'''
*** Origin: wing and shaft of ilium
*** Insertion: via the common iliopsoas tendon to the lesser trochanter of the femur.
*** The muscle passes through the '''muscular lacuna'''; an opening between the os coxae laterally and caudally, the rectus abdominus medially and the iliac fascia cranially.
* The '''quadrate lumbar''' muscle
** Function: stabilisation of the lumbar vertebral column
** Origin: Ventral aspect of the transverse processes of the lumbar vertebrae and the proximal ends of the ribs
** Insertion: Ventral aspect of the wings of the ilium and sacrum.

===Rump Muscles===
The rump muscles main function is to extend the hip and some also extend the stifle and tarsus. They can be grouped into four distinct groups; the gluteals, the hamstrings, the medial muscles of the thigh and the inner pelvic muscles.

===='''The Gluteals'''====
They lie over the lateral and caudal aspect of the pelvic wall and extend between the thigh and ilium.
'''''Superficial Gluteal Muscle'''''
* This muscle shows great species variance and will be explained on their respective homepages.
* Function - Extension of the hip, also retraction of the limb and supports outward rotation.
'''''Gluteofemoral Muscle'''''
* This muscle only exists in the cat.
* Function - Retraction and abduction of the limb and hip extension
* Origin - 2nd-4th caudal vertebrae
* Insertion - Lateral aspect of patella and fascia lata via a aponeurosis
* Location - Between the superficial gluteal muscle and biceps muscle of the thigh.
'''''Middle Gluteal Muscle'''''
* This muscle also shows great species variance. Though all species have a superficial and deep portion that a seperated by a tendinous sheet. Both tendons on their site of insertion are protected by a synovial bursa.
* Function - most powerful extensor of the hip, also abducts and retracts the limb.
'''''Piriform Muscle'''''
* This is fused to the middle gluteal muscle except in carnivores.
* Function - Extensor of hip and abducter of the limb.
* Origin - last sacral vertebrae and sacrotuberous ligament.
* Insertion - just distal to the greater trochanter on the lateral aspect of the femur.
* Location - caudal and medial to the middle gluteal and is covered by the superficial gluteal.
'''Deep Gluteal Muscle'''
* Function - abduction of the limb.
* Origin - lateral aspect of the ilial shaft
* Insertion - via a short tendon to the greater trochanter.
'''''Tensor Muscle of the Fascia Lata'''''
* This muscle shows great species variance.
* Function - flexion of the hip and extension of the stifle.

===='''The Hamstrings'''====
These muscles cover the caudal aspect of the thigh and are multi-articular. They originate near the ischium and extend to the tibia and have some tendinous components that will make up the '''common calcanean tendon'''.

'''''Biceps Muscle of the thigh'''''
* The largest and most lateral of the muscles, it is superficial and covered only by fascia and skin.
* It consists of cranial part arising from the sacrum and sacrotuberous ligament and a small caudal part arising from the ischium.
* The muscle is composed of multiple parts and has different points of insertion in different species.
* Function - Extension and abduction of the limb. The cranial part extends the hip and stifle, though the caudal part extends the hip but flexes the stifle. It also causes tarsal extension.
* See species pages as is very species specific.
'''''Abductor muscle of the thigh'''''
* Only present in carnivores
* Function - abduction of the limb
* Origin - sacrotuberous ligament
* Insertion - crural fascia
'''''Semitendinous'''''
* Function - extends the hip, stifle and tarsus when the foot makes contact with the ground, therefore propulsing the animal. On a non-weightbearing leg it flexes the stifle and rotates the leg back and out.
* Origin - the ischial tuberosity ('''pelvic head''')
* Insertion - cranial margin of the tibia and a tendinous insertion on the calcaneal tuberosity.
'''''Semimembranous'''''
* The most medial of the hamstrings.
* Function - Extension of the hip and stifle in a weightbearing stance. On a non-weightbearing limb it adducts and retracts the limb.
* Origin - can be from either just the pelvic head or from the pelvic head and '''vertebral head'''. This is dependent on species.
* Insertion - onto the medial condyle of the femur and the medial condyle of the tibia.

===='''Medial Muscles of the Thigh'''====
This muscle groups main functions are to adduct the limb and to prevent unwanted abduction. They lie between the pelvic floor and the medial aspect of the femur.

'''''Sartorius'''''
* Function - flexion of the hip, advancement and abduction of the limb. It can also extend the hip via its attachments to the crural fascia and stifle fascia.
* Origin - Coxal tuberosity; ilial shaft or tendon of psoas minor
* Insertion - Deep fascia of the leg
* Location - superficially on the craniomedial border of the thigh as a strap like muscle.
'''''Gracilis'''''
* Function - adductor of the limb, extends the stifle.
* Origin - from an aponeurosis of the pelvic symphysis, the insertional tendons of the straight muscle of the abdomen. A tendinous plate is formed between the two aponeurosi of the gracilis' on which the adductor muscles originate.
* Insertion - An aponeurotic insertion with the crural fascia that attaches to the tibial crest.
* Location - broad muscular sheet on the caudal aspect of the medial part of the thigh.
'''''Pectineal Muscle'''''
* Function - flexor of the hip, adductor and supinator of the limb.
* Origin - iliopubic eminence of pelvic floor
* Insertion - medial border of the femur
* Location - a fusiform muscle extending between the pecten of the pubis, the pelvic floor and the femur.
'''''Adductor Muscles'''''
* Function - adduction of the limb, can also retract the limb
* Origin - the tendinous plate of the gracilis muscles.
* Insertion - medial aspect of the femur, fascia and ligaments of the medial aspect of the stifle.

===='''Inner Pelvic Muscles'''====
This set of muscles are a rather mixed group of small muscles lieing close to the hip joint. They lie between the pelvis and trochantic fossa of the femur.

'''''Internal Obturator'''''
* Only exists in carnivores and horses.
* Function - extension of the hip and rotation of the femur laterally.
* Origin and insertion - are both dependent on species involved.
'''''External Obturator'''''
* Function - supinator of the femur and adductor of the limb
* Origin - the ventral pelvic surface close to the obturator foramen
* Insertion - trochantic fossa
'''''Gemellus'''''
* Function - rotation of the limb laterally
* Origin - ischiatic spine
* Insertion - unites partially with the internal obturator and so inserts on the trochantic fossa.
'''''Quadrate Muscle'''''
* Function - extension of the hip and retraction of the limb
* Origin - ventral aspect of ischium
* Insertion - trochantic fossa
'''''Articular muscle of the hip joint'''''
* Only in carnivores and horses
* Function - causes tension of the joint capsule and thus helps prevent damage to the peri-articular structures.
* Origin - Hip joint capsule

===Muscles of the Stifle===
Many of the muscles of the hip (see [[Hindlimb - Anatomy & Physiology#Girdle Musculature|Girdle Musculature]] and [[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]) act on the stifle by inserting on structures involved with the stifle or are distal to it. There are only really two muscles that act solely on the stifle; the '''quadriceps''' and the '''popliteal'''.

'''''Quadriceps'''''
* This muscle forms the main muscle bulk on the cranial aspect of the thigh but is covered by the tensor muscle of the fascia lata, the sartorius and the medial femoral fascia.
* The quadriceps are the main extensors of the stifle and the straight muscle also flexes the hip.
* The muscle consists of four parts that have seperate points of origin but have a common single tendon, the '''patella tendon''' that inserts onto the patella and '''tibial tuberosity'''.
* The four parts are:
**'''Lateral Vastus''' - On the craniolateral side of the femur originating from the lateral aspect of the proximal femur.
**'''Medial Vastus''' - on the craniomedial side of the femur originating from the medial aspect of the proxial femur.
**'''Intermediate Vastus''' - on the cranial surface of the femur it is totally covered by the other quadriceps muscles and is the weakest muscle of the quadriceps.
**'''Straight muscle/Rectus femoris''' - originates from the ilial shaft cranial to the acetabulum and runs down to the patella tendon between the two bellies of the lateral and medial vastus.
'''''Popliteal'''''
* Function - flexor of the stifle and pronator of the leg.
* Origin - a tendinous origin from the lateral condyle of the femur.
* Insertion -a broad tendon on the medial and caudal surface of the proximal tibia.
* Location - On the caudal aspect of the stifle and runs under the lateral collateral ligament before it inserts.

==Vasculature of the Hindlimb==
*'''[[Arteries of the Hindlimb - Anatomy & Physiology|Arteries of the Hindlimb]]'''
*'''[[Veins of the Hindlimb - Anatomy & Physiology|Veins of the Hindlimb]]'''
*'''[[Lymphatics of the Hindlimb - Anatomy & Physiology|Lymphatics of the Hindlimb]]'''

==Innervation of the Hindlimb==

The nerves that supply the hindlimb arise from the lumbosacral plexus that lies on the medial wall of the pelvis. These nerves are:

'''Femoral Nerve'''
* Origin - cranial part of the lumbosacral plexus, L4 and L5. (Sometimes L3 and L6)
* Motor innervation - Quadriceps and iliopsoas muscle.
* Sensory innervation - the medial aspect of the limb.
* Route - through the iliopsoas.

'''Obturator Nerve'''
* Origin - middle part of the lumbosacral plexus, L5 and L6.
* Motor innervation - adductor muscles; external obturator, adductor and gracilis.
* Sensory innervation - none
* Route - through the iliopsoas, medial to the ilial shaft and then through the obturator foramen.

'''Gluteal Nerves'''
* Origin - L6, L7 and S1
* Motor innervation - gluteal muscles, tensor fascia lata, biceps femoris and semitendinosus.
* Sensory innervation - none
* Route - direct to the gluteals.

'''Sciatic Nerve'''
* Origin - L6, L7, S1 and S2.
* Motor innervation - biceps femoris, semintendinosus, semimembranosus.
* Sensory innervation - the nerve divides into the tibial and fibula nerves where cutaneous fibres run.
* Route - the largest nerve in the body. It leaves the pelvis at the greater sciatic notch and curves in a ventral caudal direction around the hip joint. It runs distocaudally over the femur between the biceps femoris medially and the adductor, semimembranosus and semitendinosus muscles medially. It then divides into the tibial and fibular nerves.

'''Tibial Nerve'''
* Origin - the sciatic nerve.
* Motor innervation - extensors of the hock, flexors of the digits, popliteal muscle.
* Sensory innervation - caudal aspect of the limb below the stifle.
* Route - it runs caudal to the stifle joint into the muscle.

'''Fibular (Peroneal Nerve)'''
* Origin - the sciatic nerve.
* Motor innervation - flexors of the hock, extensors of the digits.
* Sensory innervation - cranial and lateral aspect of the limb.
* Route - caudal to the stifle.

==Species Specifics==
*[[Canine Hindlimb - Anatomy & Physiology|Canine Hindlimb]]
*[[Equine Hindlimb - Anatomy & Physiology|Equine Hindlimb]]
*[[Bovine Hindlimb - Anatomy & Physiology|Bovine Hindlimb]]

Bovine Forelimb - Anatomy & Physiology

2008-09-08T11:56:59Z

Katherine: /* Muscles of the Carpal and Digital Joints */

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==Structures of the Proximal Forelimb and Shoulder==

===Scapula===
*The ox possesses a small '''tuber scapular'''
*It has '''acromion''' present
*It has extensive scapular cartilage

===Humerus===
*The humerus is essentially the same conformation as that of the dog.

===Radius and Ulna===
*These are complete bones in the ox but are entirely fused
*There is a proximal and distal interosseous space which are the only two places where the shafts are seperated
*The ulna's proximal end is caudal to the radius and it's distal end forms the lateral styloid process, distal to the radius and articulating with the ulnar carpal bone.

==Joints of the Proximal Forelimb==
===Shoulder Joint===

*The joint capsule attaches a very short distance from the periphery of the articular surfaces.
*The '''intertubercular (bicipital) bursa''' lies between the humeral tubercles cushioning the bicipital tendon.
*The bursa and tendon are held in place by the '''transverse humeral retinaculum''' running between the greater and lesser tubercles of the humerus.

===Elbow Joint===

*The joint capsule attaches to the articular surface of the condyle, the periphery of the olecranon fossa and the articular cartilage of the trochlear notch of the ulna. It fuses with the collateral ligaments.
*Paired collateral ligaments attach the epicondyles to the tuberosities of the radius and ulna.

==Structures of the Distal Forelimb==

===Carpal bones===

Carpal bones comprise two rows:
*Proximally, (mediolaterally), radial, intermediate, ulnar and accessory bones
*Distally, 1st is missing, 2 and 3 are fused

===Metacarpal bones===

These are covered in detail in the [[Bovine Phalanges - Anatomy & Physiology|bovine phalanges]] section.

==Joints of the Distal Forelimb==
===Carpal Joint===

The carpal joint is a compound joint composed of:
*The '''antebrachiocarpal joint''' between the radius/ulna and the proximal carpal bones
*The '''middle carpal joint''' between the two rows of carpal bones
*The '''carpometacarpal joint''' between the distal carpal bones and the proximal metacarpals

The joint is a synovial joint, comprised of a common outer fibrous capsule and three inner synovial pouches, one for each joint.
*'''Collateral ligaments''' extend from the radius to the metacarpal bones on the medial and lateral aspect of the carpus.
*The carpal canal houses both the deep digital flexor tendon and the deep branch of the superficial digital flexor.

==Muscles of the Forelimb==
===Extrinsic Musculature===

These muscle are responsible for joining the forelimb to the trunk, forming a synsarcosis rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs as well as stabilize the scapula.

'''''Trapezius''''': Accessory n.
*Origin: mid-dorsal raphe and supraspinous ligament
*Insertion: spine of the scapula
*Body: two parts, cervical and thoracic separated by aponeurosis
*Action: raises scapula against the trunk and swings cranially to advance the limb

'''''Brachiocephalic m.''''': Accessory n.
*Two parts separated by the clavicle where it exists
*Origin: occipital bone, nuchal ligament, mastoid process
*Insertion: deltoid tuberosity and fascia of limb
*Actions:
**advances the limb and extends the shoulder joint when limb is in motion
**draws head and neck ventrally when limb is fixed

'''''Omotransversarius''''': Accessory n.
*Origin: transverse processes of the atlas
*Insertion: acromion and spine of scapula
*Action: advancing the limb
*Innervation

'''''Latissimus dorsi''''': local branch of brachial plexus
*The '''broadest muscle of the back'''
*Origin: thoracolumbar fascia
*Insertion: teres tuberosity of the humerus
*Actions: antagonist to the brachiocephalic m.
**cranial fibers strap scapula to the chest
**retracts free limb and flexes shoulder joint
**draws trunk forward over the fixed limb

'''''Pectoral mm.''''': brachial plexus
*Two superficial parts, cranial and caudal, these aren't very distinct in the ox
**Origin: cranial sternum
**Insertion:
***cranial ('''descending'''): crest of the humerus distal to the deltoid tuberosity
***caudal ('''transverse'''): covers elbow joint to insert on the medial fascia of the forearm
**Action: adduct the forelimb, assist in protraction and retraction
*One deep part ('''pectoralis profundus'''), with cranial and caudal parts
**Origin: ventral sternum and adjacent cartilage
**Insertions:
***cranial (subclavius): supraspinatus m.
***caudal (pectoralis ascendens): lesser tubercle of the humerus
**Actions:
***slinging trunk between forelimbs
***may also retract free limbs
***draw trunk forward when limb is fixed

'''''Serratis ventralis''''': branch of brachial plexus
*Origin: C4 to 10th rib
*Insertion: medial scapula and scapular cartilage
*Action: supporting the weight of the trunk
**reinforced by strong fascia
**cervical portion can retract the limb
**caudal portion can advance the limb

'''''Rhomboids''''': brachial plexus,
*Origin: nuchal ligament
*Insertion: dorsal border and adjacent scapula
*Action: retracting the limb, may also raise limb

===Intrinsic Musculature===
====Muscles of the Shoulder====
These muscles are grouped:
*Lateral:'''Supraspinatus ''' and '''Infraspinatus''', Suprascapular n. of the brachial plexus
**Origin: the fossae of the scapula
**Insertion: both tubercles of the humerus
**Action: brace the shoulder
**Clinical significance: bursa between the tendon of the infraspinatus and lateral tubercle of the humerus can be the site of inflammation
*Medial:
**'''Supscapularis''': Subscapular n. from the brachial plexus
***Origin: Deep surface of the scapula
***Insertion: medial tubercle of the humerus
***Action: braces medial shoulder joint, potential adductor
**'''Coracobrachialis''': Musculocutaneous n. of the brachial plexus
***Origin: medial supraglenoid tubercle
***Insertion: proximal shaft of the humerus
***Action: fixator
*Caudal (Flexors): Axillary n. of the brachial plexus
**'''Deltoids'''
***Origin: caudal border and spine of the scapula, acromion
****Two heads of origin
***Insertion: deltoid tuberosity on the humerus
**'''Teres Major'''
***Origin: dorsal part of the caudal scapula
***Insertion: teres tuberosity midway down humerus
**'''Teres Minor'''
*There are no defined extensors of the shoulder. Those involved (brachiocephalic m., biceps brachii, supraspinatus, and ascending pectorals) have other, more primary roles.

====Muscles of the Elbow====
''Extensors'': Radial n. from the brachial plexus
*'''Triceps brachii''': Three heads,the medial branch is the most developed
**Long head: caudal margin of the scapula
**Lateral, medial, and accessory heads: shaft of the humerus
**Insertion: olecranon, proteced by tricipital bursa against the bone and subcutaneous bursa against the skin
*'''Tensor fasciae antebrachii'''
**Overlies triceps extending from scapula to olecranon

''Flexors'': Musculocutaneous n. from the brachial plexus
*'''Biceps brachii'''
**Origin: supraglenoid tubercle of the scapula
**Insertion: medial tuberosity of proximal radius and adjacent ulna
**Runs through the intertubercular groove of the humerus
*'''Brachialis'''
**Origin: proximocaudal humerus
**Insertion: spirals to insert next to biceps

====Muscles of the Carpal and Digital Joints====
''Extensors'': Radial n. from the brachial plexus
*Craniolateral position on the forearm
*Almost all originate from the lateral epicondyle of the humerus
*'''Extensor carpi radialis''': most medial, inserts on 2nd/3rd metacarpal bone
*'''Ulnaris lateralis''': most lateral, inserts on accessory carpal bone
*'''Extensor carpi obliquus''': aka '''abductor pollicis longus'''
**Origin: cranial radius
**Insertion: most medial metacarpal bone
*Last two may also serve in medial deviation of the foot
*'''Common Digital Extensor'''
**Insertion: extensor process of the distal phalanx of each digit
*'''Lateral Digital Extensor'''
**Insertion: dorsal proximal phalanges
*'''Medial Digital Extensor'''
**Insertion: middle and distal phalanges

''Flexors'': Median or Ulnar n. of the brachial plexus
*Caudal position on the forearm
*Originate from the caudal medial epicondyle of the humerus
*'''Flexor carpi radialis''': most medial, inserts on upper 2nd/3rd metacarpal bone
*'''Flexor carpi ulnaris''': most lateral, inserts on the accessory carpal bone
*'''Superficial Digital Flexor'''
**Insertion: palmar surface of middle phalanges
*'''Deep Digital Flexor'''
**Passes through carpal canal before branching and continues to palmar distal phalanges

''Interosseus muscles''
*This is covered in more detail in the [[Bovine Phalanges - Anatomy & Physiology|bovine phalanges]] section.

==Vasculature of the Forelimb==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''

Bovine Forelimb - Anatomy & Physiology

2008-09-08T11:45:06Z

Katherine: /* Extrinsic Musculature */

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|pagetype =Anatomy
|sublink1=Forelimb - Anatomy & Physiology
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==Structures of the Proximal Forelimb and Shoulder==

===Scapula===
*The ox possesses a small '''tuber scapular'''
*It has '''acromion''' present
*It has extensive scapular cartilage

===Humerus===
*The humerus is essentially the same conformation as that of the dog.

===Radius and Ulna===
*These are complete bones in the ox but are entirely fused
*There is a proximal and distal interosseous space which are the only two places where the shafts are seperated
*The ulna's proximal end is caudal to the radius and it's distal end forms the lateral styloid process, distal to the radius and articulating with the ulnar carpal bone.

==Joints of the Proximal Forelimb==
===Shoulder Joint===

*The joint capsule attaches a very short distance from the periphery of the articular surfaces.
*The '''intertubercular (bicipital) bursa''' lies between the humeral tubercles cushioning the bicipital tendon.
*The bursa and tendon are held in place by the '''transverse humeral retinaculum''' running between the greater and lesser tubercles of the humerus.

===Elbow Joint===

*The joint capsule attaches to the articular surface of the condyle, the periphery of the olecranon fossa and the articular cartilage of the trochlear notch of the ulna. It fuses with the collateral ligaments.
*Paired collateral ligaments attach the epicondyles to the tuberosities of the radius and ulna.

==Structures of the Distal Forelimb==

===Carpal bones===

Carpal bones comprise two rows:
*Proximally, (mediolaterally), radial, intermediate, ulnar and accessory bones
*Distally, 1st is missing, 2 and 3 are fused

===Metacarpal bones===

These are covered in detail in the [[Bovine Phalanges - Anatomy & Physiology|bovine phalanges]] section.

==Joints of the Distal Forelimb==
===Carpal Joint===

The carpal joint is a compound joint composed of:
*The '''antebrachiocarpal joint''' between the radius/ulna and the proximal carpal bones
*The '''middle carpal joint''' between the two rows of carpal bones
*The '''carpometacarpal joint''' between the distal carpal bones and the proximal metacarpals

The joint is a synovial joint, comprised of a common outer fibrous capsule and three inner synovial pouches, one for each joint.
*'''Collateral ligaments''' extend from the radius to the metacarpal bones on the medial and lateral aspect of the carpus.
*The carpal canal houses both the deep digital flexor tendon and the deep branch of the superficial digital flexor.

==Muscles of the Forelimb==
===Extrinsic Musculature===

These muscle are responsible for joining the forelimb to the trunk, forming a synsarcosis rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs as well as stabilize the scapula.

