WikiVet English - User contributions [en]

Canine Phalanges - Anatomy & Physiology

2013-03-21T21:45:26Z

JamiVet: /* Phalanges */

{{OpenPagesTop}}
==Introduction==

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 interchangeable 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 in that 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 of each articulates with it's corresponding carpal bone and the adjacent metacarpal. The distal end is its head, which is transversely cylindrical and articulates with the proximal phalanx. Metacarpals II - V possess a sagittal ridge on their palmar aspects.
 
 

====Phalanges====
The proximal phalanx of the main digits (II - V) have a concave articular surface and 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 separated by a groove. The middle phalanx is roughly two-thirds the length of the proximal phalanx and 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 phalanx. The distal phalanx is made up of a cone-shaped ungual process with a distinct collar called the 'ungual crest'. The deep ungual groove distal to the crest provides attachment for the proximal border of the claw and 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 first digit of the forelimb which is often mistaken as the dew claw is fully formed and functional. The true 'dew claw' (metacarpal I) which is found in the hind limb is not always present and comprises of nail, skin and connective tissue.

==Joints==
====Metacarpophalangeal Joint====
The metacarpophalangeal joint is able to undergo flexion and extension movements. Each joint (except the first digit) has a pair of sesamoid bones associated with the palmar aspect of the joint which articulate with a concave area of the proximal phalanx. The joint capsule runs between the four bones of the joint extending dorsally under the extensor tendon and part also intermingling 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. The '''collateral ligaments''' bind the the metacarpal bone to the proximal phalanx, with a deep branch attaching to the sesamoid bone. The '''palmar/intersesamoidean ligament''' is a mass of fibrocartilage that embeds the sesamoid bones. The palmar aspect of this ligament forms a groove for the deep flexor tendon to run in. The '''collateral sesamoid ligaments''' connect the outer aspect of the sesamoids to the proximal phalanx whilst the '''distal sesamoid ligaments''', although not well developed in the dog, connect the distal surface of the sesamoids to the palmar aspect of the phalanx. These ligaments 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 and 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====
The proximal interphalangeal joint provides flexion and extension movements. The joint capsule attaches near the articular surfaces of the proximal and middle phalanges and 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. The '''collateral ligaments''' connect the distal end of the proximal phalanx to the proximal end of the middle phalanx and lie in a vertical direction rather than along the bone axis.

====Distal Interphalangeal Joint====
The distal interphalangeal joint allows extension and slight flexion movements. The joint capsule attaches to the articular periphery of the bones and has a small fibrocartilagenous bead in the palmar aspect. The '''collateral ligaments''' connect the distal part of the middle phalanx to the sides of the ungual crest of the distal phalanx. The '''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'''
 
The function of the interosseous muscle is to support the metacarpophalangeal joints. It originates from the palmar aspect of the proximal end of the metacarpal bones and inserts on the sesamoid bones of the metacarpophalangeal joint, where it then continues as extensor branches that wrap round the dorsal aspect of the digit to join the extensor tendons.
 
 
====Forelimb====
The function of the '''superficial digital flexor''' is to facilitate flexion of the digits. It originates from the medial epicondyle of the humerus and inserts on the palmar aspect of the middle phalanges. The '''deep digital flexor''' muscle also allows flexion of the digits. It originates from the medial epicondyle of the humerus, proximal radius and ulna. It inserts on the palmar aspect of distal phalanges. The '''common digital extensor''' is an extensor of the digits and originates from the lateral epicondyle of the humerus. It inserts on the extensor process of the distal phalanx. The '''lateral digital extensor''' also allows extension of the digits. It originates from the lateral epicondyle of the humerus and inserts on the proximal phalanx.
 
 
====Hindlimb====
The '''long digital extensor''' muscle allows extension of the digits. It originates from the extensor fossa of the lateral femoral condyle and inserts in the 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. The '''lateral digital extensor''' also allows extension of the digits. It originates from the proximal fibula and lateral collateral ligament of the stifle. It joins to the tendon of the long digital extensor to insert on the distal phalanx of the 5th digit. The '''long extensor of the first digit''' muscle allows extension of the first phalanx. It originates from the proximal fibula and inserts on the metatarsophalangeal joint of the 2nd and 1st digit. The '''superficial digital flexor''' muscle provides digital flexion. It originates from the supracondylar tuberosity of the femur and is firmly united to the lateral head of the gastrocnemius. It inserts on the 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. The '''deep digital flexor''' muscle consists of three separate heads; the '''caudal tibial muscle''', the '''lateral digital flexor muscle''' and the '''medial digital flexor muscle''' which all facilitate flexion of the digits. The '''lateral digital flexor''' muscle originates on the caudal surface of the tibia and fibula and inserts by fusing with 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. The origin of the '''medial digital flexor''' is the head of the fibula and the popliteal line of the tibia. It inserts by fusing with the medial digital flexor tendon forming the deep flexor tendon. The '''caudal tibial''' muscle originates on the caudomedial surface of the tibia and the tendon then 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==
The canine paw is composed of four weight-bearing toes, each with a claw and footpad. In addition there is a metacarpal/metatarsal footpad.
 
 
====Footpad====
The epidermis of the footpad is thick, pigmented, keratinised and hairless. It is arranged into conical papillae with '''sweat/merocrine glands''' opening onto the surface of the footpad. 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 whilst the metacarpal/metatarsal pads are heart shaped, with the apex pointing distally and supporting the metacarpophalangeal joints. A small carpal pad is present medial and distal to the accessory carpal bone.
 