'''''Trapezius''''': Accessory n.
*Origin: mid-dorsal raphe and supraspinous ligament
*Insertion: spine of the scapula
*Body: two parts, cervical and thoracic separated by aponeurosis
*Action: raises scapula against the trunk and swings cranially to advance the limb

'''''Brachiocephalic m.''''': Accessory n.
*Two parts separated by the clavicle where it exists
*Origin: occipital bone, nuchal ligament, mastoid process
*Insertion: deltoid tuberosity and fascia of limb
*Actions:
**advances the limb and extends the shoulder joint when limb is in motion
**draws head and neck ventrally when limb is fixed

'''''Omotransversarius''''': Accessory n.
*Origin: transverse processes of the atlas
*Insertion: acromion and spine of scapula
*Action: advancing the limb
*Innervation

'''''Latissimus dorsi''''': local branch of brachial plexus
*The '''broadest muscle of the back'''
*Origin: thoracolumbar fascia
*Insertion: teres tuberosity of the humerus
*Actions: antagonist to the brachiocephalic m.
**cranial fibers strap scapula to the chest
**retracts free limb and flexes shoulder joint
**draws trunk forward over the fixed limb

'''''Pectoral mm.''''': brachial plexus
*Two superficial parts, cranial and caudal, these aren't very distinct in the ox
**Origin: cranial sternum
**Insertion:
***cranial ('''descending'''): crest of the humerus distal to the deltoid tuberosity
***caudal ('''transverse'''): covers elbow joint to insert on the medial fascia of the forearm
**Action: adduct the forelimb, assist in protraction and retraction
*One deep part ('''pectoralis profundus'''), with cranial and caudal parts
**Origin: ventral sternum and adjacent cartilage
**Insertions:
***cranial (subclavius): supraspinatus m.
***caudal (pectoralis ascendens): lesser tubercle of the humerus
**Actions:
***slinging trunk between forelimbs
***may also retract free limbs
***draw trunk forward when limb is fixed

'''''Serratis ventralis''''': branch of brachial plexus
*Origin: C4 to 10th rib
*Insertion: medial scapula and scapular cartilage
*Action: supporting the weight of the trunk
**reinforced by strong fascia
**cervical portion can retract the limb
**caudal portion can advance the limb

'''''Rhomboids''''': brachial plexus,
*Origin: nuchal ligament
*Insertion: dorsal border and adjacent scapula
*Action: retracting the limb, may also raise limb

===Intrinsic Musculature===
====Muscles of the Shoulder====
These muscles are grouped:
*Lateral:'''Supraspinatus ''' and '''Infraspinatus''', Suprascapular n. of the brachial plexus
**Origin: the fossae of the scapula
**Insertion: both tubercles of the humerus
**Action: brace the shoulder
**Clinical significance: bursa between the tendon of the infraspinatus and lateral tubercle of the humerus can be the site of inflammation
*Medial:
**'''Supscapularis''': Subscapular n. from the brachial plexus
***Origin: Deep surface of the scapula
***Insertion: medial tubercle of the humerus
***Action: braces medial shoulder joint, potential adductor
**'''Coracobrachialis''': Musculocutaneous n. of the brachial plexus
***Origin: medial supraglenoid tubercle
***Insertion: proximal shaft of the humerus
***Action: fixator
*Caudal (Flexors): Axillary n. of the brachial plexus
**'''Deltoids'''
***Origin: caudal border and spine of the scapula, acromion
****Two heads of origin
***Insertion: deltoid tuberosity on the humerus
**'''Teres Major'''
***Origin: dorsal part of the caudal scapula
***Insertion: teres tuberosity midway down humerus
**'''Teres Minor'''
*There are no defined extensors of the shoulder. Those involved (brachiocephalic m., biceps brachii, supraspinatus, and ascending pectorals) have other, more primary roles.

====Muscles of the Elbow====
''Extensors'': Radial n. from the brachial plexus
*'''Triceps brachii''': Three heads,the medial branch is the most developed
**Long head: caudal margin of the scapula
**Lateral, medial, and accessory heads: shaft of the humerus
**Insertion: olecranon, proteced by tricipital bursa against the bone and subcutaneous bursa against the skin
*'''Tensor fasciae antebrachii'''
**Overlies triceps extending from scapula to olecranon

''Flexors'': Musculocutaneous n. from the brachial plexus
*'''Biceps brachii'''
**Origin: supraglenoid tubercle of the scapula
**Insertion: medial tuberosity of proximal radius and adjacent ulna
**Runs through the intertubercular groove of the humerus
*'''Brachialis'''
**Origin: proximocaudal humerus
**Insertion: spirals to insert next to biceps

====Muscles of the Carpal and Digital Joints====
''Extensors'': Radial n. from the brachial plexus
*Craniolateral position on the forearm
*Almost all originate from the lateral epicondyle of the humerus
*'''Extensor carpi radialis''': most medial, inserts on 2nd/3rd metacarpal bone
*'''Ulnaris lateralis''': most lateral, inserts on accessory carpal bone
*'''Extensor carpi obliquus''': aka '''abductor pollicis longus'''
**Origin: cranial radius
**Insertion: most medial metacarpal bone
*Last two may also serve in medial deviation of the foot
*'''Common Digital Extensor'''
**Insertion: extensor process of the distal phalanx of each digit
*'''Lateral Digital Extensor'''
**Insertion: dorsal proximal phalanges
*'''Medial Digital Extensor'''
**Insertion: middle and distal phalanges

''Flexors'': Median or Ulnar n. of the brachial plexus
*Caudal position on the forearm
*Originate from the caudal medial epicondyle of the humerus
*'''Flexor carpi radialis''': most medial, inserts on upper 2nd/3rd metacarpal bone
*'''Flexor carpi ulnaris''': most lateral, inserts on the accessory carpal bone
*'''Superficial Digital Flexor'''
**Inserion: palmar surface of middle phalanges
*'''Deep Digital Flexor'''
**Passes through carpal canal before branching and continues to palmar distal phalanges

''Interosseus muscles''
*This is covered in more detail in the [[Bovine Phalanges - Anatomy & Physiology|bovine phalanges]] section.

==Vasculature of the Forelimb==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''

Arteries of the Forelimb - Anatomy & Physiology

2008-09-08T11:20:11Z

Katherine: /* '''Axillary Artery''' */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>
<big><center>[[Forelimb - Anatomy & Physiology|'''BACK TO FORELIMB''']]</center></big>

'''This page is based around the anatomy of the canine forelimb.'''
'''Essentially the lay out of the arteries is similar in domestic species.'''

Oxygenated blood leaving the heart flows into the aorta, one of it's earliest branches is the '''subclavian artery''' which supplies blood to the forelimb, neck and cervicothoracic junction. It moves round the cranial border of the first rib and enters the limb via the axilla; at this point it changes it's name to the '''axillary artery'''. It is this vessel that supplies the forelimb.

=='''Axillary Artery'''==

It crosses the axillary space and continues distally along the medial aspect of the limb. Below are the branches of the axillary artery.

* '''Axillary a.'''
** External thoracic a. - branches to the thoracic wall
** Lateral thoracic a. - branches to the thoracic wall
** '''Subscapular a.''' - supplies muscles of the shoulder; it runs dorsally on the caudal border of the scapula between the teres major and subscapularis muscles
* '''Brachial a.''' - the axillary a. changes its name to brachial a. at the point of the teres major tuberosity. It runs along the medial aspect of the humerus, then along the craniomedial aspect of the elbow and then along the forearm before changing its name to the median a.
** '''Deep brachial a.''' - supplies the tricipital mass
** '''Collateral ulnar a.''' - supplies the caudal aspect of the forearm
** '''Superficial brachial a.''' - supplies the cranial aspect of the forearm, runs superficially next to the cephalic vein and radial nerve
*** Cranial superficial antebrachial a.
**** Dorsal common digital aa.
** '''Transverse cubital a.''' - branches off at the point of the elbow
** '''Common interosseous a.''' - branches off just distal to the elbow
*** '''Ulnar a.''' - supplies the digital and carpal flexors
*** '''Cranial interosseous a.''' - runs between the interossoeus space to supply the dorsal muscles of the forearm
*** '''Caudal interosseous a.''' - runs to the palmar acrhes of the proximal metacarpus
**** Superficial palmar arch
***** Palmar commo digital aa.
**** Deep palmar arch
***** Palmar metacarpal aa.
* '''Median a.''' - runs on the caudomedial aspect with the median nerve deep to the flexor carpi radialis, passes through the carpal canal and forms branches to connect with the interosseous aa. thus forming the arterial arches of the foot.
** '''Radial a.'''

Canine Forelimb - Anatomy & Physiology

2008-09-08T11:07:28Z

Katherine: /* Scapula */

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==Structures of the Proximal Forelimb and Shoulder==

===[[Forelimb - Anatomy & Physiology#Scapula|Scapula]]===

The Scapula forms the basis of the shoulder region, providing points of attachment of extrinsic and intrinsic muscles. It is held in place by a synsarcosis of muscles and does not form a conventional articulation with the trunk.
*The spine culminates in the '''acromion'''.
*The articular surface of the glenoid cavity and continues round onto the supraglenoid tubercle.
*The scapular cartilage is comprised of only a very narrow rim.

===[[Forelimb - Anatomy & Physiology#Clavicle|Clavicle]]===

In the dog and cat, a remnant of bone may remain embedded in the fibrous intersection in the brachiocephalicus, which may prove misleading in radiographic images.

===[[Forelimb - Anatomy & Physiology#Humerus|Humerus]]===

The Humerus is the long bone of the forearm, articulating with the scapula to form the shoulder and the radius and ulna to form the elbow. In situ, it lies obliquely along the ventral thorax and is more horizontal in larger species.

*The greater tubercle is not seperated into two parts like in other species
*In dogs and cats, it articulates with the radius medially via a trochlea and the ulna laterally via a '''capitulum'''

===[[Forelimb - Anatomy & Physiology#Radius|Radius]]===

*A radial tuberosity provides a site of attachment for brachialis and biceps brachii. This roughened area is very variable in size in dogs and can be non-exsistent.

===[[Forelimb - Anatomy & Physiology#Ulna|Ulna]]===

*The ulna shaft tapers distally, lying oblique to the radius, i.e. the proximal end lies medial and the distal end lateral to the radius.
*There is a distinct gap between it and the radius, which is filled by the pronator quadratus muscle.
*The distal styloid process is blunt and articulates with the ulnar carpal bone, accessory carpal bone and ulnar notch of the radius.

==Joints of the Proximal Forelimb==
===[[Forelimb - Anatomy & Physiology#Shoulder Joint|Shoulder Joint]]===

*The joint capsule barely extends past the areas of articulation, except where it continues distally into the intertubercular groove of the humerus. This provides cushioning and synovial support for the bicipital tendon.
*The bicipital tendon and the joint capsule pouch are held in place by the '''transverse humeral retinaculum''', which lies betwwen the greater and lesser tubercles of the humerus.

===[[Forelimb - Anatomy & Physiology#Elbow Joint|Elbow Joint]]===

*The radius articulates with the capitulum and lateral trochlear surface of the humeral condyle. Whilst the medial part articulates with the trochlear notch of the ulna.
*To allow the radius to rotate slightly the radial head has a marginal band of cartilage making the articular circumference. It faces the radial notch of the ulna bewteen the medial and lateral coronoid processes.
*The joint capsule runs from just proximal to the articular surface of the condyle of the humerus to the periphery of the olecranon fossa; it pouches between the ulna and radius, and under the tendinous attachments of some muscles.
*'''Collateral ligaments''' - are paired and lie medially and laterally; they both proximally attach to the epicondyle and distally attaches to the tuberosities of the radius and ulna.
*'''Annular ligament''' of the radius - attaches to the sides of the coronoid process of the ulna. This runs deep to the collateral ligaments and forms a ring for the radial head to turn in during pronation and supination.
*The radius and ulna are joined mid-shaft by the '''interosseous ligament'''; the remainder is filled by the interosseous membrane.

==Structures of the Distal Forelimb==

===[[Forelimb - Anatomy & Physiology#Carpal bones|Carpal Bones]]===

Carpal bones comprise two rows:
*Proximally - the radial and intermediate bones are fused to form the '''radial''' carpal bone. The accessory carpal bone articulates with both the ulnar carpal bone and the distal ulna.
*Distally - bones I-IV are present

===[[Forelimb - Anatomy & Physiology#Metacarpal bones|Metacarpal Bones]]===

These are covered in detail in the [[Canine Phalanges - Anatomy & Physiology|canine phalanges]] section.

==Joints of the Distal Forelimb==
===[[Forelimb - Anatomy & Physiology#Carpal Joint|Carpal Joint]]===

*The '''synovial membranes''' form three compartments corresponding to each joint. The proximal is the largest whilst the middle carpal and carpometacarpal sacs communicate and extend into the intermetacarpal articulations.
*The fibrous joint capsule is common to all three joints and attaches to the individual bones and various intercarpal ligaments.
*The '''extensor retinaculum''' is fibrous collagenous tissue on the dorsal aspect that allows passage of the extensor tendons.
*On the palmar aspect lies the '''palmar carpal fibrocartilage''' that provides attachment for some metacarpal bones.
*Paired '''collateral ligaments''' bridge the sides of the three main articulations.
*The '''flexor retinaculum''' is the carpal fascia on the palmar aspect and lies between the accessory carpal bone and the medial aspect of the carpus. This with the joint capsule and medial surface of the accesory carpal bone makes up the '''carpal canal'''. It houses just the deep digital flexor tendon in the dog.
*The intermetacarpal joint are tight joints between the proximal ends of the metacarpals. The joint capsules are continuous with that of the carpal joint. They are hold together by interosseous metacarpal ligaments.

==Muscles of the Forelimb==
===[[Forelimb - Anatomy & Physiology#Extrinsic Musculature|Extrinsic Musculature]]===

These muscle are responsible for joining tht forelimb to the trunk, forming a synsarcosis rather than a conventional joint. Collectively, they act to transfer the weight of the body to the forelimbs as well as stabilize the scapula.

'''''Trapezius''''': Accessory n.
*Origin: mid-dorsal raphe and supraspinous ligament
*Insertion: spine of the scapula
*Body: two parts, cervical and thoracic separated by aponeurosis
*Action: raises scapula against the trunk and swings cranially to advance the limb

'''''Brachiocephalic m.''''': Accessory n.
*Two parts separated by the clavicle
*Origin: clavicle
*Insertion: median raphe of the neck and the occipital bone. The ventral part attaches to the mastoid process
*Actions:
**advances the limb and extends the shoulder joint when limb is in motion
**draws head and neck ventrally when limb is fixed

'''''Omotransversarius''''': Accessory n.
*Origin: transverse processes of the atlas
*Insertion: acromion and distal spine of the scapula
*Action: advancing the limb
*Innervation

'''''Latissimus dorsi''''': local branch of brachial plexus
*The '''broadest muscle of the back'''
*Origin: thoracolumbar fascia
*Insertion: teres tuberosity of the humerus
*Actions: antagonist to the brachiocephalic m.
**cranial fibers strap scapula to the chest
**retracts free limb and flexes shoulder joint
**draws trunk forward over the fixed limb

'''''Pectoral mm.''''': brachial plexus
*Two superficial parts, cranial and caudal
**Origin: cranial sternum
**Insertion:
***cranial ('''descending'''): crest of the humerus distal to the deltoid tuberosity
***caudal ('''transverse'''): covers elbow joint to insert on the medial fascia of the forearm
**Action: adduct the forelimb, assist in protraction and retraction
*One deep part ('''pectoralis profundus'''), with cranial and caudal parts
**Origin: ventral sternum and adjacent cartilage
**Insertions:
***cranial (subclavius): supraspinatus m.
***caudal (pectoralis ascendens): lesser tubercle of the humerus
**Actions:
***slinging trunk between forelimbs
***may also retract free limbs
***draw trunk forward when limb is fixed

'''''Serratis ventralis''''': branch of brachial plexus
*Origin: C4 to 10th rib
*Insertion: medial scapula and scapular cartilage
*Action: supporting the weight of the trunk
**reinforced by strong fascia
**cervical portion can retract the limb
**caudal portion can advance the limb

'''''Rhomboids''''': brachial plexus
*Origin: nuchal ligament, 4th - 6th thoracic spine
*Insertion: dorsal border and adjacent scapula
*Action: retracting the limb, may also raise limb

===[[Forelimb - Anatomy & Physiology#Intrinsic Musculature|Intrinsic Musculature]]===
====Muscles of the Shoulder====
These muscles are grouped:
*Lateral:'''Supraspinatus ''' and '''Infraspinatus''', Suprascapular n. of the brachial plexus
**Origin: the fossae of the scapula
**Insertion: both tubercles of the humerus
**Action: brace the shoulder
**Clinical significance: bursa between the tendon of the infraspinatus and lateral tubercle of the humerus can be the site of inflammation
*Medial:
**'''Supscapularis''': Subscapular n. from the brachial plexus
***Origin: Deep surface of the scapula
***Insertion: medial tubercle of the humerus
***Action: braces medial shoulder joint, potential adductor
**'''Coracobrachialis''': Musculocutaneous n. of the brachial plexus
***Origin: medial supraglenoid tubercle
***Insertion: proximal shaft of the humerus
***Action: fixator
*Caudal (Flexors): Axillary n. of the brachial plexus
**'''Deltoids'''
***Origin: acromion, the length of the scapular spine
***Insertion: deltoid tuberosity on the humerus, fascia of the lateral arm
**'''Teres Major'''
***Origin: dorsal part of the caudal scapula
***Insertion: teres tuberosity midway down humerus

====[[Forelimb - Anatomy & Physiology#Muscles of the Elbow|Muscles of the Elbow]]====
''Extensors'': Radial n. from the brachial plexus
*'''Triceps brachii''': Has four heads in the dog
**Long head: caudal margin of the scapula
**Lateral, medial, and accessory heads: shaft of the humerus
**Insertion: olecranon, proteced by tricipital bursa against the bone and subcutaneous bursa against the skin
*'''Tensor fasciae antebrachii'''
**Origin: tendon and lateral surface of the latissimus dorsi

''Flexors'': Musculocutaneous n. from the brachial plexus
*'''Biceps brachii'''
**Origin: supraglenoid tubercle of the scapula
**Insertion: medial tuberosity of proximal radius and adjacent ulna
**Runs through the intertubercular groove of the humerus
*'''Brachialis'''
**Origin: proximocaudal humerus
**Insertion: spirals to insert just proximal to biceps

====[[Forelimb - Anatomy & Physiology#Muscles of Supination and Pronation|Muscles of Supination and Pronation]]====
''Supinators'': Radial n. from the brachial plexus
*'''Brachioradialis'''
**Origin: lateral epicondyle of the humerus
**Insertion: distal part of medial radius
**Often much reduced and sometimes absent
*'''Supinator'''
**Deep to extensor muscles, passing from lateral humeral epicondyles to upper medial radius

''Pronators'': Median n. from the brachial plexus
*'''Pronator teres'''
**Origin: medial epicondyle of the humerus
**Insertion: dorsal surface and medial border of radius
*'''Pronator quadratus'''
**Origin: palmar surface of radius and interosseous ligament
**Insertion: interosseous border of the ulna

====[[Forelimb - Anatomy & Physiology#Muscles of the Carpal and Digital Joints|Muscles of the Carpal and Digital Joints]]====
''Extensors'': Radial n. from the brachial plexus
*Craniolateral position on the forearm
*Almost all originate from the lateral epicondyle of the humerus
*'''Extensor carpi radialis''': most medial, inserts on middle metacarpal bone
*'''Ulnaris lateralis''': most lateral, inserts on accessory carpal bone and 5th metacarpal
*'''Extensor carpi obliquus''': aka '''abductor pollicis longus'''
**Origin: cranial radius
**Insertion: 1st metacarpal
*Last two may also serve in medial deviation of the paw
*'''Common Digital Extensor'''
**Insertion: extensor process of the distal phalanx of each digit
**Sends a medial branch to dew caw
*'''Lateral Digital Extensor'''
**Insertion: dorsal proximal phalanges of 3rd to 5th digit

''Flexors'': Median or Ulnar n. of the brachial plexus
*Caudal position on the forearm
*Originate from the caudal medial epicondyle of the humerus
*'''Flexor carpi radialis''': most medial, inserts on upper 2nd/3rd metacarpal bone
*'''Flexor carpi ulnaris''': most lateral, inserts on the accessory carpal bone
*'''Superficial Digital Flexor'''
**It divides into four branches which insert on the middle phalanges of all digits
*'''Deep Digital Flexor'''
**Passes through carpal canal before branching and continues to palmar distal phalanges

''Interosseus muscles''
*Support metacarpophalnageal joints
*Arise from palmar proximal metacarpal bones and insert on sesamoid bones within the joints, continued by ligaments to phalanges

==Vasculature of the Forelimb==
*'''[[Arteries of the Forelimb - Anatomy & Physiology|Arteries of the Forelimb]]'''
*'''[[Veins of the Forelimb - Anatomy & Physiology|Veins of the Forelimb]]'''
*'''[[Lymphatics of the Forelimb - Anatomy & Physiology|Lymphatics of the Forelimb]]'''

Forelimb - Anatomy & Physiology

2008-09-08T11:04:55Z

Katherine: /* Innervation of the Forelimb */

Forelimb - Anatomy & Physiology

2008-09-08T11:02:10Z

Katherine: /* Muscles of the Carpal and Digital Joints */

Forelimb - Anatomy & Physiology

2008-09-08T10:49:37Z

Katherine: /* Metacarpal bones */

Forelimb - Anatomy & Physiology

2008-09-08T10:46:47Z

Katherine: /* Radius */

Syrinx - Anatomy & Physiology

2008-09-08T09:11:52Z

Katherine: /* Introduction */

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==Introduction==

Vocalisation is an important evolutionary ability of birds. The extent of song varies in different avian species from complex pitches, patterns and rhythms in songbirds to the amusing squawk of penguins. Birds lack vocal folds so sound is produced in the syrinx which is the avian equivalent of the mammalian vocal cords.

[[Image:Syrinx Anatomy.jpg|thumb|right|150px|Anatomy of the Syrinx - Copyright RVC]]

==Structure==

*Specialisation of the trachea bifurcation

*Located at the caudal end of the trachea and at the beginning of the primary bronchi

*Tracheal cartilages of the syrinx are complete and sturdy

*Bronchial cartilages are incomplete

*Paired sternotrachealis muscle pulls the [[Trachea - Anatomy & Physiology|trachea]] towards the syrinx

*Shape and size of syrinx varies between species

*Composed of ossified cartilages, vibrating membranes and muscles

*Surrounded by an air sac

==Function==

*Lateral and medial walls of the primary bronchi are membranous and flutter which produces sound

*Sound is produced on expiration

*Increased pressure in the clavicular air sac causes the tympanic membrane of the syrinx to be forced into the lumen and vibrate

*Tension of the membranes is controlled by the tracheolateral muscles

*Each half of the syrinx can function independently allowing 2 different notes to be produced at the same time
[[Image:Modified Syrinx.jpg|thumb|right|150px]]
==Species Differences==

*Drakes and Cobs (male swans) have an enlarged osseous bulla on the left side of the syrinx which acts as a resonator

*Songbirds have a complex set of syringeal muscles

*Sexual dimorphisms occurs in songbirds, with the males of the species usually producing a more complex birdsong, which directly relates to the size of the area of the brain responsible for song

*Parrots have a thick [[Oral Cavity - Tongue - Anatomy & Physiology|tongue]] which allows them to make sounds similar to humans

*Sound travels from the syrinx and is modified in the throat, [[Oral Cavity - Tongue - Anatomy & Physiology|tongue]] and mouth in parrots

==Links==

[[Syrinx - Musculoskeletal - Flashcards|Syrinx Flashcards]]

Pharynx - Anatomy & Physiology

2008-09-08T09:08:47Z

Katherine: /* Structure and Function */

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==Introduction==
[[Image:Developing Head.jpg|thumb|right|150px|Developing Head - Copyright RVC]]
The pharynx is part of both the [[Cardiorespiratory System - Anatomy & Physiology|respiratory]] and [[Alimentary - Anatomy & Physiology|digestive]] system. Both systems have entrances to the pharynx but they are separated from each other by the [[Soft Palate - Anatomy & Physiology|soft palate]].

During exercise or during respiratory distress, the mouth can be used as an additional opening of the respiratory system and then the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] also becomes an air-way.

The pharynx can be split into different regions- the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]], [[Larynx - Anatomy & Physiology#Laryngeal Pharynx|laryngeal pharynx]] (sometimes referred to as the oesophageal pharynx) and the [[Nasopharynx - Anatomy & Physiology|nasopharynx]]
[[Image:Nasopharynx.jpg|thumb|right|150px|Nasopharynx Anatomy - Copyright RVC]]
==Structure and Function==

*Opening of the [[Larynx - Anatomy & Physiology|larynx]] is on the floor of the pharynx

*Caudal and dorsal to the laryngeal opening is the opening into the [[Oesophagus - Anatomy & Physiology|oesophagus]]

*In the dorsal region of the [[Nasopharynx - Anatomy & Physiology|nasopharynx]] there are paired openings into the Auditory (Eustacian) Tubes

*The lining of the middle ear cavity and auditory tube is continuous with that of the [[Nasopharynx - Anatomy & Physiology|nasopharynx]]

*Located between the base of the skull and the first two cervical vertebrae dorsally

*[[Larynx - Anatomy & Physiology|larynx]] ventrally

*[[Skull and Facial Muscles - Anatomy & Physiology#Mandible (mandibula)|Mandible]], pterygoid muscles and [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]] laterally

*Walls contain striated muscle
[[Image:Pharynx Anatomy.jpg|thumb|right|150px|Pharynx Labelled - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
*During [[Deglutition|swallowing]] the [[Soft Palate - Anatomy & Physiology|soft palate]] is raised which divides the pharynx into dorsal and ventral sections
**Laterally, two pairs of palatopharyngeal arches are present from the [[Soft Palate - Anatomy & Physiology|soft palate]] to the [[Oesophagus - Anatomy & Physiology|oesophagus]]
**The dorsal compartment is the [[Nasopharynx - Anatomy & Physiology|nasopharynx]]
**The rostral compartment is the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]]

*The [[Larynx - Anatomy & Physiology#Laryngeal Pharynx|laryngeal pharynx]] is separated from the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] by the [[Epiglottis|epiglottis]]

*[[Tonsils - Anatomy & Physiology|Tonsils]] are present on the lateral walls of the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]]
**Covered by flaps of mucosa
**Partially visible in the open mouth

*The pharynx plays an important role in [[Deglutition|deglutition]]
[[Image:Soft Palate Separating Pharyngeal Cavities.jpg|thumb|right|150x|Soft palate dividing the oropharynx and the nasopharynx - Copyright RVC]]

==Musculature==

===Muscles that constrict===

*Run dorsally to roof of pharynx

*Rostral constrictor muscles are the '''hyopharyngeous''', '''pterygopharyngeous''' and the '''palatopharyngeous muscles'''
**Originate from the [[Tonsils - Anatomy & Physiology#Pterygoid Bone (os pterygoideum)|pterygoid]] region of the skull and the aponeurosis of the [[Soft Palate - Anatomy & Physiology|soft palate]]
**Shorten the pharynx

*Middle constictor muscle is the '''thyopharyngeous muscle'''
**Origniates from the [[Hyoid Apparatus - Anatomy & Physiology|hyoid bone]]

*Caudal constictor muscles are the '''cricopharyngeous muscle'''
**Originates from the [[Larynx - Anatomy & Physiology#Thyroid Cartilage|thyroid cartilage]] of the [[Larynx - Anatomy & Physiology|larynx]]

===Muscles that dilate===

*Enclose pharynx laterally and dorsally

*Dilator muscle is the '''stylopharyngeous muscle'''

*Originates from the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]

*Widens the rostral pharynx

===Muscles that shorten===

*The '''pterygopharyngeous muscle''' shortens the pharynx

*Enclose pharynx laterally and dorsally

===Muscles that close the Pharyngeal Arch===

*The '''palatopharyngeous muscle''' also closes the pharyngeal arch

==Innervation==

*Pharyngeal muscles arise from arch 4

*Pharyngeal branch of the vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) from the cranial root of the accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])

*Stylopharyngeous muscle comes from arch 3 and is innervated by the accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
*Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]) supplies taste to the pharynx
[[Image:Pharyngeal Tonsil.jpg|thumb|right|150px|Histology of Pharyngeal Tonsil - Copyright RVC]]
==Histology==

*Fibroelastic aponeurosis supports the mucosa

*[[Nasopharynx - Anatomy & Physiology|nasopharynx]] has pseudostratified columnar epithelium

*[[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] and the [[Larynx - Anatomy & Physiology#Laryngeal Pharynx|laryngeal pharynx]] have stratified squamous epithelium

*[[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] and the [[Larynx - Anatomy & Physiology#Laryngeal Pharynx|laryngeal pharynx]] have [[Oral Cavity - Salivary Glands - Anatomy & Physiology|salivary glands]] present
[[Image:Pharynx Anatomy.jpg|thumb|right|150px|Palatine Tonsil - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
==Species Differences==

====Canine====
*Single duct connects [[Nasopharynx - Anatomy & Physiology|nasopharynx]] to the [[Nasal cavity - Anatomy & Physiology|nasal cavity]]

*[[Tonsils - Anatomy & Physiology|Tonsils]] are a compact mass which point away from the lumen of the pharynx

====Equine====
*Auditory tube opens into the [[Special Senses - Auditory - Anatomy & Physiology#Equine Gutteral Pouch|gutteral pouch]]

*[[Tonsils - Anatomy & Physiology|Tonsils]] are diffuse and raised slightly

====Ruminants====
*[[Tonsils - Anatomy & Physiology|Tonsils]] are a compact mass which point towards the lumen of the pharynx

==Links==

[[Oral Cavity - Oropharynx - Anatomy & Physiology|Oropharynx - Anatomy & Physiology]]

[[Nasopharynx - Anatomy & Physiology]]

[[Larynx - Anatomy & Physiology#Laryngeal Pharynx|laryngeal pharynx]]

[[Pharynx - Musculoskeletal - Flashcards|Pharynx Flashcards]]

Skull and Facial Muscles - Anatomy & Physiology

2008-09-03T13:26:22Z

Katherine: /* Mandible (mandibula) */

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==Introduction==
[[Image:Deer Skull with Antlers.jpg|thumb|right|150px|Deer Skull - Copyright nabrown RVC]]
The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]], mandible, ossicles of the middle [[Special Senses - Auditory - Anatomy & Physiology|ear]] and the cartilage of the [[Larynx - Anatomy & Physiology|larynx]], nose and [[Special Senses - Auditory - Anatomy & Physiology|ear]]. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in [[Horn - Anatomy & Physiology|horned]] ungulates such as red deer stags.

The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.

The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|intramembranous ossification]].

The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|endochondral and intramembranous ossification]].

The various facial muscles attach onto the skull in different places depending on their function. Movement of the external apendages, [[Mastication|mastication]] and facial expressions all rely on the movement of the facial muscles.

==Structure==

*The skull is made of many smaller bones

*Most of the skull bones are paired

*Cartilage or fibrous tissue separates the bones of the skull in the young animal

*Once growth has ceased, the sutures begin to ossify

==Function==

*Protection of brain

*Support facial muscles by providing origin and insertion sites

*Foramen provide entry and exit places for the vasculature and nervous system

*Defense

==Bones of the Skull==
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===Occipital Bone (os occipitale)===

*Forms the nuchal wall

*Forms the foramen magnum

*Basilar part (pars basilaris)
**Caudal base of the cranium
**Rostral to foramen magnum
**Joined by cartilagenous suture to basisphenoid bone
**Muscular tubercules on ventral surface where the flexors of the head and neck attach
**Caudal cranial fossa enclose the pons and medulla oblongata

*Squamous part (pars squamosa)
**Dorsal to lateral parts and occipital condyles
**Nuchal crest present
***Easily palpable
***Landmark for collection of cerebrospinal fluid (CSF)
**External occipital protuberances present which provide muscle attachment sites for the nuchal ligament

*Lateral parts (partes laterales)
**Lateral borders of foramen magnum
**Occipital condyles present which articulate with the atlas to form the atlanto-occipital joint
**Paracondylar process present which provides muscle attachment sights for muscles of the head
**Hypoglossal canal

===Sphenoid Bone (os sphenoidale)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
*Forms the base of the neurocranium

*Composed of a body and wings

*Bones separated by cartilage which ossifies with age

*Presphenoid (os praespenoidale)
**Rostrally
**Rostral caudal fossa
**Hollow body with sphenoid sinuses located inside
**Sphenoid rostrum present
**Optic chiasma
**Optic canal

*Basisphenoid (os basispenoidalis)
**Caudally
**Median cranial fossa
**The wings oppose the temporal bone, maxilla, orbit and the brain
**Wings form the oval foramen and other foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) carotid notch, oval foramen and spinous notch (in the horse)
**Pterygoid processes present
**Alar canal (rostral and caudal alar foramen)

===Temporal Bone (os temporale)===

*Composed of squamous, petrosal and tympanic parts

*Lateral wall of the cranial cavity

*Articulates with the frontal, pareital and sphenoid bones
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
*Zygomatic process
**On squamous part
**Joins the temporal process of the zygomatic bone to form the zygomatic arch
**Forms the articulating surface of the [[Mastication#Jaw Articulation|temporomandibular joint]]

*Articular tubercle present

*Mandibular fossa present

*Occipital process and retrotympanic process surrounds the external acoustic meatus

*Petrosal part encloses the inner ear
**Internal acoustic meatus present
**Forms mastoid process ventrally
**Styloid process present which attaches the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]
**Stylomastoid foramen present

*Tympanic part is the ventral section of the temporal bone
**Tympanic bulla present
**Tympanic membrane separates tympanic cavity from external acoustic meatus
**Encloses auditory ossicle dorsally
**Musculotubal canal where tensors of the [[Soft Palate - Anatomy & Physiology#Musculature and Innervation|soft palate]] originate

===Frontal Bone (os frontale)===

*Paired

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section
**Forms the zygomatic process laterally
**Forms the dorsal part of the orbit
**Lacrimal gland present
**Temporal line present which extends into the external sagittal crest
**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen
**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle
[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

===Parietal Bone (os parietale)===

*Paired

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone
**Fuses with age

===Ethmoid Bone (os ethmoidale)===
[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]
*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

*The ethmoid bone is separated from the cranial cavity by the cribiform plate
**Numerous small foramina where the olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes
**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses
**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates
**The first endoturbinate forms the dorsal nasal conchae
**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses
**Dorsal nasal meatus
**Middle nasal meatus
**Ventral nasal meatus

===Nasal Bone (os nasale)===
[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]
*Paired

*Forms the roof of the nasal cavity

*Dorsal nasal conchae attach to the ethmoidal crest on the internal surface

*Rostral suture form the apex

*Between the nasal and incisive bones is the nasoincisive notch

===Lacrimal Bone (os lacrimale)===

*Forms part of the lateral wall of the face and orbit

*Situated near the medial canthus

*It articulates with the frontal bone, zygomatic bone and maxilla
**Also articulates with the nasal bone in ruminants and the horse
**Also articulates with the palatine bone in carnivores

*Composed of an orbital and facial part separated by supra- and infraorbital margins

*The nasolacrimal duct is present by the margin of the orbital surface

*Ventral oblique muscle attaches caudal to the margin of the orbital surface

*Nasal surface forms the boundaries of the maxillary and frontal sinuses

===Zygomatic Bone (os zygomaticum)===

*Lateral and ventral to the lacrimal bone

*Forms the orbit and zygomatic arch

*Supraorbital margin formed by the zygomatic process of the temporal bone and the frontal process of the zygomatic bone

*Facial crest present on lateral surface
[[Image:Cow skull lateral view.jpg|thumb|right|150px|Cow skull (incisive bone, nasal bone, maxilla, nasoincisive notch labelled) - Copyright nabrown RVC]]

===Incisive Bone (os incisivium)===

*Paired

*Composed of body, nasal, palatine and alveolar parts

*Joins with the maxilla to form the interalveolar margin

*Forms the rostral part of the facial section of the skull, the roof of the [[Hard Palate - Anatomy & Physiology|hard palate]] and the opening to the nasal cavity

*The alveolar process form conical sockets for the incisor teeth

===Palatine Bone (os palatinum)===

*Paired

*Between the maxilla, sphenoid and pterygoid bones

*Composed of a horizontal plate (forms part of the [[Hard Palate - Anatomy & Physiology|hard palate]]), perpendicular plate (forms the dorsal and lateral walls of the nasopharyngeal meatus) and the choanae

*Nasal crest present on the horizontal plate

*Palatine sinus present on horizontal plate
[[Image:Palatine Bone.jpg|thumb|right|150px|Palatine Bone and Maxilla (Pig) - Copyright nabrown RVC]]

===Vomer===

*Unpaired

*Extends from the choanae of the palatine bone to the floor of the nasal cavity

*Attaches to the median nuchal crest

*Septal sulcus formed which surrounds nasal cavity

===Pterygoid Bone (os pterygoideum)===

*Paired

*Bordered by the palatine and sphenoid bones

*Forms dorsal and lateral walls of the nasopharyngeal cavity

*Pterygoid hamulus present

===Maxilla===
[[Image:Horse Maxilla.jpg|thumb|right|150px|Horse Maxilla - Copyright RVC]]
*Forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Hard Palate - Anatomy & Physiology|hard palate]]

*Forms the ventral nasal conchae

*It articulates with all of the facial bones as it is the largest bone of the face

*The maxillary body encloses the maxillary sinuses and forms the external surface of the face
**Facial crest present

*Infraorbital foramen palpable

*Conchal crest on nasal surface where the ventral nasal conchae attaches

*Lacrimal canal opens into the lacrimal foramen on the nasal surface

*Pterygopalatine surfaces are the caudal part of the maxilla which terminate in the maxillary tubercle where the sphenopalatine, maxillary and caudal palatine foramen are present

*Alveolar processes present separated by interalveolar septa

*Palatine process forms the [[Hard Palate - Anatomy & Physiology|hard palate]] with the palatine bone

*Palatine fissure formed at the articulation with the incisive bone

*Nasal surface of palatine process forms the nasal crest and encloses part of the palatine sinuses

*Oral surface has numerous palatine foramina present
[[Image:Cow Mandible.jpg|thumb|right|150px|Mandible of the Cow in situ - Copyright nabrown RVC]]

===Mandible (mandibula)===

*The manidble can be divided into the body and the ramus

*The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally)
**The section of the body which does not support any teeth is called the interalveolar margin or diastema
**Mandibular canal present
**Mental foramen present
**Facial notch on ventral surface where the parotid duct (in herbivores) and facial vessels run
[[Image:Parrot Mandible.jpg|thumb|right|150px|Mandible of the Parrot - Copyright nabrown RVC]]
*The ramus extend from the caudal end of the body dorsally towards the zygomatic arch
**The masseter muscle attaches to the lateral surface at the masseteric fossa
**The medial pterygoid attaches to the medial surface at the pterygoid fossa
**The angle of the mandible terminates dorsally in the condylar process and the coronoid process which are separated by the mandibular notch
**The temporal muscle inserts onto the coronoid head
**The condylar process articulates with the mandibular process of the skull (see [[Mastication#Jaw Articulation|here]])

==Major Foramen and Canals==

*Jugular Foramen
**Located either side of basilar part of occipital bone
**Adjacent to tympanic bulla
**Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]), vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) and accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
**Internal carotid artery
[[Image:Foramen Magnum.jpg|thumb|right|150px|Foramen Magnum (Horse) - Copyright nabrown RVC]]
*Foramen Magnum
**Formed by occipital bones
**Spinal cord's passage to the neck and body
**Alar ligaments run through
**Vertebral arteries run through
**Spinal arteries run through
**Tectoral membranes run through

*Hypoglossal Canal
**Between paracondylar and condylar processes on lateral part of occipital bone
**Hypoglossal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XII]])
**Condylar artery and vein

*Optic Chiasma
**Runs in transverse depression behind sphenoid rostrum on presphenoid bone
**Path of the optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])
[[Image:Sheep Skull Eye Foramen.jpg|thumb|right|150px|Skull of a Sheep (optic canal, ethmoidal foramen and supraorbital foramen labelled) - Copyright nabrown RVC]]
*Optic Canal
**Ends from optic chiasma over wings of the presphenoid bones
**Optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])

*Oval Foramen
**Caudal wing of the basisphenoid bones
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])

*Alar Canal
**Rostral border of the basisphenoid bone at the base of the pterygoid processes
**Composed of the caudal alar foramen, rostral alar foramen and the small alar foramen
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Temporal artery
[[Image:Pig Foramen Ventral.jpg|thumb|right|150px|Foramen of the Pig (includes jugular, stylomastoid and lacernum - Copyright nabrown RVC]]
*Stylomastoid Foramen
**Situated on the petrosal part of the temporal bone
**Facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])

*Ethmoidal Foramen
**Perforate the orbital part of the frontal bone
**Olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]])
**Ethmoidal artery and vein
[[Image:Cow Skull dorsal view.jpg|thumb|right|150px|Cow skull (supraorbital foramen, temporal line, supramastoid crest and supraorbital groove labelled) - Copyright nabrown RVC]]
*Orbital Fissure
**On the presphenoid bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]]), occulomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and the abducens nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])

*Supraorbital Foramen
**On the frontal bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]])
**Frontal artery and vein

*Infraorbital Foramen
**On the maxilla
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Infraorbital artery and vein
[[Image:Mental and Infraorbital Foramen.jpg|thumb|right|150px|Mental and Infraorbital foramen (dog) - Copyright nabrown RVC]]
*Mental Foramen
**On rostral end of the mandible
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])
**Mental artery and vein

*Palatine Canal
**Runs through horizontal plate of palatine bone
**Palatine artery
**Palatine vein
**Palatine nerves

*Internal Acoustic Meatus
**Medial surface of the petrosal part of the temporal bone
**Facial opening for the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])
**Cochlear opening, dorsal vestibule opening and the ventral vestibule opening for the vestibulocochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VIII]])

==Facial Muscles==
[[Image:Muscles of Mastication.jpg|thumb|right|150px|Muscle of Mastication (dog) - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
The major facial muscles are covered in the following sections of anatomy and physiology:

[[Oral Cavity - Tongue - Anatomy & Physiology#Muscles|Muscles of the Tongue]]

[[Cheeks - Anatomy & Physiology|Muscles of the Cheeks]]

[[Larynx - Anatomy & Physiology#Intrinsic Musculature|Muscles of the Larynx]]

[[Pharynx - Anatomy & Physiology#Musculature|Muscles of the Pharynx]]

[[Special Senses - Visual - Anatomy & Physiology#Around the Eye|Muscles of the Eye]]

[[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|Muscles of the Ear]]

[[Deglutition|Muscles involved in Deglutition]]

[[Mastication|Muscles of Mastication]]

==Species Differences==
[[Image:Pug skull.jpg|thumb|right|150px|Brachycephalic skull (Pug) - Copyright nabrown RVC]]
===Canine===
*Dogs have different skull lengths depending on breed
**Mesocephalic dogs have average conformation
**Dolichocephalic dogs have longer skull lengths
**Brachycephalic dogs have shorter skull lengths

*2 halves of the mandible do not fuse allowing some movement

*External sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament
[[Image:Lion skull.jpg|thumb|right|150px|Feline skull (Lion) - Copyright nabrown RVC]]
===Feline===
*The mandible appears globular in shape

*Large orbits with complete bony margins

*Large tympanic bulla which can be palpated

*2 halves of the mandible do not fuse allowing some movement

*Weak external sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament which is ossified

*Interpareital bone does not fuse entirely in the adult
[[Image:Horse Skull.jpg|thumb|right|150px|Horse Skull - Copyright nabrown RVC]]

===Equine===

*Weak external sagittal crest arises from nuchal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Long skull length

*Orbit placed more laterally with a complete bony rim

*Strong zygomatic arch which continues on to form the facial crest

*Deep nasoincisive notch

*Prominent hamular process

*Large mandible
**Vascular notch on mandible
**High ramus

*Wings of the basisphenoid bones form the oval foramen, spinous notch and carotid notch

*Foramen lacernum present

*Zygomatic process articulates with the zygomatic process of the temporal bone

*Three rows of ethmoturbinates present
[[Image:Sheep skull.jpg|thumb|right|150px|Sheep skull - Copyright nabrown RVC]]
===Ruminant===
*Skull is short and wide

*[[Horn - Anatomy & Physiology|Cornual]] process on frontal bone

*Nuchal crest reduced to nuchal line

*Prominent temporal line

*Elevated orbital ring which is complete

*No facial crest

*Prominent tympanic bullae

*Nasoincisive notch present

*Wings of the basisphenoid bones form the oval foramen

*No foramen lacernum

*Petrosal and tympanic parts of the temporal bone fused to the squamous part

*Zygomatic process articulates with the frontal process of the zygomatic bone
[[Image:Pig skull.jpg|thumb|right|150px|Pig skull showing tusks - Copyright nabrown RVC]]
===Porcine===
*Thick nucal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Prominent temporal line

*Orbit is incomplete and small

*Strong and deep zygomatic arch

*Large tympanic bullae

*High caudal part of the skull

*Styloid process absent
[[Image:Bird skull.jpg|thumb|right|150px|Bird skull - Copyright nabrown RVC]]
===Avian===
*Pneumatised skull bones
**Spaces in skull bones which connect to airways in the head rather than the air sacs

*Large orbits

*Skull plates are separated by spongy bone

*A single occipital condyle articulates with the atlas allowing more rotation of the head

*In parrots, the nasal bone and frontal bone are joined by a flexible cartliage structure allowing greater jaw opening which is called the craniofacial hinge. This allows kinesis to occur.

*Thin jugal arch (equivalent to zygomatic arch)

*Middle ear contains only the columella (equivalent to the stapes)

==Links==

[[The Skull - Musculoskeletal - Flashcards|Skull Flashcards]]

[[Facial Muscles - Musculoskeletal - Flashcards|Facial Muscles Flashcards]]

Skull and Facial Muscles - Anatomy & Physiology

2008-09-03T13:25:00Z

Katherine: /* Maxilla */

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==Introduction==
[[Image:Deer Skull with Antlers.jpg|thumb|right|150px|Deer Skull - Copyright nabrown RVC]]
The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]], mandible, ossicles of the middle [[Special Senses - Auditory - Anatomy & Physiology|ear]] and the cartilage of the [[Larynx - Anatomy & Physiology|larynx]], nose and [[Special Senses - Auditory - Anatomy & Physiology|ear]]. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in [[Horn - Anatomy & Physiology|horned]] ungulates such as red deer stags.

The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.

The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|intramembranous ossification]].

The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|endochondral and intramembranous ossification]].

The various facial muscles attach onto the skull in different places depending on their function. Movement of the external apendages, [[Mastication|mastication]] and facial expressions all rely on the movement of the facial muscles.

==Structure==

*The skull is made of many smaller bones

*Most of the skull bones are paired

*Cartilage or fibrous tissue separates the bones of the skull in the young animal

*Once growth has ceased, the sutures begin to ossify

==Function==

*Protection of brain

*Support facial muscles by providing origin and insertion sites

*Foramen provide entry and exit places for the vasculature and nervous system

*Defense

==Bones of the Skull==
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===Occipital Bone (os occipitale)===

*Forms the nuchal wall

*Forms the foramen magnum

*Basilar part (pars basilaris)
**Caudal base of the cranium
**Rostral to foramen magnum
**Joined by cartilagenous suture to basisphenoid bone
**Muscular tubercules on ventral surface where the flexors of the head and neck attach
**Caudal cranial fossa enclose the pons and medulla oblongata

*Squamous part (pars squamosa)
**Dorsal to lateral parts and occipital condyles
**Nuchal crest present
***Easily palpable
***Landmark for collection of cerebrospinal fluid (CSF)
**External occipital protuberances present which provide muscle attachment sites for the nuchal ligament

*Lateral parts (partes laterales)
**Lateral borders of foramen magnum
**Occipital condyles present which articulate with the atlas to form the atlanto-occipital joint
**Paracondylar process present which provides muscle attachment sights for muscles of the head
**Hypoglossal canal

===Sphenoid Bone (os sphenoidale)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
*Forms the base of the neurocranium

*Composed of a body and wings

*Bones separated by cartilage which ossifies with age

*Presphenoid (os praespenoidale)
**Rostrally
**Rostral caudal fossa
**Hollow body with sphenoid sinuses located inside
**Sphenoid rostrum present
**Optic chiasma
**Optic canal

*Basisphenoid (os basispenoidalis)
**Caudally
**Median cranial fossa
**The wings oppose the temporal bone, maxilla, orbit and the brain
**Wings form the oval foramen and other foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) carotid notch, oval foramen and spinous notch (in the horse)
**Pterygoid processes present
**Alar canal (rostral and caudal alar foramen)

===Temporal Bone (os temporale)===

*Composed of squamous, petrosal and tympanic parts

*Lateral wall of the cranial cavity

*Articulates with the frontal, pareital and sphenoid bones
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
*Zygomatic process
**On squamous part
**Joins the temporal process of the zygomatic bone to form the zygomatic arch
**Forms the articulating surface of the [[Mastication#Jaw Articulation|temporomandibular joint]]

*Articular tubercle present

*Mandibular fossa present

*Occipital process and retrotympanic process surrounds the external acoustic meatus

*Petrosal part encloses the inner ear
**Internal acoustic meatus present
**Forms mastoid process ventrally
**Styloid process present which attaches the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]
**Stylomastoid foramen present

*Tympanic part is the ventral section of the temporal bone
**Tympanic bulla present
**Tympanic membrane separates tympanic cavity from external acoustic meatus
**Encloses auditory ossicle dorsally
**Musculotubal canal where tensors of the [[Soft Palate - Anatomy & Physiology#Musculature and Innervation|soft palate]] originate

===Frontal Bone (os frontale)===

*Paired

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section
**Forms the zygomatic process laterally
**Forms the dorsal part of the orbit
**Lacrimal gland present
**Temporal line present which extends into the external sagittal crest
**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen
**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle
[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

===Parietal Bone (os parietale)===

*Paired

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone
**Fuses with age

===Ethmoid Bone (os ethmoidale)===
[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]
*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

*The ethmoid bone is separated from the cranial cavity by the cribiform plate
**Numerous small foramina where the olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes
**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses
**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates
**The first endoturbinate forms the dorsal nasal conchae
**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses
**Dorsal nasal meatus
**Middle nasal meatus
**Ventral nasal meatus

===Nasal Bone (os nasale)===
[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]
*Paired

*Forms the roof of the nasal cavity

*Dorsal nasal conchae attach to the ethmoidal crest on the internal surface

*Rostral suture form the apex

*Between the nasal and incisive bones is the nasoincisive notch

===Lacrimal Bone (os lacrimale)===

*Forms part of the lateral wall of the face and orbit

*Situated near the medial canthus

*It articulates with the frontal bone, zygomatic bone and maxilla
**Also articulates with the nasal bone in ruminants and the horse
**Also articulates with the palatine bone in carnivores

*Composed of an orbital and facial part separated by supra- and infraorbital margins

*The nasolacrimal duct is present by the margin of the orbital surface

*Ventral oblique muscle attaches caudal to the margin of the orbital surface

*Nasal surface forms the boundaries of the maxillary and frontal sinuses

===Zygomatic Bone (os zygomaticum)===

*Lateral and ventral to the lacrimal bone

*Forms the orbit and zygomatic arch

*Supraorbital margin formed by the zygomatic process of the temporal bone and the frontal process of the zygomatic bone

*Facial crest present on lateral surface
[[Image:Cow skull lateral view.jpg|thumb|right|150px|Cow skull (incisive bone, nasal bone, maxilla, nasoincisive notch labelled) - Copyright nabrown RVC]]

===Incisive Bone (os incisivium)===

*Paired

*Composed of body, nasal, palatine and alveolar parts

*Joins with the maxilla to form the interalveolar margin

*Forms the rostral part of the facial section of the skull, the roof of the [[Hard Palate - Anatomy & Physiology|hard palate]] and the opening to the nasal cavity

*The alveolar process form conical sockets for the incisor teeth

===Palatine Bone (os palatinum)===

*Paired

*Between the maxilla, sphenoid and pterygoid bones

*Composed of a horizontal plate (forms part of the [[Hard Palate - Anatomy & Physiology|hard palate]]), perpendicular plate (forms the dorsal and lateral walls of the nasopharyngeal meatus) and the choanae

*Nasal crest present on the horizontal plate

*Palatine sinus present on horizontal plate
[[Image:Palatine Bone.jpg|thumb|right|150px|Palatine Bone and Maxilla (Pig) - Copyright nabrown RVC]]

===Vomer===

*Unpaired

*Extends from the choanae of the palatine bone to the floor of the nasal cavity

*Attaches to the median nuchal crest

*Septal sulcus formed which surrounds nasal cavity

===Pterygoid Bone (os pterygoideum)===

*Paired

*Bordered by the palatine and sphenoid bones

*Forms dorsal and lateral walls of the nasopharyngeal cavity

*Pterygoid hamulus present

===Maxilla===
[[Image:Horse Maxilla.jpg|thumb|right|150px|Horse Maxilla - Copyright RVC]]
*Forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Hard Palate - Anatomy & Physiology|hard palate]]

*Forms the ventral nasal conchae

*It articulates with all of the facial bones as it is the largest bone of the face

*The maxillary body encloses the maxillary sinuses and forms the external surface of the face
**Facial crest present

*Infraorbital foramen palpable

*Conchal crest on nasal surface where the ventral nasal conchae attaches

*Lacrimal canal opens into the lacrimal foramen on the nasal surface

*Pterygopalatine surfaces are the caudal part of the maxilla which terminate in the maxillary tubercle where the sphenopalatine, maxillary and caudal palatine foramen are present

*Alveolar processes present separated by interalveolar septa

*Palatine process forms the [[Hard Palate - Anatomy & Physiology|hard palate]] with the palatine bone

*Palatine fissure formed at the articulation with the incisive bone

*Nasal surface of palatine process forms the nasal crest and encloses part of the palatine sinuses

*Oral surface has numerous palatine foramina present
[[Image:Cow Mandible.jpg|thumb|right|150px|Mandible of the Cow in situ - Copyright nabrown RVC]]

===Mandible (mandibula)===

*The manidble can be divided into the body and the ramus

*The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally)
**The section of the body which does not support any teeth is called the interalveolar margin or diastema
**Mandibular canal present
**Mental foramen present
**Facial notch on ventral surface where the parotid duct (in herbivores) and facial vessels run
[[Image:Parrot Mandible.jpg|thumb|right|150px|Mandible of the Parrot - Copyright nabrown RVC]]
*The ramus extend from the caudal end of the body dorsally towards the zygomatic arch
**The masseter muscle attaches to the lateral surface at the masseteric fossa
**The medial pterygoid attaches to teh medial surface at the pterygoid fossa
**The angle of the mandible terminates dorsally in the condylar process and the coronoid process which are separated by the mandibular notch
**The temporal muscle inserts onto the coronoid head
**The condylar process articulates with the mandibular process of the skull (see [[Mastication#Jaw Articulation|here]])

==Major Foramen and Canals==

*Jugular Foramen
**Located either side of basilar part of occipital bone
**Adjacent to tympanic bulla
**Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]), vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) and accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
**Internal carotid artery
[[Image:Foramen Magnum.jpg|thumb|right|150px|Foramen Magnum (Horse) - Copyright nabrown RVC]]
*Foramen Magnum
**Formed by occipital bones
**Spinal cord's passage to the neck and body
**Alar ligaments run through
**Vertebral arteries run through
**Spinal arteries run through
**Tectoral membranes run through

*Hypoglossal Canal
**Between paracondylar and condylar processes on lateral part of occipital bone
**Hypoglossal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XII]])
**Condylar artery and vein

*Optic Chiasma
**Runs in transverse depression behind sphenoid rostrum on presphenoid bone
**Path of the optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])
[[Image:Sheep Skull Eye Foramen.jpg|thumb|right|150px|Skull of a Sheep (optic canal, ethmoidal foramen and supraorbital foramen labelled) - Copyright nabrown RVC]]
*Optic Canal
**Ends from optic chiasma over wings of the presphenoid bones
**Optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])

*Oval Foramen
**Caudal wing of the basisphenoid bones
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])

*Alar Canal
**Rostral border of the basisphenoid bone at the base of the pterygoid processes
**Composed of the caudal alar foramen, rostral alar foramen and the small alar foramen
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Temporal artery
[[Image:Pig Foramen Ventral.jpg|thumb|right|150px|Foramen of the Pig (includes jugular, stylomastoid and lacernum - Copyright nabrown RVC]]
*Stylomastoid Foramen
**Situated on the petrosal part of the temporal bone
**Facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])

*Ethmoidal Foramen
**Perforate the orbital part of the frontal bone
**Olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]])
**Ethmoidal artery and vein
[[Image:Cow Skull dorsal view.jpg|thumb|right|150px|Cow skull (supraorbital foramen, temporal line, supramastoid crest and supraorbital groove labelled) - Copyright nabrown RVC]]
*Orbital Fissure
**On the presphenoid bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]]), occulomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and the abducens nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])

*Supraorbital Foramen
**On the frontal bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]])
**Frontal artery and vein

*Infraorbital Foramen
**On the maxilla
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Infraorbital artery and vein
[[Image:Mental and Infraorbital Foramen.jpg|thumb|right|150px|Mental and Infraorbital foramen (dog) - Copyright nabrown RVC]]
*Mental Foramen
**On rostral end of the mandible
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])
**Mental artery and vein

*Palatine Canal
**Runs through horizontal plate of palatine bone
**Palatine artery
**Palatine vein
**Palatine nerves

*Internal Acoustic Meatus
**Medial surface of the petrosal part of the temporal bone
**Facial opening for the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])
**Cochlear opening, dorsal vestibule opening and the ventral vestibule opening for the vestibulocochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VIII]])

==Facial Muscles==
[[Image:Muscles of Mastication.jpg|thumb|right|150px|Muscle of Mastication (dog) - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
The major facial muscles are covered in the following sections of anatomy and physiology:

[[Oral Cavity - Tongue - Anatomy & Physiology#Muscles|Muscles of the Tongue]]

[[Cheeks - Anatomy & Physiology|Muscles of the Cheeks]]

[[Larynx - Anatomy & Physiology#Intrinsic Musculature|Muscles of the Larynx]]

[[Pharynx - Anatomy & Physiology#Musculature|Muscles of the Pharynx]]

[[Special Senses - Visual - Anatomy & Physiology#Around the Eye|Muscles of the Eye]]

[[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|Muscles of the Ear]]

[[Deglutition|Muscles involved in Deglutition]]

[[Mastication|Muscles of Mastication]]

==Species Differences==
[[Image:Pug skull.jpg|thumb|right|150px|Brachycephalic skull (Pug) - Copyright nabrown RVC]]
===Canine===
*Dogs have different skull lengths depending on breed
**Mesocephalic dogs have average conformation
**Dolichocephalic dogs have longer skull lengths
**Brachycephalic dogs have shorter skull lengths

*2 halves of the mandible do not fuse allowing some movement

*External sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament
[[Image:Lion skull.jpg|thumb|right|150px|Feline skull (Lion) - Copyright nabrown RVC]]
===Feline===
*The mandible appears globular in shape

*Large orbits with complete bony margins

*Large tympanic bulla which can be palpated

*2 halves of the mandible do not fuse allowing some movement

*Weak external sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament which is ossified

*Interpareital bone does not fuse entirely in the adult
[[Image:Horse Skull.jpg|thumb|right|150px|Horse Skull - Copyright nabrown RVC]]

===Equine===

*Weak external sagittal crest arises from nuchal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Long skull length

*Orbit placed more laterally with a complete bony rim

*Strong zygomatic arch which continues on to form the facial crest

*Deep nasoincisive notch

*Prominent hamular process

*Large mandible
**Vascular notch on mandible
**High ramus

*Wings of the basisphenoid bones form the oval foramen, spinous notch and carotid notch

*Foramen lacernum present

*Zygomatic process articulates with the zygomatic process of the temporal bone

*Three rows of ethmoturbinates present
[[Image:Sheep skull.jpg|thumb|right|150px|Sheep skull - Copyright nabrown RVC]]
===Ruminant===
*Skull is short and wide

*[[Horn - Anatomy & Physiology|Cornual]] process on frontal bone

*Nuchal crest reduced to nuchal line

*Prominent temporal line

*Elevated orbital ring which is complete

*No facial crest

*Prominent tympanic bullae

*Nasoincisive notch present

*Wings of the basisphenoid bones form the oval foramen

*No foramen lacernum

*Petrosal and tympanic parts of the temporal bone fused to the squamous part

*Zygomatic process articulates with the frontal process of the zygomatic bone
[[Image:Pig skull.jpg|thumb|right|150px|Pig skull showing tusks - Copyright nabrown RVC]]
===Porcine===
*Thick nucal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Prominent temporal line

*Orbit is incomplete and small

*Strong and deep zygomatic arch

*Large tympanic bullae

*High caudal part of the skull

*Styloid process absent
[[Image:Bird skull.jpg|thumb|right|150px|Bird skull - Copyright nabrown RVC]]
===Avian===
*Pneumatised skull bones
**Spaces in skull bones which connect to airways in the head rather than the air sacs

*Large orbits

*Skull plates are separated by spongy bone

*A single occipital condyle articulates with the atlas allowing more rotation of the head

*In parrots, the nasal bone and frontal bone are joined by a flexible cartliage structure allowing greater jaw opening which is called the craniofacial hinge. This allows kinesis to occur.

*Thin jugal arch (equivalent to zygomatic arch)

*Middle ear contains only the columella (equivalent to the stapes)

==Links==

[[The Skull - Musculoskeletal - Flashcards|Skull Flashcards]]

[[Facial Muscles - Musculoskeletal - Flashcards|Facial Muscles Flashcards]]

Skull and Facial Muscles - Anatomy & Physiology

2008-09-03T13:23:32Z

Katherine: /* Maxilla */

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==Introduction==
[[Image:Deer Skull with Antlers.jpg|thumb|right|150px|Deer Skull - Copyright nabrown RVC]]
The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]], mandible, ossicles of the middle [[Special Senses - Auditory - Anatomy & Physiology|ear]] and the cartilage of the [[Larynx - Anatomy & Physiology|larynx]], nose and [[Special Senses - Auditory - Anatomy & Physiology|ear]]. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in [[Horn - Anatomy & Physiology|horned]] ungulates such as red deer stags.

The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.

The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|intramembranous ossification]].

The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|endochondral and intramembranous ossification]].

The various facial muscles attach onto the skull in different places depending on their function. Movement of the external apendages, [[Mastication|mastication]] and facial expressions all rely on the movement of the facial muscles.

==Structure==

*The skull is made of many smaller bones

*Most of the skull bones are paired

*Cartilage or fibrous tissue separates the bones of the skull in the young animal

*Once growth has ceased, the sutures begin to ossify

==Function==

*Protection of brain

*Support facial muscles by providing origin and insertion sites

*Foramen provide entry and exit places for the vasculature and nervous system

*Defense

==Bones of the Skull==
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===Occipital Bone (os occipitale)===

*Forms the nuchal wall

*Forms the foramen magnum

*Basilar part (pars basilaris)
**Caudal base of the cranium
**Rostral to foramen magnum
**Joined by cartilagenous suture to basisphenoid bone
**Muscular tubercules on ventral surface where the flexors of the head and neck attach
**Caudal cranial fossa enclose the pons and medulla oblongata

*Squamous part (pars squamosa)
**Dorsal to lateral parts and occipital condyles
**Nuchal crest present
***Easily palpable
***Landmark for collection of cerebrospinal fluid (CSF)
**External occipital protuberances present which provide muscle attachment sites for the nuchal ligament

*Lateral parts (partes laterales)
**Lateral borders of foramen magnum
**Occipital condyles present which articulate with the atlas to form the atlanto-occipital joint
**Paracondylar process present which provides muscle attachment sights for muscles of the head
**Hypoglossal canal

===Sphenoid Bone (os sphenoidale)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
*Forms the base of the neurocranium

*Composed of a body and wings

*Bones separated by cartilage which ossifies with age

*Presphenoid (os praespenoidale)
**Rostrally
**Rostral caudal fossa
**Hollow body with sphenoid sinuses located inside
**Sphenoid rostrum present
**Optic chiasma
**Optic canal

*Basisphenoid (os basispenoidalis)
**Caudally
**Median cranial fossa
**The wings oppose the temporal bone, maxilla, orbit and the brain
**Wings form the oval foramen and other foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) carotid notch, oval foramen and spinous notch (in the horse)
**Pterygoid processes present
**Alar canal (rostral and caudal alar foramen)

===Temporal Bone (os temporale)===

*Composed of squamous, petrosal and tympanic parts

*Lateral wall of the cranial cavity

*Articulates with the frontal, pareital and sphenoid bones
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
*Zygomatic process
**On squamous part
**Joins the temporal process of the zygomatic bone to form the zygomatic arch
**Forms the articulating surface of the [[Mastication#Jaw Articulation|temporomandibular joint]]

*Articular tubercle present

*Mandibular fossa present

*Occipital process and retrotympanic process surrounds the external acoustic meatus

*Petrosal part encloses the inner ear
**Internal acoustic meatus present
**Forms mastoid process ventrally
**Styloid process present which attaches the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]
**Stylomastoid foramen present

*Tympanic part is the ventral section of the temporal bone
**Tympanic bulla present
**Tympanic membrane separates tympanic cavity from external acoustic meatus
**Encloses auditory ossicle dorsally
**Musculotubal canal where tensors of the [[Soft Palate - Anatomy & Physiology#Musculature and Innervation|soft palate]] originate

===Frontal Bone (os frontale)===

*Paired

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section
**Forms the zygomatic process laterally
**Forms the dorsal part of the orbit
**Lacrimal gland present
**Temporal line present which extends into the external sagittal crest
**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen
**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle
[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

===Parietal Bone (os parietale)===

*Paired

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone
**Fuses with age

===Ethmoid Bone (os ethmoidale)===
[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]
*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

*The ethmoid bone is separated from the cranial cavity by the cribiform plate
**Numerous small foramina where the olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes
**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses
**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates
**The first endoturbinate forms the dorsal nasal conchae
**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses
**Dorsal nasal meatus
**Middle nasal meatus
**Ventral nasal meatus

===Nasal Bone (os nasale)===
[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]
*Paired

*Forms the roof of the nasal cavity

*Dorsal nasal conchae attach to the ethmoidal crest on the internal surface

*Rostral suture form the apex

*Between the nasal and incisive bones is the nasoincisive notch

===Lacrimal Bone (os lacrimale)===

*Forms part of the lateral wall of the face and orbit

*Situated near the medial canthus

*It articulates with the frontal bone, zygomatic bone and maxilla
**Also articulates with the nasal bone in ruminants and the horse
**Also articulates with the palatine bone in carnivores

*Composed of an orbital and facial part separated by supra- and infraorbital margins

*The nasolacrimal duct is present by the margin of the orbital surface

*Ventral oblique muscle attaches caudal to the margin of the orbital surface

*Nasal surface forms the boundaries of the maxillary and frontal sinuses

===Zygomatic Bone (os zygomaticum)===

*Lateral and ventral to the lacrimal bone

*Forms the orbit and zygomatic arch

*Supraorbital margin formed by the zygomatic process of the temporal bone and the frontal process of the zygomatic bone

*Facial crest present on lateral surface
[[Image:Cow skull lateral view.jpg|thumb|right|150px|Cow skull (incisive bone, nasal bone, maxilla, nasoincisive notch labelled) - Copyright nabrown RVC]]

===Incisive Bone (os incisivium)===

*Paired

*Composed of body, nasal, palatine and alveolar parts

*Joins with the maxilla to form the interalveolar margin

*Forms the rostral part of the facial section of the skull, the roof of the [[Hard Palate - Anatomy & Physiology|hard palate]] and the opening to the nasal cavity

*The alveolar process form conical sockets for the incisor teeth

===Palatine Bone (os palatinum)===

*Paired

*Between the maxilla, sphenoid and pterygoid bones

*Composed of a horizontal plate (forms part of the [[Hard Palate - Anatomy & Physiology|hard palate]]), perpendicular plate (forms the dorsal and lateral walls of the nasopharyngeal meatus) and the choanae

*Nasal crest present on the horizontal plate

*Palatine sinus present on horizontal plate
[[Image:Palatine Bone.jpg|thumb|right|150px|Palatine Bone and Maxilla (Pig) - Copyright nabrown RVC]]

===Vomer===

*Unpaired

*Extends from the choanae of the palatine bone to the floor of the nasal cavity

*Attaches to the median nuchal crest

*Septal sulcus formed which surrounds nasal cavity

===Pterygoid Bone (os pterygoideum)===

*Paired

*Bordered by the palatine and sphenoid bones

*Forms dorsal and lateral walls of the nasopharyngeal cavity

*Pterygoid hamulus present

===Maxilla===
[[Image:Horse Maxilla.jpg|thumb|right|150px|Horse Maxilla - Copyright RVC]]
*Forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Hard Palate - Anatomy & Physiology|hard palate]]

*Forms the ventral nasal conchae

*It articulates with all of the facial bones as it is the largest bone of the face

*The maxillary body encloses the maxillary sinuses and forms the external surface of the face
**Facial crest present

*Infraorbital foramen palpable

*Conchal crest on nasal surface where the ventral nasal conchae attaches

*Lacrimal canal opens into the lacrimal foramen on the nasal surface

*Pterygopalatine surfaces are the caudal part of the maxilla which terminate in the maxillary tubercle where the sphenopalatine, maxillary and caudal palatine foramen are present

*Alveolar processes present separated by interalveolar septa

*Palatine process form the [[Hard Palate - Anatomy & Physiology|hard palate]] with the palatine bone

*Palatine fissure formed at the articulation with the incisive bone

*Nasal surface of palatine process forms the nasal crest and encloses part of the palatine sinuses

*Oral surface has numerous palatine foramina present
[[Image:Cow Mandible.jpg|thumb|right|150px|Mandible of the Cow in situ - Copyright nabrown RVC]]

===Mandible (mandibula)===

*The manidble can be divided into the body and the ramus

*The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally)
**The section of the body which does not support any teeth is called the interalveolar margin or diastema
**Mandibular canal present
**Mental foramen present
**Facial notch on ventral surface where the parotid duct (in herbivores) and facial vessels run
[[Image:Parrot Mandible.jpg|thumb|right|150px|Mandible of the Parrot - Copyright nabrown RVC]]
*The ramus extend from the caudal end of the body dorsally towards the zygomatic arch
**The masseter muscle attaches to the lateral surface at the masseteric fossa
**The medial pterygoid attaches to teh medial surface at the pterygoid fossa
**The angle of the mandible terminates dorsally in the condylar process and the coronoid process which are separated by the mandibular notch
**The temporal muscle inserts onto the coronoid head
**The condylar process articulates with the mandibular process of the skull (see [[Mastication#Jaw Articulation|here]])

==Major Foramen and Canals==

*Jugular Foramen
**Located either side of basilar part of occipital bone
**Adjacent to tympanic bulla
**Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]), vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) and accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
**Internal carotid artery
[[Image:Foramen Magnum.jpg|thumb|right|150px|Foramen Magnum (Horse) - Copyright nabrown RVC]]
*Foramen Magnum
**Formed by occipital bones
**Spinal cord's passage to the neck and body
**Alar ligaments run through
**Vertebral arteries run through
**Spinal arteries run through
**Tectoral membranes run through

*Hypoglossal Canal
**Between paracondylar and condylar processes on lateral part of occipital bone
**Hypoglossal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XII]])
**Condylar artery and vein

*Optic Chiasma
**Runs in transverse depression behind sphenoid rostrum on presphenoid bone
**Path of the optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])
[[Image:Sheep Skull Eye Foramen.jpg|thumb|right|150px|Skull of a Sheep (optic canal, ethmoidal foramen and supraorbital foramen labelled) - Copyright nabrown RVC]]
*Optic Canal
**Ends from optic chiasma over wings of the presphenoid bones
**Optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])

*Oval Foramen
**Caudal wing of the basisphenoid bones
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])

*Alar Canal
**Rostral border of the basisphenoid bone at the base of the pterygoid processes
**Composed of the caudal alar foramen, rostral alar foramen and the small alar foramen
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Temporal artery
[[Image:Pig Foramen Ventral.jpg|thumb|right|150px|Foramen of the Pig (includes jugular, stylomastoid and lacernum - Copyright nabrown RVC]]
*Stylomastoid Foramen
**Situated on the petrosal part of the temporal bone
**Facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])

*Ethmoidal Foramen
**Perforate the orbital part of the frontal bone
**Olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]])
**Ethmoidal artery and vein
[[Image:Cow Skull dorsal view.jpg|thumb|right|150px|Cow skull (supraorbital foramen, temporal line, supramastoid crest and supraorbital groove labelled) - Copyright nabrown RVC]]
*Orbital Fissure
**On the presphenoid bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]]), occulomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and the abducens nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])

*Supraorbital Foramen
**On the frontal bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]])
**Frontal artery and vein

*Infraorbital Foramen
**On the maxilla
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Infraorbital artery and vein
[[Image:Mental and Infraorbital Foramen.jpg|thumb|right|150px|Mental and Infraorbital foramen (dog) - Copyright nabrown RVC]]
*Mental Foramen
**On rostral end of the mandible
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])
**Mental artery and vein

*Palatine Canal
**Runs through horizontal plate of palatine bone
**Palatine artery
**Palatine vein
**Palatine nerves

*Internal Acoustic Meatus
**Medial surface of the petrosal part of the temporal bone
**Facial opening for the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])
**Cochlear opening, dorsal vestibule opening and the ventral vestibule opening for the vestibulocochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VIII]])

==Facial Muscles==
[[Image:Muscles of Mastication.jpg|thumb|right|150px|Muscle of Mastication (dog) - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
The major facial muscles are covered in the following sections of anatomy and physiology:

[[Oral Cavity - Tongue - Anatomy & Physiology#Muscles|Muscles of the Tongue]]

[[Cheeks - Anatomy & Physiology|Muscles of the Cheeks]]

[[Larynx - Anatomy & Physiology#Intrinsic Musculature|Muscles of the Larynx]]

[[Pharynx - Anatomy & Physiology#Musculature|Muscles of the Pharynx]]

[[Special Senses - Visual - Anatomy & Physiology#Around the Eye|Muscles of the Eye]]

[[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|Muscles of the Ear]]

[[Deglutition|Muscles involved in Deglutition]]

[[Mastication|Muscles of Mastication]]

==Species Differences==
[[Image:Pug skull.jpg|thumb|right|150px|Brachycephalic skull (Pug) - Copyright nabrown RVC]]
===Canine===
*Dogs have different skull lengths depending on breed
**Mesocephalic dogs have average conformation
**Dolichocephalic dogs have longer skull lengths
**Brachycephalic dogs have shorter skull lengths

*2 halves of the mandible do not fuse allowing some movement

*External sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament
[[Image:Lion skull.jpg|thumb|right|150px|Feline skull (Lion) - Copyright nabrown RVC]]
===Feline===
*The mandible appears globular in shape

*Large orbits with complete bony margins

*Large tympanic bulla which can be palpated

*2 halves of the mandible do not fuse allowing some movement

*Weak external sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament which is ossified

*Interpareital bone does not fuse entirely in the adult
[[Image:Horse Skull.jpg|thumb|right|150px|Horse Skull - Copyright nabrown RVC]]

===Equine===

*Weak external sagittal crest arises from nuchal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Long skull length

*Orbit placed more laterally with a complete bony rim

*Strong zygomatic arch which continues on to form the facial crest

*Deep nasoincisive notch

*Prominent hamular process

*Large mandible
**Vascular notch on mandible
**High ramus

*Wings of the basisphenoid bones form the oval foramen, spinous notch and carotid notch

*Foramen lacernum present

*Zygomatic process articulates with the zygomatic process of the temporal bone

*Three rows of ethmoturbinates present
[[Image:Sheep skull.jpg|thumb|right|150px|Sheep skull - Copyright nabrown RVC]]
===Ruminant===
*Skull is short and wide

*[[Horn - Anatomy & Physiology|Cornual]] process on frontal bone

*Nuchal crest reduced to nuchal line

*Prominent temporal line

*Elevated orbital ring which is complete

*No facial crest

*Prominent tympanic bullae

*Nasoincisive notch present

*Wings of the basisphenoid bones form the oval foramen

*No foramen lacernum

*Petrosal and tympanic parts of the temporal bone fused to the squamous part

*Zygomatic process articulates with the frontal process of the zygomatic bone
[[Image:Pig skull.jpg|thumb|right|150px|Pig skull showing tusks - Copyright nabrown RVC]]
===Porcine===
*Thick nucal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Prominent temporal line

*Orbit is incomplete and small

*Strong and deep zygomatic arch

*Large tympanic bullae

*High caudal part of the skull

*Styloid process absent
[[Image:Bird skull.jpg|thumb|right|150px|Bird skull - Copyright nabrown RVC]]
===Avian===
*Pneumatised skull bones
**Spaces in skull bones which connect to airways in the head rather than the air sacs

*Large orbits

*Skull plates are separated by spongy bone

*A single occipital condyle articulates with the atlas allowing more rotation of the head

*In parrots, the nasal bone and frontal bone are joined by a flexible cartliage structure allowing greater jaw opening which is called the craniofacial hinge. This allows kinesis to occur.

*Thin jugal arch (equivalent to zygomatic arch)

*Middle ear contains only the columella (equivalent to the stapes)

==Links==

[[The Skull - Musculoskeletal - Flashcards|Skull Flashcards]]

[[Facial Muscles - Musculoskeletal - Flashcards|Facial Muscles Flashcards]]

Skull and Facial Muscles - Anatomy & Physiology

2008-09-03T13:22:11Z

Katherine: /* Maxilla */

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==Introduction==
[[Image:Deer Skull with Antlers.jpg|thumb|right|150px|Deer Skull - Copyright nabrown RVC]]
The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]], mandible, ossicles of the middle [[Special Senses - Auditory - Anatomy & Physiology|ear]] and the cartilage of the [[Larynx - Anatomy & Physiology|larynx]], nose and [[Special Senses - Auditory - Anatomy & Physiology|ear]]. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in [[Horn - Anatomy & Physiology|horned]] ungulates such as red deer stags.

The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.

The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|intramembranous ossification]].

The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|endochondral and intramembranous ossification]].

The various facial muscles attach onto the skull in different places depending on their function. Movement of the external apendages, [[Mastication|mastication]] and facial expressions all rely on the movement of the facial muscles.

==Structure==

*The skull is made of many smaller bones

*Most of the skull bones are paired

*Cartilage or fibrous tissue separates the bones of the skull in the young animal

*Once growth has ceased, the sutures begin to ossify

==Function==

*Protection of brain

*Support facial muscles by providing origin and insertion sites

*Foramen provide entry and exit places for the vasculature and nervous system

*Defense

==Bones of the Skull==
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===Occipital Bone (os occipitale)===

*Forms the nuchal wall

*Forms the foramen magnum

*Basilar part (pars basilaris)
**Caudal base of the cranium
**Rostral to foramen magnum
**Joined by cartilagenous suture to basisphenoid bone
**Muscular tubercules on ventral surface where the flexors of the head and neck attach
**Caudal cranial fossa enclose the pons and medulla oblongata

*Squamous part (pars squamosa)
**Dorsal to lateral parts and occipital condyles
**Nuchal crest present
***Easily palpable
***Landmark for collection of cerebrospinal fluid (CSF)
**External occipital protuberances present which provide muscle attachment sites for the nuchal ligament

*Lateral parts (partes laterales)
**Lateral borders of foramen magnum
**Occipital condyles present which articulate with the atlas to form the atlanto-occipital joint
**Paracondylar process present which provides muscle attachment sights for muscles of the head
**Hypoglossal canal

===Sphenoid Bone (os sphenoidale)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
*Forms the base of the neurocranium

*Composed of a body and wings

*Bones separated by cartilage which ossifies with age

*Presphenoid (os praespenoidale)
**Rostrally
**Rostral caudal fossa
**Hollow body with sphenoid sinuses located inside
**Sphenoid rostrum present
**Optic chiasma
**Optic canal

*Basisphenoid (os basispenoidalis)
**Caudally
**Median cranial fossa
**The wings oppose the temporal bone, maxilla, orbit and the brain
**Wings form the oval foramen and other foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) carotid notch, oval foramen and spinous notch (in the horse)
**Pterygoid processes present
**Alar canal (rostral and caudal alar foramen)

===Temporal Bone (os temporale)===

*Composed of squamous, petrosal and tympanic parts

*Lateral wall of the cranial cavity

*Articulates with the frontal, pareital and sphenoid bones
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
*Zygomatic process
**On squamous part
**Joins the temporal process of the zygomatic bone to form the zygomatic arch
**Forms the articulating surface of the [[Mastication#Jaw Articulation|temporomandibular joint]]

*Articular tubercle present

*Mandibular fossa present

*Occipital process and retrotympanic process surrounds the external acoustic meatus

*Petrosal part encloses the inner ear
**Internal acoustic meatus present
**Forms mastoid process ventrally
**Styloid process present which attaches the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]
**Stylomastoid foramen present

*Tympanic part is the ventral section of the temporal bone
**Tympanic bulla present
**Tympanic membrane separates tympanic cavity from external acoustic meatus
**Encloses auditory ossicle dorsally
**Musculotubal canal where tensors of the [[Soft Palate - Anatomy & Physiology#Musculature and Innervation|soft palate]] originate

===Frontal Bone (os frontale)===

*Paired

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section
**Forms the zygomatic process laterally
**Forms the dorsal part of the orbit
**Lacrimal gland present
**Temporal line present which extends into the external sagittal crest
**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen
**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle
[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

===Parietal Bone (os parietale)===

*Paired

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone
**Fuses with age

===Ethmoid Bone (os ethmoidale)===
[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]
*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

*The ethmoid bone is separated from the cranial cavity by the cribiform plate
**Numerous small foramina where the olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes
**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses
**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates
**The first endoturbinate forms the dorsal nasal conchae
**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses
**Dorsal nasal meatus
**Middle nasal meatus
**Ventral nasal meatus

===Nasal Bone (os nasale)===
[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]
*Paired

*Forms the roof of the nasal cavity

*Dorsal nasal conchae attach to the ethmoidal crest on the internal surface

*Rostral suture form the apex

*Between the nasal and incisive bones is the nasoincisive notch

===Lacrimal Bone (os lacrimale)===

*Forms part of the lateral wall of the face and orbit

*Situated near the medial canthus

*It articulates with the frontal bone, zygomatic bone and maxilla
**Also articulates with the nasal bone in ruminants and the horse
**Also articulates with the palatine bone in carnivores

*Composed of an orbital and facial part separated by supra- and infraorbital margins

*The nasolacrimal duct is present by the margin of the orbital surface

*Ventral oblique muscle attaches caudal to the margin of the orbital surface

*Nasal surface forms the boundaries of the maxillary and frontal sinuses

===Zygomatic Bone (os zygomaticum)===

*Lateral and ventral to the lacrimal bone

*Forms the orbit and zygomatic arch

*Supraorbital margin formed by the zygomatic process of the temporal bone and the frontal process of the zygomatic bone

*Facial crest present on lateral surface
[[Image:Cow skull lateral view.jpg|thumb|right|150px|Cow skull (incisive bone, nasal bone, maxilla, nasoincisive notch labelled) - Copyright nabrown RVC]]

===Incisive Bone (os incisivium)===

*Paired

*Composed of body, nasal, palatine and alveolar parts

*Joins with the maxilla to form the interalveolar margin

*Forms the rostral part of the facial section of the skull, the roof of the [[Hard Palate - Anatomy & Physiology|hard palate]] and the opening to the nasal cavity

*The alveolar process form conical sockets for the incisor teeth

===Palatine Bone (os palatinum)===

*Paired

*Between the maxilla, sphenoid and pterygoid bones

*Composed of a horizontal plate (forms part of the [[Hard Palate - Anatomy & Physiology|hard palate]]), perpendicular plate (forms the dorsal and lateral walls of the nasopharyngeal meatus) and the choanae

*Nasal crest present on the horizontal plate

*Palatine sinus present on horizontal plate
[[Image:Palatine Bone.jpg|thumb|right|150px|Palatine Bone and Maxilla (Pig) - Copyright nabrown RVC]]

===Vomer===

*Unpaired

*Extends from the choanae of the palatine bone to the floor of the nasal cavity

*Attaches to the median nuchal crest

*Septal sulcus formed which surrounds nasal cavity

===Pterygoid Bone (os pterygoideum)===

*Paired

*Bordered by the palatine and sphenoid bones

*Forms dorsal and lateral walls of the nasopharyngeal cavity

*Pterygoid hamulus present

===Maxilla===
[[Image:Horse Maxilla.jpg|thumb|right|150px|Horse Maxilla - Copyright RVC]]
*Forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Hard Palate - Anatomy & Physiology|hard palate]]

*Forms the ventral nasal conchae

*It articulates with all of the facial bones as it is the largest bone of the face

*The maxillary body encloses the maxillary sinuses and forms the external surface of the face
**Facial crest present

*Infraorbital foramen palpable

*Conchal crest on nasal surface where the ventral nasal conchae attaches

*Lacrimal canal opens into the lacrimal foramen on the nasal surface

*Pterygopalatine surfaces are the caudal part of the maxilla which terminate in the maxillary tubercle where the sphenopalatine, maxillary and caudal palatine foramen are present

*Alveolar processes present separated by interalveolar septa

*Palatine process form the [[Hard Palate - Anatomy & Physiology|hard palate]] with the palatine bone

*Palatine fissure formed at the articulation with the incisive bone

*Nasal surface of palatine process froms the nasal crest and encloses part of the palatine sinuses

*Oral surface has numerous palatine foramina present
[[Image:Cow Mandible.jpg|thumb|right|150px|Mandible of the Cow in situ - Copyright nabrown RVC]]

===Mandible (mandibula)===

*The manidble can be divided into the body and the ramus

*The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally)
**The section of the body which does not support any teeth is called the interalveolar margin or diastema
**Mandibular canal present
**Mental foramen present
**Facial notch on ventral surface where the parotid duct (in herbivores) and facial vessels run
[[Image:Parrot Mandible.jpg|thumb|right|150px|Mandible of the Parrot - Copyright nabrown RVC]]
*The ramus extend from the caudal end of the body dorsally towards the zygomatic arch
**The masseter muscle attaches to the lateral surface at the masseteric fossa
**The medial pterygoid attaches to teh medial surface at the pterygoid fossa
**The angle of the mandible terminates dorsally in the condylar process and the coronoid process which are separated by the mandibular notch
**The temporal muscle inserts onto the coronoid head
**The condylar process articulates with the mandibular process of the skull (see [[Mastication#Jaw Articulation|here]])

==Major Foramen and Canals==

*Jugular Foramen
**Located either side of basilar part of occipital bone
**Adjacent to tympanic bulla
**Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]), vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) and accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
**Internal carotid artery
[[Image:Foramen Magnum.jpg|thumb|right|150px|Foramen Magnum (Horse) - Copyright nabrown RVC]]
*Foramen Magnum
**Formed by occipital bones
**Spinal cord's passage to the neck and body
**Alar ligaments run through
**Vertebral arteries run through
**Spinal arteries run through
**Tectoral membranes run through

*Hypoglossal Canal
**Between paracondylar and condylar processes on lateral part of occipital bone
**Hypoglossal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XII]])
**Condylar artery and vein

*Optic Chiasma
**Runs in transverse depression behind sphenoid rostrum on presphenoid bone
**Path of the optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])
[[Image:Sheep Skull Eye Foramen.jpg|thumb|right|150px|Skull of a Sheep (optic canal, ethmoidal foramen and supraorbital foramen labelled) - Copyright nabrown RVC]]
*Optic Canal
**Ends from optic chiasma over wings of the presphenoid bones
**Optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])

*Oval Foramen
**Caudal wing of the basisphenoid bones
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])

*Alar Canal
**Rostral border of the basisphenoid bone at the base of the pterygoid processes
**Composed of the caudal alar foramen, rostral alar foramen and the small alar foramen
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Temporal artery
[[Image:Pig Foramen Ventral.jpg|thumb|right|150px|Foramen of the Pig (includes jugular, stylomastoid and lacernum - Copyright nabrown RVC]]
*Stylomastoid Foramen
**Situated on the petrosal part of the temporal bone
**Facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])

*Ethmoidal Foramen
**Perforate the orbital part of the frontal bone
**Olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]])
**Ethmoidal artery and vein
[[Image:Cow Skull dorsal view.jpg|thumb|right|150px|Cow skull (supraorbital foramen, temporal line, supramastoid crest and supraorbital groove labelled) - Copyright nabrown RVC]]
*Orbital Fissure
**On the presphenoid bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]]), occulomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and the abducens nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])

*Supraorbital Foramen
**On the frontal bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]])
**Frontal artery and vein

*Infraorbital Foramen
**On the maxilla
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Infraorbital artery and vein
[[Image:Mental and Infraorbital Foramen.jpg|thumb|right|150px|Mental and Infraorbital foramen (dog) - Copyright nabrown RVC]]
*Mental Foramen
**On rostral end of the mandible
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])
**Mental artery and vein

*Palatine Canal
**Runs through horizontal plate of palatine bone
**Palatine artery
**Palatine vein
**Palatine nerves

*Internal Acoustic Meatus
**Medial surface of the petrosal part of the temporal bone
**Facial opening for the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])
**Cochlear opening, dorsal vestibule opening and the ventral vestibule opening for the vestibulocochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VIII]])

==Facial Muscles==
[[Image:Muscles of Mastication.jpg|thumb|right|150px|Muscle of Mastication (dog) - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
The major facial muscles are covered in the following sections of anatomy and physiology:

[[Oral Cavity - Tongue - Anatomy & Physiology#Muscles|Muscles of the Tongue]]

[[Cheeks - Anatomy & Physiology|Muscles of the Cheeks]]

[[Larynx - Anatomy & Physiology#Intrinsic Musculature|Muscles of the Larynx]]

[[Pharynx - Anatomy & Physiology#Musculature|Muscles of the Pharynx]]

[[Special Senses - Visual - Anatomy & Physiology#Around the Eye|Muscles of the Eye]]

[[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|Muscles of the Ear]]

[[Deglutition|Muscles involved in Deglutition]]

[[Mastication|Muscles of Mastication]]

==Species Differences==
[[Image:Pug skull.jpg|thumb|right|150px|Brachycephalic skull (Pug) - Copyright nabrown RVC]]
===Canine===
*Dogs have different skull lengths depending on breed
**Mesocephalic dogs have average conformation
**Dolichocephalic dogs have longer skull lengths
**Brachycephalic dogs have shorter skull lengths

*2 halves of the mandible do not fuse allowing some movement

*External sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament
[[Image:Lion skull.jpg|thumb|right|150px|Feline skull (Lion) - Copyright nabrown RVC]]
===Feline===
*The mandible appears globular in shape

*Large orbits with complete bony margins

*Large tympanic bulla which can be palpated

*2 halves of the mandible do not fuse allowing some movement

*Weak external sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament which is ossified

*Interpareital bone does not fuse entirely in the adult
[[Image:Horse Skull.jpg|thumb|right|150px|Horse Skull - Copyright nabrown RVC]]

===Equine===

*Weak external sagittal crest arises from nuchal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Long skull length

*Orbit placed more laterally with a complete bony rim

*Strong zygomatic arch which continues on to form the facial crest

*Deep nasoincisive notch

*Prominent hamular process

*Large mandible
**Vascular notch on mandible
**High ramus

*Wings of the basisphenoid bones form the oval foramen, spinous notch and carotid notch

*Foramen lacernum present

*Zygomatic process articulates with the zygomatic process of the temporal bone

*Three rows of ethmoturbinates present
[[Image:Sheep skull.jpg|thumb|right|150px|Sheep skull - Copyright nabrown RVC]]
===Ruminant===
*Skull is short and wide

*[[Horn - Anatomy & Physiology|Cornual]] process on frontal bone

*Nuchal crest reduced to nuchal line

*Prominent temporal line

*Elevated orbital ring which is complete

*No facial crest

*Prominent tympanic bullae

*Nasoincisive notch present

*Wings of the basisphenoid bones form the oval foramen

*No foramen lacernum

*Petrosal and tympanic parts of the temporal bone fused to the squamous part

*Zygomatic process articulates with the frontal process of the zygomatic bone
[[Image:Pig skull.jpg|thumb|right|150px|Pig skull showing tusks - Copyright nabrown RVC]]
===Porcine===
*Thick nucal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Prominent temporal line

*Orbit is incomplete and small

*Strong and deep zygomatic arch

*Large tympanic bullae

*High caudal part of the skull

*Styloid process absent
[[Image:Bird skull.jpg|thumb|right|150px|Bird skull - Copyright nabrown RVC]]
===Avian===
*Pneumatised skull bones
**Spaces in skull bones which connect to airways in the head rather than the air sacs

*Large orbits

*Skull plates are separated by spongy bone

*A single occipital condyle articulates with the atlas allowing more rotation of the head

*In parrots, the nasal bone and frontal bone are joined by a flexible cartliage structure allowing greater jaw opening which is called the craniofacial hinge. This allows kinesis to occur.

*Thin jugal arch (equivalent to zygomatic arch)

*Middle ear contains only the columella (equivalent to the stapes)

==Links==

[[The Skull - Musculoskeletal - Flashcards|Skull Flashcards]]

[[Facial Muscles - Musculoskeletal - Flashcards|Facial Muscles Flashcards]]

Skull and Facial Muscles - Anatomy & Physiology

2008-09-03T13:15:43Z

Katherine: /* Vomer */

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==Introduction==
[[Image:Deer Skull with Antlers.jpg|thumb|right|150px|Deer Skull - Copyright nabrown RVC]]
The shape and size of the skull varies widely, not only between species but also with age, breed and sex of similar species. The skull is divided into three components- the neurocranium, the dermatocranium and the viscerocranium. The skull also includes the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]], mandible, ossicles of the middle [[Special Senses - Auditory - Anatomy & Physiology|ear]] and the cartilage of the [[Larynx - Anatomy & Physiology|larynx]], nose and [[Special Senses - Auditory - Anatomy & Physiology|ear]]. The skull protects the brain and head against injury and supports the structures of the face. In some animals the skull is also used for defensive actions, for example in [[Horn - Anatomy & Physiology|horned]] ungulates such as red deer stags.

The neurocranium develops from the neural crest and mesoderm and undergoes endochondral ossification. It lies ventral to the brain.

The dermatocranium lies dorsal to the brain and develops from the neural crest and mesoderm. It undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|intramembranous ossification]].

The viscerocranium is the pharyngeal skeleton. It is derived only from the neural crest and undergoes [[Bones and Cartilage - Anatomy & Physiology#Development of Bone and Cartilage|endochondral and intramembranous ossification]].

The various facial muscles attach onto the skull in different places depending on their function. Movement of the external apendages, [[Mastication|mastication]] and facial expressions all rely on the movement of the facial muscles.

==Structure==

*The skull is made of many smaller bones

*Most of the skull bones are paired

*Cartilage or fibrous tissue separates the bones of the skull in the young animal

*Once growth has ceased, the sutures begin to ossify

==Function==

*Protection of brain

*Support facial muscles by providing origin and insertion sites

*Foramen provide entry and exit places for the vasculature and nervous system

*Defense

==Bones of the Skull==
[[Image:Pig skull dorsal.jpg|thumb|right|150px|Pig skull (nuchal crest, nasal bone, frontal bone, pareital bone, zygomatic process of the temporal bone and coronoid process of the mandible labelled) - Copyright nabrown RVC]]
===Occipital Bone (os occipitale)===

*Forms the nuchal wall

*Forms the foramen magnum

*Basilar part (pars basilaris)
**Caudal base of the cranium
**Rostral to foramen magnum
**Joined by cartilagenous suture to basisphenoid bone
**Muscular tubercules on ventral surface where the flexors of the head and neck attach
**Caudal cranial fossa enclose the pons and medulla oblongata

*Squamous part (pars squamosa)
**Dorsal to lateral parts and occipital condyles
**Nuchal crest present
***Easily palpable
***Landmark for collection of cerebrospinal fluid (CSF)
**External occipital protuberances present which provide muscle attachment sites for the nuchal ligament

*Lateral parts (partes laterales)
**Lateral borders of foramen magnum
**Occipital condyles present which articulate with the atlas to form the atlanto-occipital joint
**Paracondylar process present which provides muscle attachment sights for muscles of the head
**Hypoglossal canal

===Sphenoid Bone (os sphenoidale)===
[[Image:Pig skull ventral view.jpg|thumb|right|150px|Ventral view pig skull (vomer, occipital condyle, sphenoid, pterygoid bone, hamulus labelled)- Copyright nabrown RVC]]
*Forms the base of the neurocranium

*Composed of a body and wings

*Bones separated by cartilage which ossifies with age

*Presphenoid (os praespenoidale)
**Rostrally
**Rostral caudal fossa
**Hollow body with sphenoid sinuses located inside
**Sphenoid rostrum present
**Optic chiasma
**Optic canal

*Basisphenoid (os basispenoidalis)
**Caudally
**Median cranial fossa
**The wings oppose the temporal bone, maxilla, orbit and the brain
**Wings form the oval foramen and other foramen (see [[Skull and Facial Muscles - Anatomy & Physiology#Species Differences|species differences]]) carotid notch, oval foramen and spinous notch (in the horse)
**Pterygoid processes present
**Alar canal (rostral and caudal alar foramen)

===Temporal Bone (os temporale)===

*Composed of squamous, petrosal and tympanic parts

*Lateral wall of the cranial cavity

*Articulates with the frontal, pareital and sphenoid bones
[[Image:Zygomatic arch.jpg|thumb|right|150px|Zygomatic Arch (Dog) - Copyright nabrown RVC]]
*Zygomatic process
**On squamous part
**Joins the temporal process of the zygomatic bone to form the zygomatic arch
**Forms the articulating surface of the [[Mastication#Jaw Articulation|temporomandibular joint]]

*Articular tubercle present

*Mandibular fossa present

*Occipital process and retrotympanic process surrounds the external acoustic meatus

*Petrosal part encloses the inner ear
**Internal acoustic meatus present
**Forms mastoid process ventrally
**Styloid process present which attaches the [[Hyoid Apparatus - Anatomy & Physiology|hyoid apparatus]]
**Stylomastoid foramen present

*Tympanic part is the ventral section of the temporal bone
**Tympanic bulla present
**Tympanic membrane separates tympanic cavity from external acoustic meatus
**Encloses auditory ossicle dorsally
**Musculotubal canal where tensors of the [[Soft Palate - Anatomy & Physiology#Musculature and Innervation|soft palate]] originate

===Frontal Bone (os frontale)===

*Paired

*Joined by the interfrontal suture

*Between the cranium and the face

*Encloses the frontal sinuses

*The nasal and lacrimal bones border the frontal squama section
**Forms the zygomatic process laterally
**Forms the dorsal part of the orbit
**Lacrimal gland present
**Temporal line present which extends into the external sagittal crest
**Cornual processes in [[Horn - Anatomy & Physiology|horned]] ruminants

*The nasal section is the rostral part of the frontal bone

*Orbital part is perforated by the ethmoidal foramen
**Medially the dorsal oblique muscle of the eyeball attaches

*Temporal part provides the muscle attachments for the temporalis muscle
[[Image:Pareital Bone.jpg|thumb|right|150px|Parietal bone, occipital bone and external acoustic meatus (Horse) - Copyright nabrown RVC]]

===Parietal Bone (os parietale)===

*Paired

*Forms the dorsolateral wall of the cranium

*Occipital bone caudally

*Frontal bone rostrally

*Composed of a pareital plane, temporal plane and a nuchal plane (in the ox)

*Internally the grooves and ridges correspond with the gyri and sulci of the brain

*Interpareital bone between the occipital bone and the pareital bone
**Fuses with age

===Ethmoid Bone (os ethmoidale)===
[[Image:Nasal Cavities.jpg|thumb|right|150px|Nasal Cavities - Copyright David Bainbridge]]
*Forms part of the cranial and facial parts of the skull

*Located deep in the orbit

*External lamina consists of the roof plate, floor plate and paired orbital plates

*The ethmoid bone is separated from the cranial cavity by the cribiform plate
**Numerous small foramina where the olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]]) passes through

*The perpendicular plate splits the ethmoid into two halves

*The ethmoid larbyrinth prodrudes from the ethmoid tubes
**Composed of two rows of ethmoturbinates and air filled ethmoidal meatuses
**Secondary ethmoturbinates may also be present

*Ethmoturbinates divided into endoturbinates and ectoturbinates
**The first endoturbinate forms the dorsal nasal conchae
**The second endoturbinate froms the middle nasal conchae

*The endoturbinates form 3 nasal meatuses
**Dorsal nasal meatus
**Middle nasal meatus
**Ventral nasal meatus

===Nasal Bone (os nasale)===
[[Image:Ethmoid Turbinates.jpg|thumb|right|150px|Ethmoid Turbinates (Dog) - Copyright nabrown RVC]]
*Paired

*Forms the roof of the nasal cavity

*Dorsal nasal conchae attach to the ethmoidal crest on the internal surface

*Rostral suture form the apex

*Between the nasal and incisive bones is the nasoincisive notch

===Lacrimal Bone (os lacrimale)===

*Forms part of the lateral wall of the face and orbit

*Situated near the medial canthus

*It articulates with the frontal bone, zygomatic bone and maxilla
**Also articulates with the nasal bone in ruminants and the horse
**Also articulates with the palatine bone in carnivores

*Composed of an orbital and facial part separated by supra- and infraorbital margins

*The nasolacrimal duct is present by the margin of the orbital surface

*Ventral oblique muscle attaches caudal to the margin of the orbital surface

*Nasal surface forms the boundaries of the maxillary and frontal sinuses

===Zygomatic Bone (os zygomaticum)===

*Lateral and ventral to the lacrimal bone

*Forms the orbit and zygomatic arch

*Supraorbital margin formed by the zygomatic process of the temporal bone and the frontal process of the zygomatic bone

*Facial crest present on lateral surface
[[Image:Cow skull lateral view.jpg|thumb|right|150px|Cow skull (incisive bone, nasal bone, maxilla, nasoincisive notch labelled) - Copyright nabrown RVC]]

===Incisive Bone (os incisivium)===

*Paired

*Composed of body, nasal, palatine and alveolar parts

*Joins with the maxilla to form the interalveolar margin

*Forms the rostral part of the facial section of the skull, the roof of the [[Hard Palate - Anatomy & Physiology|hard palate]] and the opening to the nasal cavity

*The alveolar process form conical sockets for the incisor teeth

===Palatine Bone (os palatinum)===

*Paired

*Between the maxilla, sphenoid and pterygoid bones

*Composed of a horizontal plate (forms part of the [[Hard Palate - Anatomy & Physiology|hard palate]]), perpendicular plate (forms the dorsal and lateral walls of the nasopharyngeal meatus) and the choanae

*Nasal crest present on the horizontal plate

*Palatine sinus present on horizontal plate
[[Image:Palatine Bone.jpg|thumb|right|150px|Palatine Bone and Maxilla (Pig) - Copyright nabrown RVC]]

===Vomer===

*Unpaired

*Extends from the choanae of the palatine bone to the floor of the nasal cavity

*Attaches to the median nuchal crest

*Septal sulcus formed which surrounds nasal cavity

===Pterygoid Bone (os pterygoideum)===

*Paired

*Bordered by the palatine and sphenoid bones

*Forms dorsal and lateral walls of the nasopharyngeal cavity

*Pterygoid hamulus present

===Maxilla===
[[Image:Horse Maxilla.jpg|thumb|right|150px|Horse Maxilla - Copyright RVC]]
*Forms most of the facial part of the skull, including the lateral walls of the face, nasal cavity, [[Oral Cavity Overview - Anatomy & Physiology|oral cavity]] and [[Hard Palate - Anatomy & Physiology|hard palate]]

*Forms the ventral nasal conchae

*It articulates with all of the facial bones as it is the largest bone of the face

*The maxillary body encloses the maxillary sinuses and forms the external surface of the face
**Facial crest present

*Infraorbital foramen palpatable

*Conchal crest on nasal surface where the ventral nasal conchae attaches

*Lacrimal canal opens into the lacrimal foramen on the nasal surface

*Pterygopalatine surfaces are the caudal part of the maxilla which terminate in the maxillary tubercle where the sphenopalatine, maxillary and caudal palatine foramen are present

*Alveolar processes present separated by interalveolar septa

*Palatine process form the [[Hard Palate - Anatomy & Physiology|hard palate]] with the palatine bone

*Palatine fissure formed at the articulation with the incisive bone

*Nasal surface of palatine process froms the nasal crest and encloses part of the palatine sinuses

*Oral surface has numerous palatine foramina present
[[Image:Cow Mandible.jpg|thumb|right|150px|Mandible of the Cow in situ - Copyright nabrown RVC]]

===Mandible (mandibula)===

*The manidble can be divided into the body and the ramus

*The body of the mandible supports the incisor teeth (rostrally) and cheek teeth (caudally)
**The section of the body which does not support any teeth is called the interalveolar margin or diastema
**Mandibular canal present
**Mental foramen present
**Facial notch on ventral surface where the parotid duct (in herbivores) and facial vessels run
[[Image:Parrot Mandible.jpg|thumb|right|150px|Mandible of the Parrot - Copyright nabrown RVC]]
*The ramus extend from the caudal end of the body dorsally towards the zygomatic arch
**The masseter muscle attaches to the lateral surface at the masseteric fossa
**The medial pterygoid attaches to teh medial surface at the pterygoid fossa
**The angle of the mandible terminates dorsally in the condylar process and the coronoid process which are separated by the mandibular notch
**The temporal muscle inserts onto the coronoid head
**The condylar process articulates with the mandibular process of the skull (see [[Mastication#Jaw Articulation|here]])

==Major Foramen and Canals==

*Jugular Foramen
**Located either side of basilar part of occipital bone
**Adjacent to tympanic bulla
**Glossopharyngeal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IX]]), vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) and accessory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XI]])
**Internal carotid artery
[[Image:Foramen Magnum.jpg|thumb|right|150px|Foramen Magnum (Horse) - Copyright nabrown RVC]]
*Foramen Magnum
**Formed by occipital bones
**Spinal cord's passage to the neck and body
**Alar ligaments run through
**Vertebral arteries run through
**Spinal arteries run through
**Tectoral membranes run through

*Hypoglossal Canal
**Between paracondylar and condylar processes on lateral part of occipital bone
**Hypoglossal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN XII]])
**Condylar artery and vein

*Optic Chiasma
**Runs in transverse depression behind sphenoid rostrum on presphenoid bone
**Path of the optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])
[[Image:Sheep Skull Eye Foramen.jpg|thumb|right|150px|Skull of a Sheep (optic canal, ethmoidal foramen and supraorbital foramen labelled) - Copyright nabrown RVC]]
*Optic Canal
**Ends from optic chiasma over wings of the presphenoid bones
**Optic nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN II]])

*Oval Foramen
**Caudal wing of the basisphenoid bones
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])

*Alar Canal
**Rostral border of the basisphenoid bone at the base of the pterygoid processes
**Composed of the caudal alar foramen, rostral alar foramen and the small alar foramen
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Temporal artery
[[Image:Pig Foramen Ventral.jpg|thumb|right|150px|Foramen of the Pig (includes jugular, stylomastoid and lacernum - Copyright nabrown RVC]]
*Stylomastoid Foramen
**Situated on the petrosal part of the temporal bone
**Facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])

*Ethmoidal Foramen
**Perforate the orbital part of the frontal bone
**Olfactory nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN I]])
**Ethmoidal artery and vein
[[Image:Cow Skull dorsal view.jpg|thumb|right|150px|Cow skull (supraorbital foramen, temporal line, supramastoid crest and supraorbital groove labelled) - Copyright nabrown RVC]]
*Orbital Fissure
**On the presphenoid bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]]), occulomotor nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN III]]), trochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN IV]]) and the abducens nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VI]])

*Supraorbital Foramen
**On the frontal bone
**Opthalmic branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V1]])
**Frontal artery and vein

*Infraorbital Foramen
**On the maxilla
**Maxillary branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V2]])
**Infraorbital artery and vein
[[Image:Mental and Infraorbital Foramen.jpg|thumb|right|150px|Mental and Infraorbital foramen (dog) - Copyright nabrown RVC]]
*Mental Foramen
**On rostral end of the mandible
**Mandibular branch of the trigeminal nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN V3]])
**Mental artery and vein

*Palatine Canal
**Runs through horizontal plate of palatine bone
**Palatine artery
**Palatine vein
**Palatine nerves

*Internal Acoustic Meatus
**Medial surface of the petrosal part of the temporal bone
**Facial opening for the facial nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VII]])
**Cochlear opening, dorsal vestibule opening and the ventral vestibule opening for the vestibulocochlear nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN VIII]])

==Facial Muscles==
[[Image:Muscles of Mastication.jpg|thumb|right|150px|Muscle of Mastication (dog) - Copyright C.Clarkson and T.F.Fletcher University of Minnesota]]
The major facial muscles are covered in the following sections of anatomy and physiology:

[[Oral Cavity - Tongue - Anatomy & Physiology#Muscles|Muscles of the Tongue]]

[[Cheeks - Anatomy & Physiology|Muscles of the Cheeks]]

[[Larynx - Anatomy & Physiology#Intrinsic Musculature|Muscles of the Larynx]]

[[Pharynx - Anatomy & Physiology#Musculature|Muscles of the Pharynx]]

[[Special Senses - Visual - Anatomy & Physiology#Around the Eye|Muscles of the Eye]]

[[Special Senses - Auditory - Anatomy & Physiology#Outer Ear|Muscles of the Ear]]

[[Deglutition|Muscles involved in Deglutition]]

[[Mastication|Muscles of Mastication]]

==Species Differences==
[[Image:Pug skull.jpg|thumb|right|150px|Brachycephalic skull (Pug) - Copyright nabrown RVC]]
===Canine===
*Dogs have different skull lengths depending on breed
**Mesocephalic dogs have average conformation
**Dolichocephalic dogs have longer skull lengths
**Brachycephalic dogs have shorter skull lengths

*2 halves of the mandible do not fuse allowing some movement

*External sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament
[[Image:Lion skull.jpg|thumb|right|150px|Feline skull (Lion) - Copyright nabrown RVC]]
===Feline===
*The mandible appears globular in shape

*Large orbits with complete bony margins

*Large tympanic bulla which can be palpated

*2 halves of the mandible do not fuse allowing some movement

*Weak external sagittal crest arises from nuchal crest

*Wings of the basisphenoid bones form the oval foramen, spinous foramen and carotid canal

*No foramen lacernum

*Styloid process absent

*Dorsal margin of orbit formed by the orbital ligament which is ossified

*Interpareital bone does not fuse entirely in the adult
[[Image:Horse Skull.jpg|thumb|right|150px|Horse Skull - Copyright nabrown RVC]]

===Equine===

*Weak external sagittal crest arises from nuchal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Long skull length

*Orbit placed more laterally with a complete bony rim

*Strong zygomatic arch which continues on to form the facial crest

*Deep nasoincisive notch

*Prominent hamular process

*Large mandible
**Vascular notch on mandible
**High ramus

*Wings of the basisphenoid bones form the oval foramen, spinous notch and carotid notch

*Foramen lacernum present

*Zygomatic process articulates with the zygomatic process of the temporal bone

*Three rows of ethmoturbinates present
[[Image:Sheep skull.jpg|thumb|right|150px|Sheep skull - Copyright nabrown RVC]]
===Ruminant===
*Skull is short and wide

*[[Horn - Anatomy & Physiology|Cornual]] process on frontal bone

*Nuchal crest reduced to nuchal line

*Prominent temporal line

*Elevated orbital ring which is complete

*No facial crest

*Prominent tympanic bullae

*Nasoincisive notch present

*Wings of the basisphenoid bones form the oval foramen

*No foramen lacernum

*Petrosal and tympanic parts of the temporal bone fused to the squamous part

*Zygomatic process articulates with the frontal process of the zygomatic bone
[[Image:Pig skull.jpg|thumb|right|150px|Pig skull showing tusks - Copyright nabrown RVC]]
===Porcine===
*Thick nucal crest

*Internal sagittal crest on the internal surface of the pareital bone

*Prominent temporal line

*Orbit is incomplete and small

*Strong and deep zygomatic arch

*Large tympanic bullae

*High caudal part of the skull

*Styloid process absent
[[Image:Bird skull.jpg|thumb|right|150px|Bird skull - Copyright nabrown RVC]]
===Avian===
*Pneumatised skull bones
**Spaces in skull bones which connect to airways in the head rather than the air sacs

*Large orbits

*Skull plates are separated by spongy bone

*A single occipital condyle articulates with the atlas allowing more rotation of the head

*In parrots, the nasal bone and frontal bone are joined by a flexible cartliage structure allowing greater jaw opening which is called the craniofacial hinge. This allows kinesis to occur.

*Thin jugal arch (equivalent to zygomatic arch)

*Middle ear contains only the columella (equivalent to the stapes)

==Links==

[[The Skull - Musculoskeletal - Flashcards|Skull Flashcards]]

[[Facial Muscles - Musculoskeletal - Flashcards|Facial Muscles Flashcards]]

Ribs and Sternum - Anatomy & Physiology

2008-09-03T12:36:33Z

Katherine: /* Thoracic Musculature */

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=Costae=
[[Image:Thorax skeleton.png|thumb|right|150px|Canine thorax showing placement of mitral valve - Wikimedia Commons 2008]]
*Arranged in pairs and articulate with two successive vertebrae
*Bony dorsal part, body of rib, and ventral costal cartilage
*Increase in length, curvature and amount of cartilage craniocaudally
*Cartilage of last rib may fail to join that of its neighbor: said to be '''floating'''
*Join ventrally on the midline at the '''Sternum''', which is comprised of three parts
**'''Manubrium''': most cranial, projects beyond the first set of ribs and can be palpated
**Body: segmented '''sternebrae''' joined by cartilage in young animals that is later replaced by bone
**'''Xiphoid Cartilage''': caudal end that projects between lower ends of costal arches, providing attachment for the '''linea alba'''
*Costal Joints:
**Costovertebral joint: head of rib articulates with vertebral column, ball and socket with very restricted mobility
**Costotransverse joint: tubercle articulates with vertebra, sliding joint
**Costosternal joints:
***Interchondral joints: asternal ribs, elastic syndesmoses
***Intersternal joints: impermanent synchondroses

=Thoracic Musculature=
[[Image: Cat diaphragm.jpg|thumb|right|150px|Cat diaphragm- Copyright Uwe Gille]]
*Primarily concerned with respiration
**Inspiratory muscles enlarge the thoracic cavity
**Expiratory muscles diminish the cavity and force air out
*The most important thoracic muscle is the '''''Diaphragm''''', which separates the thoracic and abdominal cavities

*''Intercostal muscles''
**Dome-shaped, convex on its cranial surface
**Central tendon forms the vertex
***Neutral position (between full inspiration and full expiration): 6th rib behind the '''olecranon'''
**Attaches via muscular periphery to the costal arch
[[Image: Intercostal.JPG|thumb|right|150px|Intercostal muscles with nerve and vessels- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]
**Three openings:
***'''Aortic hilus''' conveying the aorta, azygous vien, and thoracic duct
***'''Oesophageal hiatus''' conveying the oesophagus, vagal trunks and supplying vessels
***'''Caval foramen''' within central tendon conveying [[Liver - Anatomy & Physiology#Vasculature|caudal vena cava]]
**Innervated by the '''phrenic nerve''', which arises from the caudal cervical nerves (C5-C7)

**External fibers run caudoventrally and internal fibers run cranioventrally
**Each is confined to a single intercostal space
*''Transversus thoracis'' arises from and covers the dorsal sternum and inserts on sternal ribs close to the costochondral junctions
*''Rectus thoracis'' covers the ends of the first four ribs in continuation of the ''rectus abdominus''
*''Serratus dorsalis'' overlies the dorsal aspect of the ribs
*Innervation of these muscles is supplied by the '''Intercostal nerves''', which are ventral branches of the thoracic spinal nerves

=Abdominal Musculature=
*Ventrolateral Muscles: flanks and abdominal floor
**All muscles join via aponeuroses in the '''linea alba''' at midline, which runs from the [[Ribs and Sternum - Anatomy & Physiology#Costae|xiphoid process]] to the [[Pelvis - Anatomy & Physiology#Pelvic Girdle|pelvic symphysis]] via the prepubic tendon, ensheathing the ''rectus abdominus''
**The ''External abdominal oblique'' runs caudoventrally from the lateral surface of the ribs and the lumbar fascia to the linea alba
**The ''Internal abdominal oblique'' runs cranioventrally from the tuber coxae and the thoracolumbar fascia to the linea alba
**The ''Transversus abdominus'' is the deepest muscle of the flank, running dorsoventrally from the inner surface of the last ribs and the transverse processes of the lumbar vertebrae
**The ''Rectus abdominus'' forms a broad band parallel to the linea alba, arising from the ventral costal cartilages and inserting on the prepubic tendon
*Sublumbar Muscles:
**''Psoas minor'': stabilizer of the vertebral column, may also rotate the pelvis at the sacroiliac joint
**''Psoas major'' and ''Iliacus'':

=Video Links=
*[http://stream2.rvc.ac.uk/Frean/Pony/abdominal_layers.wmv Abdominal Musculature, Pony Dissection, Copyright RVC 2008]
*[http://stream2.rvc.ac.uk/Frean/sheep/AbdominalWall.wmv Abdominal Wall, Sheep Dissection, Copyright RVC 2008]

Spinal Column - Anatomy & Physiology

2008-09-03T12:15:09Z

Katherine: /* Cervical Vertebrae */

{{toplink
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|linkpage =Musculoskeletal System - Anatomy & Physiology
|linktext =Musculoskeletal System
|maplink = Musculoskeletal System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
[[Image:Anatomy_and_physiology_of_animals_Regions_of_a_vertebral_column.jpg|thumb|right|250px|Divisions of the spinal cord- Copyright Ruth Lawson Otago Polytechnic ]]

=''Divisions and Landmarks''=
The common pattern of canine landmarks, according to Dyce, Sack, et al, can be quantified as such:
[[Image:Spinal landmarks.jpg|center|500px|Spinal Landmarks - Copyright Becky Pocock 2008]]

=''Vertebrae and Joints''=
[[Image:Cervical Vertebra.png|thumb|right|150px|Cervical Vertebra - Wikimedia Commons 2008]]
*Vertebrae consist of a body which encloses the vertebral foramen (through which the spinal cord and meninges run), a spinous process, and a transverse process, as well as articular processes by which they join together
*The form of the spinous process varies with respect to species and region

==Cervical Vertebrae==
*The first two cervical vertebrae are known as the '''atlas''' and the '''axis''' respectively, and are modified to allow movement of the head
**The atlas has no conventional body: instead it is composed of two lateral masses joined by dorsal and ventral arches
**The atlas and axis are fused in embryonic life
**The '''wing of the atlas''' is the transverse process of this vertebra and allows the spinal column to articulate with the skull by providing a resting place for the occipital condyles
**The axis is the longest vertebra
**The '''nuchal ligament''' connects the spinous process of the axis to the spinous process of the first thoracic vertebra (T1)
*The last (C7) cervical vertebra has a taller spinous process than those proceeding it, and articulates with the first pair of ribs

==Thoracic Vertebrae==
*Thoracic vertebrae articulate with the ribs
*They are distingushed by short bodies with flattened extremities, costal facets, short transverse processes, and prominent spinous processes
*They reach a maximum height a few vertebrae behind the cervicothoracic junction (constituting the '''withers''' of the horse) and then decline
*The orientation of spinous processes shifts from caudo- to craniodorsal

==Lumbar Vertebrae==
*Longer and more uniform in shape than thoracic vertebrae
*Shorter in height, with long, flattened transverse processes that project laterally

==Sacral Vertebrae==
*'''Sacrum''': a single bone formed by the fusion of several vertebrae that articulates with the pelvic girdle
*Allows the thrust of the hindlimbs to be transmitted to the trunk
*Narrows caudally and is curved to present a concave surface to the pelvic cavity

==Caudal Vertebrae==
*Number varies greatly even within species
*Progressive simplification of form

==Joints of the Spinal Column==
*Two types of joints:
**Cartilaginous: direct connections between vertebral bodies
***Bodies of adjacent vertebrae connected by thick, flexible intervertebral discs, consisting of two parts:
****'''Nucleus pulposus''': slightly eccentric, notochord derivative, contained under pressure and prone to escape
****'''Annulus fibrosis''': encircling bundles of fibrous tissue that pass obliquely from one vertebra to another, with changing orientation
**Synovial: between facets on vertebral arches
*Modified in the regions of the head and pelvis
**Joints of the atlas:
***'''Atlanto-occipital joint''': between condyles of the skull and corresponding cavities of the atlas
****Functions as a ginglymus: movement is restricted to flexion/extension in the sagittal plane (eg nodding)
***'''Atlantoaxial joint''': ventral arch of atlas and the body of the axis face into a single synovial cavity with limited areas of contact
****Movement is rotational about a longitudinal axis (eg. head shaking)

=''Spinal Cord''=

=''Hypaxial and Epaxial Muscles''=
[[Image: epaxial muscles.JPG|thumb|right|150px|Epaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]
[[Image: hypaxial muscles.JPG|thumb|right|150px|Hypaxial muscles- Copyright C. Clarkson and T.F. Fletcher, University of Minnesota]]
*'''Epaxial muscles''': extensors of the vertebral column
**Dorsal to the line of the transverse processes of the vertebrae
**Innervation comes from the dorsal branches of the spinal nerves
**Rarely of clinical importance
**Arranged in three parallel columns
***Lateral column: ''Iliocostalis'' arises from the ilium and transverse processes of the lumbar vertebrae to insert on cranial lumbar vertebrae and ribs, spanning about 4 vertebrae
***Middle column: ''Longissimus''; strongest, extending from the ilium and sacrum to the head and neck
***Medial column: ''Transversospinalis''; most complex, lying between medial vertebral arches and spinous processes
*'''Hypaxial Muscles''': flexors of the neck and tail
**''Longus colli'': from cranial thoracic region to the atlas, covering ventral vertebral bodies
**''Rectus capitis ventralis'': atlas to ventral skull
**''Longus capitis'': midcervical vertebrae to skull
**''Scalenus'' muscles: caudal cervica vertebrae to first few ribs, which they stabilize on inspiration

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Muscles - Anatomy & Physiology

2008-08-29T14:21:03Z

Katherine: /* Smooth Muscle */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

==Introduction==
Muscle mass accounts for a large majority of the carcass weight of domestic animals. Muscular contraction is necessary for voluntary and involuntary movement of limbs, stabilization of joints, maintaining luminal diameter (in the case of arteries, bowel, etc), and to produce heat. The number of muscle fibers an individual possesses is determined by genetics and is set at birth, although muscle size and type (i.e. glycolytic to oxidative and vice versa) can be altered. Further muscle development therefore occurs by hypertrophy, rather than hyperplasia of muscle fibers. Three types of muscle can be described:
*Skeletal (also referred to as Striated, Somatic, Voluntary)
*Smooth (also referred to as Visceral)
*Cardiac

==Skeletal Muscle==
[[Image:Striated Muscle 1.jpg|thumb|right|150px|Striated muscle - Copyright RVC 2008]]
[[Image:muscle.jpg|thumb|right|150px|Triad Junction - Copyright RVC 2008]]
*Each muscle '''belly''' is composed of multiple '''fascicles''', each of which consists of a bundle of muscle '''fibers'''
*Muscle "fiber" means a single cell, which is multi-nucleate, and known as '''syncitia'''
**'''Parallel''' fibers: running from origin to insertion)
***Long fibers allow for a faster contraction and a greater range of motion
**'''Pennate''' fibers: at an angle to line of pull of an internal tendon or aponeurosis
***Short fibers allow for a greater force capacity
*Within each fiber are groups of parallel, longitudinal myofibrils
**Myofibrils are arranged as '''sarcomeres''', bound by Z-discs, which are the functional unit of muscle contraction
**Each sarcomere contains 2 separate groups of myofilaments:
***Thin filament, containing '''Actin''', located centrally
***Thick filament, containing '''Myosin''', originating from either side of each Z-disc
*Two basic types of skeletal myofibre:
**'''Primary: Oxidative'''
***Grossly '''red'''
***'''High''' myoglobin level
***'''Slow''' rate of contraction
***High '''oxidative''' activity
***Function - postural, sustained activity
**'''Secondary: Glycolytic'''
***Grossly '''white'''
***'''Low''' myoglobin level
***'''Fast''' rate of contraction
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
**Each muscle fiber is controlled by a single motor neuron
**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
**Depolarization of the sarcoplasmic reticulum causes Calcium to be released, which activates muscle contraction
***Muscle contraction occurs when (thin) Actin filaments slide past (thick) Myosin filaments
***Myosin heads bind Actin subunits, forming cross-bridges, hydrolyzing ATP and providing energy for contraction
***Myosin heads undergo power stroke, displacing Actin and releasing ADP and Pi
*Control of skeletal muscle activity is regulated by the '''thin filament'''
**In the off state, tropomyosin coiled-coils block the helical grooves of the actin filament
**Tropomyosin movement relieves the steric block, allowing access to myosin binding sites
***Calcium regulates muscle contraction by binding troponin-C, which is attached to the thin filament
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
*Types of Muscle Contraction:
**'''Concentric''': muscle shortens and bones are brought closer together
**'''Isometric''': muscle is active but does not change in length (force without motion)
**'''Eccentric''': muscle is active while lengthening

==Smooth Muscle==
[[Image:Smooth Muscle 1.jpg|thumb|right|150px|Smooth muscle - Copyright RVC 2008]]
*Slower contraction and relaxation
**Undeveloped sarcoplasmic reticulum means that smooth muscle depends on the plasmalemma release of Ca: affects contractile properties
*Smooth muscle lacks troponin
*Control of smooth muscle contraction involves '''thin and thick filament regulation'''
*Thin filament regulation is carried out by the actin binding protein, '''Caldesmon''', which binds the thin filament and blocks myosin access
**'''Calmodulin''' (activated by binding Ca) binds caldesmon and causes its dissociation from actin, enabling contraction
*Thick filament regulation occurs by the '''phosphorylation''' of the '''regulatory light chain (RLC)'''
**Calmodulin-Ca binds and activates myosin light chain kinase (MLCK)
**MLCK then phosphorylates RLC, turning myosin on
**Myosin light chain phosphatase (MLCP) switches myosin off
*'''Single Unit''': myogenic contraction; depolarized by gap junctions; eg. intestinal smooth muscle
*'''Multi-unit''': neurogenic contraction; no gap junctions; eg. iris

==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase

==Tendon==
[[Image:Tendon micro structure.jpg|right|thumb|150px|Histology of tendon Copyright RVC 2008]]
*Connective tissue point of attachment between muscle and bone
*Consists of dense collagen type 1 fibres and fibroblasts (tenocytes)
*Possess great tensile strength
*Highly elastic: important in absorbing and storing energy
**Elastic recoil provides a crucial role in locomotion
*Can be protected by sesamoid bones at a point of angulation over bony surface
*Fluid-filled bursae provide cushioning and protection where necessary
**Walls and sheaths resemble synovial joint components

==Links==
*[[Muscles - Pathology|Muscle Pathology]]
*[[Bursae and Tendons - Pathology|Bursae and Tendons Pathology]]

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Muscles - Anatomy & Physiology

2008-08-29T14:01:08Z

Katherine: /* Skeletal Muscle */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

==Introduction==
Muscle mass accounts for a large majority of the carcass weight of domestic animals. Muscular contraction is necessary for voluntary and involuntary movement of limbs, stabilization of joints, maintaining luminal diameter (in the case of arteries, bowel, etc), and to produce heat. The number of muscle fibers an individual possesses is determined by genetics and is set at birth, although muscle size and type (i.e. glycolytic to oxidative and vice versa) can be altered. Further muscle development therefore occurs by hypertrophy, rather than hyperplasia of muscle fibers. Three types of muscle can be described:
*Skeletal (also referred to as Striated, Somatic, Voluntary)
*Smooth (also referred to as Visceral)
*Cardiac

==Skeletal Muscle==
[[Image:Striated Muscle 1.jpg|thumb|right|150px|Striated muscle - Copyright RVC 2008]]
[[Image:muscle.jpg|thumb|right|150px|Triad Junction - Copyright RVC 2008]]
*Each muscle '''belly''' is composed of multiple '''fascicles''', each of which consists of a bundle of muscle '''fibers'''
*Muscle "fiber" means a single cell, which is multi-nucleate, and known as '''syncitia'''
**'''Parallel''' fibers: running from origin to insertion)
***Long fibers allow for a faster contraction and a greater range of motion
**'''Pennate''' fibers: at an angle to line of pull of an internal tendon or aponeurosis
***Short fibers allow for a greater force capacity
*Within each fiber are groups of parallel, longitudinal myofibrils
**Myofibrils are arranged as '''sarcomeres''', bound by Z-discs, which are the functional unit of muscle contraction
**Each sarcomere contains 2 separate groups of myofilaments:
***Thin filament, containing '''Actin''', located centrally
***Thick filament, containing '''Myosin''', originating from either side of each Z-disc
*Two basic types of skeletal myofibre:
**'''Primary: Oxidative'''
***Grossly '''red'''
***'''High''' myoglobin level
***'''Slow''' rate of contraction
***High '''oxidative''' activity
***Function - postural, sustained activity
**'''Secondary: Glycolytic'''
***Grossly '''white'''
***'''Low''' myoglobin level
***'''Fast''' rate of contraction
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
**Each muscle fiber is controlled by a single motor neuron
**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
**Depolarization of the sarcoplasmic reticulum causes Calcium to be released, which activates muscle contraction
***Muscle contraction occurs when (thin) Actin filaments slide past (thick) Myosin filaments
***Myosin heads bind Actin subunits, forming cross-bridges, hydrolyzing ATP and providing energy for contraction
***Myosin heads undergo power stroke, displacing Actin and releasing ADP and Pi
*Control of skeletal muscle activity is regulated by the '''thin filament'''
**In the off state, tropomyosin coiled-coils block the helical grooves of the actin filament
**Tropomyosin movement relieves the steric block, allowing access to myosin binding sites
***Calcium regulates muscle contraction by binding troponin-C, which is attached to the thin filament
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
*Types of Muscle Contraction:
**'''Concentric''': muscle shortens and bones are brought closer together
**'''Isometric''': muscle is active but does not change in length (force without motion)
**'''Eccentric''': muscle is active while lengthening

==Smooth Muscle==
[[Image:Smooth Muscle 1.jpg|thumb|right|150px|Smooth muscle - Copyright RVC 2008]]
*Slower contraction and relaxation
**Undeveloped sarcoplasmic reticulum means that smooth muscle depends on the plasmalemma release of Ca: affects contractile prpperties
*Smooth muscle lacks troponin
*Control of smooth muscle contraction involves '''thin and thick filament regulation'''
*Thin filament regulation is carried out by the actin binding protein, '''Caldesmon''', which binds the thin filament and blocks myosin access
**'''Calmodulin''' (activated by binding Ca) binds caldesmon and causes its dissociation from actin, enabling contraction
*Thick filament regulation occurs by the '''phosphorylation''' of the '''regulatory light chain (RLC)'''
**Calmodulin-Ca binds and activates myosin light chain kinase (MLCK)
**MLCK then phosphorylates RLC, turning myosin on
**Myosin light chain phosphatase (MLCP) switches myosin off
*'''Single Unit''': myogenic contraction; depolarized by gap junctions; eg. intestinal smooth muscle
*'''Multi-unit''': neurogenic contraction; no gap junctions; eg. iris

==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase

==Tendon==
[[Image:Tendon micro structure.jpg|right|thumb|150px|Histology of tendon Copyright RVC 2008]]
*Connective tissue point of attachment between muscle and bone
*Consists of dense collagen type 1 fibres and fibroblasts (tenocytes)
*Possess great tensile strength
*Highly elastic: important in absorbing and storing energy
**Elastic recoil provides a crucial role in locomotion
*Can be protected by sesamoid bones at a point of angulation over bony surface
*Fluid-filled bursae provide cushioning and protection where necessary
**Walls and sheaths resemble synovial joint components

==Links==
*[[Muscles - Pathology|Muscle Pathology]]
*[[Bursae and Tendons - Pathology|Bursae and Tendons Pathology]]

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Muscles - Anatomy & Physiology

2008-08-29T13:58:53Z

Katherine: /* Skeletal Muscle */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

==Introduction==
Muscle mass accounts for a large majority of the carcass weight of domestic animals. Muscular contraction is necessary for voluntary and involuntary movement of limbs, stabilization of joints, maintaining luminal diameter (in the case of arteries, bowel, etc), and to produce heat. The number of muscle fibers an individual possesses is determined by genetics and is set at birth, although muscle size and type (i.e. glycolytic to oxidative and vice versa) can be altered. Further muscle development therefore occurs by hypertrophy, rather than hyperplasia of muscle fibers. Three types of muscle can be described:
*Skeletal (also referred to as Striated, Somatic, Voluntary)
*Smooth (also referred to as Visceral)
*Cardiac

==Skeletal Muscle==
[[Image:Striated Muscle 1.jpg|thumb|right|150px|Striated muscle - Copyright RVC 2008]]
[[Image:muscle.jpg|thumb|right|150px|Triad Junction - Copyright RVC 2008]]
*Each muscle '''belly''' is composed of multiple '''fascicles''', each of which consists of a bundle of muscle '''fibers'''
*Muscle "fiber" means a single cell, which is multi-nucleate, and known as '''syncitia'''
**'''Parallel''' fibers: running from origin to insertion)
***Long fibers allow for a faster contraction and a greater range of motion
**'''Pennate''' fibers: at an angle to line of pull off an internal tendon or aponeurosis
***Short fibers allow for a greater force capacity
*Within each fiber are groups of parallel, longitudinal myofibrils
**Myofibrils are arranged as '''sarcomeres''', bound by Z-discs, which are the functional unit of muscle contraction
**Each sarcomere contains 2 separate groups of myofilaments:
***Thin filament, containing '''Actin''', located centrally
***Thick filament, containing '''Myosin''', originating from either side of each Z-disc
*Two basic types of skeletal myofibre:
**'''Primary: Oxidative'''
***Grossly '''red'''
***'''High''' myoglobin level
***'''Slow''' rate of contraction
***High '''oxidative''' activity
***Function - postural, sustained activity
**'''Secondary: Glycolytic'''
***Grossly '''white'''
***'''Low''' myoglobin level
***'''Fast''' rate of contraction
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
**Each muscle fiber is controlled by a single motor neuron
**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
**Depolarization of the sarcoplasmic reticulum causes Calcium to be released, which activates muscle contraction
***Muscle contraction occurs when (thin) Actin filaments slide past (thick) Myosin filaments
***Myosin heads bind Actin subunits, forming cross-bridges, hydrolyzing ATP and providing energy for contraction
***Myosin heads undergo power stroke, displacing Actin and releasing ADP and Pi
*Control of skeletal muscle activity is regulated by the '''thin filament'''
**In the off state, tropomyosin coiled-coils block the helical grooves of the actin filament
**Tropomyosin movement relieves the steric block, allowing access to myosin binding sites
***Calcium regulates muscle contraction by binding troponin-C, which is attached to the thin filament
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
*Types of Muscle Contraction:
**'''Concentric''': muscle shortens and bones are brought closer together
**'''Isometric''': muscle is active but does not change in length (force without motion)
**'''Eccentric''': muscle is active while lengthening

==Smooth Muscle==
[[Image:Smooth Muscle 1.jpg|thumb|right|150px|Smooth muscle - Copyright RVC 2008]]
*Slower contraction and relaxation
**Undeveloped sarcoplasmic reticulum means that smooth muscle depends on the plasmalemma release of Ca: affects contractile prpperties
*Smooth muscle lacks troponin
*Control of smooth muscle contraction involves '''thin and thick filament regulation'''
*Thin filament regulation is carried out by the actin binding protein, '''Caldesmon''', which binds the thin filament and blocks myosin access
**'''Calmodulin''' (activated by binding Ca) binds caldesmon and causes its dissociation from actin, enabling contraction
*Thick filament regulation occurs by the '''phosphorylation''' of the '''regulatory light chain (RLC)'''
**Calmodulin-Ca binds and activates myosin light chain kinase (MLCK)
**MLCK then phosphorylates RLC, turning myosin on
**Myosin light chain phosphatase (MLCP) switches myosin off
*'''Single Unit''': myogenic contraction; depolarized by gap junctions; eg. intestinal smooth muscle
*'''Multi-unit''': neurogenic contraction; no gap junctions; eg. iris

==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase

==Tendon==
[[Image:Tendon micro structure.jpg|right|thumb|150px|Histology of tendon Copyright RVC 2008]]
*Connective tissue point of attachment between muscle and bone
*Consists of dense collagen type 1 fibres and fibroblasts (tenocytes)
*Possess great tensile strength
*Highly elastic: important in absorbing and storing energy
**Elastic recoil provides a crucial role in locomotion
*Can be protected by sesamoid bones at a point of angulation over bony surface
*Fluid-filled bursae provide cushioning and protection where necessary
**Walls and sheaths resemble synovial joint components

==Links==
*[[Muscles - Pathology|Muscle Pathology]]
*[[Bursae and Tendons - Pathology|Bursae and Tendons Pathology]]

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Muscles - Anatomy & Physiology

2008-08-29T13:58:14Z

Katherine: /* Introduction */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

==Introduction==
Muscle mass accounts for a large majority of the carcass weight of domestic animals. Muscular contraction is necessary for voluntary and involuntary movement of limbs, stabilization of joints, maintaining luminal diameter (in the case of arteries, bowel, etc), and to produce heat. The number of muscle fibers an individual possesses is determined by genetics and is set at birth, although muscle size and type (i.e. glycolytic to oxidative and vice versa) can be altered. Further muscle development therefore occurs by hypertrophy, rather than hyperplasia of muscle fibers. Three types of muscle can be described:
*Skeletal (also referred to as Striated, Somatic, Voluntary)
*Smooth (also referred to as Visceral)
*Cardiac

==Skeletal Muscle==
[[Image:Striated Muscle 1.jpg|thumb|right|150px|Striated muscle - Copyright RVC 2008]]
[[Image:muscle.jpg|thumb|right|150px|Triad Junction - Copyright RVC 2008]]
*Each muscle '''belly''' is composed of multiple '''fascicles''', each of which consists of a bundle of muscle '''fibers'''
*Muscle "fiber" means a single cell, which are multi-nucleate, and known as '''syncitia'''
**'''Parallel''' fibers: running from origin to insertion)
***Long fibers allow for a faster contraction and a greater range of motion
**'''Pennate''' fibers: at an angle to line of pull off an internal tendon or aponeurosis
***Short fibers allow for a greater force capacity
*Within each fiber are groups of parallel, longitudinal myofibrils
**Myofibrils are arranged as '''sarcomeres''', bound by Z-discs, which are the functional unit of muscle contraction
**Each sarcomere contains 2 separate groups of myofilaments:
***Thin filament, containing '''Actin''', located centrally
***Thick filament, containing '''Myosin''', originating from either side of each Z-disc
*Two basic types of skeletal myofibre:
**'''Primary: Oxidative'''
***Grossly '''red'''
***'''High''' myoglobin level
***'''Slow''' rate of contraction
***High '''oxidative''' activity
***Function - postural, sustained activity
**'''Secondary: Glycolytic'''
***Grossly '''white'''
***'''Low''' myoglobin level
***'''Fast''' rate of contraction
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
**Each muscle fiber is controlled by a single motor neuron
**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
**Depolarization of the sarcoplasmic reticulum causes Calcium to be released, which activates muscle contraction
***Muscle contraction occurs when (thin) Actin filaments slide past (thick) Myosin filaments
***Myosin heads bind Actin subunits, forming cross-bridges, hydrolyzing ATP and providing energy for contraction
***Myosin heads undergo power stroke, displacing Actin and releasing ADP and Pi
*Control of skeletal muscle activity is regulated by the '''thin filament'''
**In the off state, tropomyosin coiled-coils block the helical grooves of the actin filament
**Tropomyosin movement relieves the steric block, allowing access to myosin binding sites
***Calcium regulates muscle contraction by binding troponin-C, which is attached to the thin filament
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
*Types of Muscle Contraction:
**'''Concentric''': muscle shortens and bones are brought closer together
**'''Isometric''': muscle is active but does not change in length (force without motion)
**'''Eccentric''': muscle is active while lengthening

==Smooth Muscle==
[[Image:Smooth Muscle 1.jpg|thumb|right|150px|Smooth muscle - Copyright RVC 2008]]
*Slower contraction and relaxation
**Undeveloped sarcoplasmic reticulum means that smooth muscle depends on the plasmalemma release of Ca: affects contractile prpperties
*Smooth muscle lacks troponin
*Control of smooth muscle contraction involves '''thin and thick filament regulation'''
*Thin filament regulation is carried out by the actin binding protein, '''Caldesmon''', which binds the thin filament and blocks myosin access
**'''Calmodulin''' (activated by binding Ca) binds caldesmon and causes its dissociation from actin, enabling contraction
*Thick filament regulation occurs by the '''phosphorylation''' of the '''regulatory light chain (RLC)'''
**Calmodulin-Ca binds and activates myosin light chain kinase (MLCK)
**MLCK then phosphorylates RLC, turning myosin on
**Myosin light chain phosphatase (MLCP) switches myosin off
*'''Single Unit''': myogenic contraction; depolarized by gap junctions; eg. intestinal smooth muscle
*'''Multi-unit''': neurogenic contraction; no gap junctions; eg. iris

==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase

==Tendon==
[[Image:Tendon micro structure.jpg|right|thumb|150px|Histology of tendon Copyright RVC 2008]]
*Connective tissue point of attachment between muscle and bone
*Consists of dense collagen type 1 fibres and fibroblasts (tenocytes)
*Possess great tensile strength
*Highly elastic: important in absorbing and storing energy
**Elastic recoil provides a crucial role in locomotion
*Can be protected by sesamoid bones at a point of angulation over bony surface
*Fluid-filled bursae provide cushioning and protection where necessary
**Walls and sheaths resemble synovial joint components

==Links==
*[[Muscles - Pathology|Muscle Pathology]]
*[[Bursae and Tendons - Pathology|Bursae and Tendons Pathology]]

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Muscles - Anatomy & Physiology

2008-08-29T13:57:23Z

Katherine: /* Introduction */

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

==Introduction==
Muscle mass accounts for a large majority of the carcass weight of domestic animals. Muscular contraction is necessary for voluntary and involuntary movement of limbs, stabilization of joints, maintaining luminal diameter (in the case of arteries, bowel, etc), and to produce heat. The number of muscle fibers an individual possesses is determined by genetics and is set at birth, although muscle size and type (i.e. glycolytic to oxidative and vice versa) can be altered. Further muscle development therefore occurs by hypertrophy, rather than hyperplasia of muscle fibers. Three types of muscle can be described:
*Skeletal (Striated, Somatic, Voluntary)
*Smooth (Visceral)
*Cardiac

==Skeletal Muscle==
[[Image:Striated Muscle 1.jpg|thumb|right|150px|Striated muscle - Copyright RVC 2008]]
[[Image:muscle.jpg|thumb|right|150px|Triad Junction - Copyright RVC 2008]]
*Each muscle '''belly''' is composed of multiple '''fascicles''', each of which consists of a bundle of muscle '''fibers'''
*Muscle "fiber" means a single cell, which are multi-nucleate, and known as '''syncitia'''
**'''Parallel''' fibers: running from origin to insertion)
***Long fibers allow for a faster contraction and a greater range of motion
**'''Pennate''' fibers: at an angle to line of pull off an internal tendon or aponeurosis
***Short fibers allow for a greater force capacity
*Within each fiber are groups of parallel, longitudinal myofibrils
**Myofibrils are arranged as '''sarcomeres''', bound by Z-discs, which are the functional unit of muscle contraction
**Each sarcomere contains 2 separate groups of myofilaments:
***Thin filament, containing '''Actin''', located centrally
***Thick filament, containing '''Myosin''', originating from either side of each Z-disc
*Two basic types of skeletal myofibre:
**'''Primary: Oxidative'''
***Grossly '''red'''
***'''High''' myoglobin level
***'''Slow''' rate of contraction
***High '''oxidative''' activity
***Function - postural, sustained activity
**'''Secondary: Glycolytic'''
***Grossly '''white'''
***'''Low''' myoglobin level
***'''Fast''' rate of contraction
***High '''glycolytic''' activity
***Function - exercise, bursts of activity
*'''Neurogenic Contraction''': Muscle activation is initiated by a nervous impulse crossing the Neuromuscular Junction
**Each muscle fiber is controlled by a single motor neuron
**The neurotransmitter, '''Acetylcholine (Ach)''', binds receptors in the muscle fiber to open Na+ channels
**This causes a wave of depolarization along the sarcoplasmic membrane, further opening voltage-gated Na+ channels, which propagates the signal along the sarcolemma
**Depolarization of the sarcoplasmic reticulum causes Calcium to be released, which activates muscle contraction
***Muscle contraction occurs when (thin) Actin filaments slide past (thick) Myosin filaments
***Myosin heads bind Actin subunits, forming cross-bridges, hydrolyzing ATP and providing energy for contraction
***Myosin heads undergo power stroke, displacing Actin and releasing ADP and Pi
*Control of skeletal muscle activity is regulated by the '''thin filament'''
**In the off state, tropomyosin coiled-coils block the helical grooves of the actin filament
**Tropomyosin movement relieves the steric block, allowing access to myosin binding sites
***Calcium regulates muscle contraction by binding troponin-C, which is attached to the thin filament
***This causes inhibition of the steric block keeping Actin and Myosin from interacting
*Increased Calcium causes a negative feedback inhibition of Ca release, and it is pumped back into the sarcoplasmic reticulum by the Ca/ATPase pump
*Types of Muscle Contraction:
**'''Concentric''': muscle shortens and bones are brought closer together
**'''Isometric''': muscle is active but does not change in length (force without motion)
**'''Eccentric''': muscle is active while lengthening

==Smooth Muscle==
[[Image:Smooth Muscle 1.jpg|thumb|right|150px|Smooth muscle - Copyright RVC 2008]]
*Slower contraction and relaxation
**Undeveloped sarcoplasmic reticulum means that smooth muscle depends on the plasmalemma release of Ca: affects contractile prpperties
*Smooth muscle lacks troponin
*Control of smooth muscle contraction involves '''thin and thick filament regulation'''
*Thin filament regulation is carried out by the actin binding protein, '''Caldesmon''', which binds the thin filament and blocks myosin access
**'''Calmodulin''' (activated by binding Ca) binds caldesmon and causes its dissociation from actin, enabling contraction
*Thick filament regulation occurs by the '''phosphorylation''' of the '''regulatory light chain (RLC)'''
**Calmodulin-Ca binds and activates myosin light chain kinase (MLCK)
**MLCK then phosphorylates RLC, turning myosin on
**Myosin light chain phosphatase (MLCP) switches myosin off
*'''Single Unit''': myogenic contraction; depolarized by gap junctions; eg. intestinal smooth muscle
*'''Multi-unit''': neurogenic contraction; no gap junctions; eg. iris

==Cardiac Muscle==
*Structural: striated but uninucleate, highly vascularized
*Gap junctions concentrated at intercalated discs
**'''Myogenic Contraction''' spreads cell to cell and does not depend on nervous imput to individual cells
**Areas of low electrical resistance allow rapid spread of action potentials
**Contraction is regulated by autonomic neurons and circulating hormones
*Contractile mechanism similar to skeletal muscle: increase cytosolic Ca
**Ca influx across plasma membrane AND sarcoplasmic reticulum
*Action potential has a prolonged plateau phase

==Tendon==
[[Image:Tendon micro structure.jpg|right|thumb|150px|Histology of tendon Copyright RVC 2008]]
*Connective tissue point of attachment between muscle and bone
*Consists of dense collagen type 1 fibres and fibroblasts (tenocytes)
*Possess great tensile strength
*Highly elastic: important in absorbing and storing energy
**Elastic recoil provides a crucial role in locomotion
*Can be protected by sesamoid bones at a point of angulation over bony surface
*Fluid-filled bursae provide cushioning and protection where necessary
**Walls and sheaths resemble synovial joint components

==Links==
*[[Muscles - Pathology|Muscle Pathology]]
*[[Bursae and Tendons - Pathology|Bursae and Tendons Pathology]]

<big><center>[[Musculoskeletal System - Anatomy & Physiology|'''BACK TO MUSCULOSKELETAL ANATOMY AND PHYSIOLOGY''']]</center></big>

Endocrine System Overview - Anatomy & Physiology

2008-08-28T17:40:57Z

Katherine: /* The Endocrine System */

{{toplink
|linkpage =Anatomy and Physiology
|linktext =ANATOMY & PHYSIOLOGY
|thispagenormal = Endocrine System - Anatomy & Physiology
|thispagemap = Endocrine System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
==The Endocrine System==

Comprised of a group of duct-less [[Endocrine System - Endocrine Glands - Anatomy & Physiology|glands]] with limited or no anatomical contact with each other, the Endocrine System integrates and controls metabolic activity through the secretion of [[Endocrine System - Hormones - Anatomy & Physiology|hormones]] into the [[Vascular System - Anatomy & Physiology|vascular system]]. These hormones may have their effects on tissues and organs far from where they were produced.

The endocrine system integrates with, and is under the control of the [[Nervous and Special Senses - Anatomy & Physiology#Nervous System|Nervous System]] with close association between the [[Endocrine System - Hypothalamus - Anatomy & Physiology|Hypothalamus]] and the [[Endocrine System - Pituitary Gland - Anatomy & Physiology|Pituitary Gland]], which acts to co-ordinate many of the body's other endocrine glands. The system relies largely on [[Endocrine System - Negative Feedback - Anatomy & Physiology|negative feedback]] loops to maintain homeostasis, with some examples of [[Endocrine System - Positive Feedback - Anatomy & Physiology|positive feedback]] to elicit suitable responses.

Many of the endocrine glands have a similar basic structure, composed of clusters of secretory cells of epithelial origin. Hormones are secreted into the interstitial space whereby they are rapidly absorbed into the [[Vascular System - Anatomy & Physiology|vascular system]]. In contrast the [[Exocrine - Anatomy & Physiology|exocrine]] system utilises ducts enabling it to secrete its contents directly to its target area.

Here we will consider the main endocrine glands and their functional anatomy and physiology:

<big>
::[[Endocrine System - Hypothalamus - Anatomy & Physiology|Hypothalamus]]

::[[Endocrine System - Pituitary Gland - Anatomy & Physiology|Pituitary Gland]]

::[[Endocrine System - Thyroid Gland - Anatomy & Physiology|Thyroid Gland]]

::[[Endocrine System - Parathyroid Glands - Anatomy & Physiology|Parathyroid Glands]]

::[[Endocrine System - Adrenal Glands - Anatomy & Physiology|Adrenal Glands]]

::[[Endocrine System - Pineal Gland - Anatomy & Physiology|Pineal Gland]]
</big>

Endocrine functions of the following tissues and organs will be briefly covered:

::[[Endocrine System - Endocrine Pancreas - Anatomy & Physiology|Pancreas]]

::[[Endocrine System - Gut - Anatomy & Physiology|Gut]]

::[[Endocrine System - Kidney - Anatomy & Physiology|Kidney]]

::[[Endocrine System - Heart - Anatomy & Physiology|Heart]]

::[[Endocrine System - Adipose Tissue - Anatomy & Physiology|Adipose Tissue]]

::[[Endocrine System - Liver - Anatomy & Physiology|Liver]]

::[[Endocrine System - Skin - Anatomy & Physiology|Skin]]

::[[Thymus - Anatomy & Physiology#Endocrine|Thymus]]

::[[Endocrine System - Testes - Anatomy & Physiology|Testes]]

::[[Endocrine System - Ovaries - Anatomy & Physiology|Ovaries]]

::[[Endocrine System - Placenta - Anatomy & Physiology|Placenta]]

Also mentioned are the main hormonally controlled homeostatic mechanisms for ions:
<big>
::[[Endocrine System - Calcium Homeostasis - Anatomy & Physiology|Calcium Homeostasis]]

::[[Endocrine System - Phosphorus Homeostasis - Anatomy & Physiology|Phosphorus Homeostasis]]

::[[Endocrine System - Magnesium - Anatomy & Physiology|Magnesium]]

</big>

==Test Yourself on Endocrinology - Anatomy and Physiology==

*[[Endocrine System - Flash Cards - Anatomy and Physiology|Flash Cards]]

==Acknowledgements and Reference Material==

[[Endocrine System - Acknowledgements - Anatomy & Physiology|Acknowledgements]]

[[Endocrine System - Reference Material - Anatomy & Physiology|Reference Material]]

Cardiorespiratory System Overview - Anatomy & Physiology

2008-08-28T17:05:48Z

Katherine: /* Cardiovascular System */

{{toplink
|linkpage =Anatomy and Physiology
|linktext =ANATOMY & PHYSIOLOGY
|thispagenormal = Cardiorespiratory System - Anatomy & Physiology
|thispagemap = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Overview of the Cardiorespiratory System==

===Introduction===

The mammalian cardiovascular and respiratory systems have evolved primarily to provide the tissues of the body with oxygen and to remove carbon dioxide. The cardiorespiratory system also has metabolic and heat exchange roles.

===Respiratory System===

Air is [[Ventilation - Anatomy & Physiology|inhaled]] and passes through the upper respiratory tract (nares, [[Nasal cavity - Anatomy & Physiology|nasal cavity]], [[Nasopharynx - Anatomy & Physiology|nasopharynx]], [[Larynx - Anatomy & Physiology|larynx]], [[Trachea - Anatomy & Physiology|trachea]]) where it is heated and moistened. It then passes to the lower respiratory tract ([[Bronchi and bronchioles - Anatomy & Physiology|bronchi, bronchioles]], [[Lungs - Anatomy & Physiology|alveoli]]) where oxygen diffuses across the alveolar wall and into the blood, forming oxyhaemoglobin.

===Cardiovascular System===

Blood, which has been oxygenated by the [[Lungs - Anatomy & Physiology|lungs]], flows through the pulmonary vein to the left atrium of the heart and subsequently to the left ventricle from which it is ejected by the heart during ventricular systole. Oxygenated blood is then distributed to the different parts of the body via the aorta. The distribution of blood is controlled by vascular tone which dictates the degree of perfusion of capillary beds and therefore the amount of oxygen available to the various tissues. Carbon dioxide produced from cellular respiration is removed from the tissues and transported either attached to proteins, in solution or as bicarbonate via the venous system to the vena cavae and ultimately to the right atrium. The passage of venous blood is a product of blood flow, vascular valves and muscular and respiratory function. Carbon dioxide rich blood enters the right ventricle and is then pumped to the lungs via the pulmonary artery.

===Integration===

The function of the cardiac and respiratory systems are tightly linked and regulated to maintain blood pressure, tissue oxygen delivery and carbon dioxide removal. Cardiac function is controlled by baroreceptors (pressure receptors) which result in changes to the heart rate, contractility and vascular tone. Respiratory function is controlled centrally by chemoreceptors to maintain rate and both centrally and locally to maintain bronchiolar tone.

'''ANATOMY & PHYSIOLOGY OF:'''

[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|250px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
==Upper Respiratory Tract==

<big>'''[[Nasal cavity - Anatomy & Physiology|Nasal Cavity]]</big>

<big>'''[[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]]</big>

<big>'''[[Pharynx - Anatomy & Physiology|Pharynx]]</big>

<big>'''[[Guttural pouches - Anatomy & Physiology|Guttural Pouches]]</big>

<big>'''[[Larynx - Anatomy & Physiology|Larynx]] </big>

<big>'''[[Trachea - Anatomy & Physiology|Trachea]]</big>

==Lower Respiratory Tract==

<big>'''[[Bronchi and bronchioles - Anatomy & Physiology|Bronchi & Bronchioles]] </big>

<big>'''[[Lungs - Anatomy & Physiology|Lungs]]</big>

*[[Ventilation - Anatomy & Physiology|Ventilation]]
*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

<big>'''[[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity & Membranes]]</big>

==Cardiovascular System==

<big>'''[[Heart - Anatomy & Physiology|Heart]]</big>

<big>'''[[Vascular System - Anatomy & Physiology|Vascular System]]</big>

<big>'''[[References for the Cardiorespiratory system - Anatomy & Physiology| References for the Cardiorespiratory system]]</big>

Cardiorespiratory System Overview - Anatomy & Physiology

2008-08-28T17:05:19Z

Katherine: /* Cardiovascular System */

{{toplink
|linkpage =Anatomy and Physiology
|linktext =ANATOMY & PHYSIOLOGY
|thispagenormal = Cardiorespiratory System - Anatomy & Physiology
|thispagemap = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Overview of the Cardiorespiratory System==

===Introduction===

The mammalian cardiovascular and respiratory systems have evolved primarily to provide the tissues of the body with oxygen and to remove carbon dioxide. The cardiorespiratory system also has metabolic and heat exchange roles.

===Respiratory System===

Air is [[Ventilation - Anatomy & Physiology|inhaled]] and passes through the upper respiratory tract (nares, [[Nasal cavity - Anatomy & Physiology|nasal cavity]], [[Nasopharynx - Anatomy & Physiology|nasopharynx]], [[Larynx - Anatomy & Physiology|larynx]], [[Trachea - Anatomy & Physiology|trachea]]) where it is heated and moistened. It then passes to the lower respiratory tract ([[Bronchi and bronchioles - Anatomy & Physiology|bronchi, bronchioles]], [[Lungs - Anatomy & Physiology|alveoli]]) where oxygen diffuses across the alveolar wall and into the blood, forming oxyhaemoglobin.

===Cardiovascular System===

Blood, which has been oxygenated by the [[Lungs - Anatomy & Physiology|lungs]], flows through the pulmonary vein to the left atrium of the heart and subsequently to the left ventricle from which it is ejected by the heart during ventricular systole. Oxygenated blood is then distributed to the different parts of the body via the aorta. The distribution of blood is controlled by vascular tone which dictates the degree of perfusion of capillary beds and therefore the amount of oxygen available to the various tissues. Carbon dioxide produced from cellular respiration is removed from the tissues and transported either attached to proteins, in solution or as bicarbonate via the venous system to the vena cavae and ultimately to the right atrium. The passage of venous blood is a product of blood flow, vascular valves and muscular and respiratory function. Carbon dioxide rich blood enters the right ventricle and is then pumped to the lungs via the pulmonary artery.

===Integration===

The function of the cardiac and respiratory systems are tightly linked and regulated to maintain blood pressure, tissue oxygen delivery and carbon dioxide removal. Cardiac function is controlled by baroreceptors (pressure receptors) which result in changes to the heart rate, contractility and vascular tone. Respiratory function is controlled centrally by chemoreceptors to maintain rate and both centrally and locally to maintain bronchiolar tone.

'''ANATOMY & PHYSIOLOGY OF:'''

[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|250px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
==Upper Respiratory Tract==

<big>'''[[Nasal cavity - Anatomy & Physiology|Nasal Cavity]]</big>

<big>'''[[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]]</big>

<big>'''[[Pharynx - Anatomy & Physiology|Pharynx]]</big>

<big>'''[[Guttural pouches - Anatomy & Physiology|Guttural Pouches]]</big>

<big>'''[[Larynx - Anatomy & Physiology|Larynx]] </big>

<big>'''[[Trachea - Anatomy & Physiology|Trachea]]</big>

==Lower Respiratory Tract==

<big>'''[[Bronchi and bronchioles - Anatomy & Physiology|Bronchi & Bronchioles]] </big>

<big>'''[[Lungs - Anatomy & Physiology|Lungs]]</big>

*[[Ventilation - Anatomy & Physiology|Ventilation]]
*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

<big>'''[[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity & Membranes]]</big>

==Cardiovascular System==

<big>'''[[Heart - Anatomy & Physiology|Heart]]</big>

<big>'''[[Vascular System - Anatomy & Physiology|Vascular System]]</big>

<big>'''[References for the Cardiorespiratory system - Anatomy & Physiology| References for the Cardiorespiratory system]]</big>

Avian Liver - Anatomy & Physiology

2008-08-28T16:57:49Z

Katherine: /* Structure */

<big><center>[[Liver - Anatomy & Physiology|'''BACK TO THE LIVER - ANATOMY & PHYSIOLOGY''']]</center></big>
<big><center>[[Avian Digestive Tract - Anatomy & Physiology|'''BACK TO THE AVIAN DIGESTIVE TRACT - ANATOMY & PHYSIOLOGY''']]</center></big>

==Structure==

*2 lobes

*Dark brown coloured (except just after hatching where it is yellow)

*Right lobe larger than left lobe

*Ventral and caudal to the [[Heart - Anatomy & Physiology|heart]] (as there is no diaphragm)

*Closely associated to the [[The Proventriculus - Anatomy & Physiology|proventriculus]] and [[Spleen - Anatomy & Physiology|spleen]]

*Thin capsule

*Indistinct lobation

*2 bile ducts enter the distal [[Duodenum - Anatomy & Physiology|duodenum]], one from each lobe of the liver

*The duct from the right lobe is connected to the [[Gall Bladder - Anatomy & Physiology|gallbladder]]

*Hepatic lobules indistinct (except near hilus) due to a lack of perilobular connective tissue

*Avian bile aids the emulsification of fats and contains amylase and lipase
[[Image:Anatomy of the Avian Liver.jpg|thumb|right|150px|Anatomy of the Liver(Avian)- Copyright RVC 2008]]

==Function==

*See [[Liver - Anatomy & Physiology#Function|liver function]]

==Vasculature==

*See [[Liver - Anatomy & Physiology#Vasculature|liver vasculature]]

==Innervation==

*See [[Liver - Anatomy & Physiology#Innervation|liver innervation]]

==Lymphatics==

*See [[Liver - Anatomy & Physiology#Lymphatics|liver lymphatics]]

==Histology==
[[Image:Avian Liver and Spleen.jpg|thumb|right|150px|Liver and Spleen (Avian)- Copyright Nottingham 2008]]
*Polyhedral and angular cells

*Larger cells than in mammals

*Large, spherical nucleus

*Base of cell forms a wall of the sinusoid

*Cell apices communicate with the bile canaliculi

*Granular cytoplasm

*Liver cords form columns around the interlobular bile capillary. The cell arrangement is simpler than in mammals.

*Sinusoids anastamose freely

*Kupfer cells present

*Reticular fibres support the liver cords

*Elastic fibres in the capsule and vessels

==Species Differences==

*Pigeons and parrots lack a [[Gall Bladder - Anatomy & Physiology|gall bladder]]

==Links==

[[The Avian Alimentary Tract - Anatomy & Physiology - Flashcards|Avian Alimentary Tract Flashcards]]

[[Liver - Anatomy & Physiology]]

[[Gall Bladder - Anatomy & Physiology]]