 
====Claw====
The claw 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, called the '''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'''. Papillae cover the dorsal aspect of the phalanx and contain the '''germinative layer''' which is the flat keratinised epidermal cells which are considered responsible for horn formation. The lateral and medial walls are formed by dermal laminae, rather than the papillae. The plantar aspect of the claw is produced by papillae but this horn is very friable. Canine 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 it is cut into.

{{OpenPages}}
[[Category:Musculoskeletal System - Anatomy & Physiology]]
[[Category:A&P Done]]

Forelimb - Anatomy & Physiology

2012-05-05T22:11:01Z

JamiVet: /* Humerus */

==Common structures of the Proximal Forelimb and Shoulder==

===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. In ungulates, the dorsal border is extended by a scapular cartilage, which enlarges the area for muscle attachment. This ossifies with age. The bone is roughly triangular, with a prominent '''spine''' that can be palpated through the skin.
:The spine:
::defines '''infraspinous''' and '''supraspinous''' '''fossae''', inhabited by the infraspinatus and supraspinatus muscles respectively
::serves as a point of attachment for the '''trapezius''' muscle
::culminates in the '''acromion''' in all but the horse and pig.
::the cat also possesses a suprahamate process which lies proximal to the acromion and projects caudally.

Just cranial to the glenoid cavity can be seen a bony prominence called the supraglenoid tubercle which is the origin of the biceps bracii muscle

Medial muscle attachment consist mostly of the '''subscapularis''', with the '''serratus ventralis''' attaching dorsally. The Scapula articulates with the humerus at the '''glenoid cavity'''.

===Clavicle===

The Clavicle is all but absent in most domestic species, with the notable exception of the avian skeleton. In the dog and cat, a remnant of bone may remain embedded in the fibrous intersection in the brachiocephalicus muscle, which may prove misleading in radiographic images.

===Humerus===

The Humerus is the long bone of the arm, 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 head of the humerus comprises '''greater''' and '''lesser tubercles''', separated by an '''intertubercular groove''' through which runs the tendon of the '''biceps brachii'''. The shaft of the humerus takes on a characteristically twisted shape via a groove carrying the '''brachialis''' and '''radial nerve'''. Laterally, the '''deltoid tuberosity''' is palpable through the skin and connects to the head of the humerus via a ridge and merges distally with the '''crest of the humerus'''. Distally, the humerus culminates in a '''condyle''' which articulates to form the elbow.
:In large animals, it meets the radius via a '''trochlea'''
:In dogs and cats, it articulates with the ulna medially via a trochlea and the radius laterally via a '''capitulum'''
:Caudally, all species show an '''olecranon fossa''' which articulates with the '''olecranon''' of the ulna

At the distal end of the humerus a small hole may be seen connecting the olecranon fossa caudally with the radial fossa cranially. This is the supratrochlear foramen. No structures pass through it.

Medial and lateral epicondyles provide attachment for flexors and extensors of the carpus and digits.

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

The shoulder joint links the humerus and the scapula at the '''glenoid cavity''', which is much smaller than the head of the humerus. While structurally it is a [[Joints - Anatomy & Physiology#Types of Joints|'''ball and socket''']] joint, it functions as a [[Joints - Anatomy & Physiology#Types of Joints|'''hinge joint''']] due to extensive muscling around the articulation. The joint capsule is enlarged and extends under the tendon of the biceps, acting as a synovial sheath to protect the tendon.

It is important to distinguish the shoulder/scapulohumeral joint from the entirely muscular connection (synsarcosis) between the forelimb and the trunk. This latter connection is sometimes called the '''girdle muscles''', although this is a problematic term, because many of its constituent muscles do not attach to a limb girdle muscle. At Cambridge University, it has for some time been given the name '''omothoracic junction''', but this term has not entered common usage.

There are no true ligaments in the shoulder joint. The tendons of insertion of the supraspinatous and infraspinatous muscles cross the shoulder joint and insert laterally on the greater tubercle of the humerus. The tendon of the subscapularis inserts medially on the humerus. These act as 'ligaments' preventing dislocation of the shoulder.

===Elbow Joint===

Movement of the elbow joint is restricted to the [[Planes and Axes - Anatomy & Physiology|sagittal plane]]. It is bounded medially and laterally by collateral ligaments between the humerus and radius, caudally by the olecranon ligament between the humerus and olecranon, and further enforced by the annular radial ligament. The elbow is a compound joint including:
*The [[Joints - Anatomy & Physiology#Types of Joints|'''hinge joint''']] between the humerus and the radius and ulna.
*The [[Joints - Anatomy & Physiology#Types of Joints|'''pivot joint''']] between the radius and ulna.
*The point of the elbow, or the '''olecranon''' is formed by the anconeal process of the ulna inserting into the olecranon fossa of the humerus.

==Common Structures of the Distal Forelimb==
===Radius===

While in the human the radius and ulna are separated by an interosseus space and articulate only at their extremities, allowing for significant capability of supination and pronation, these movements are much more limited in domestic animals due to the gradual fusing of the two bones. The extreme case is exhibited by the horse.

The radius forms the shaft-like rod of the distal limb, which is bowed to varying degrees amongst species. It articulates proximally with the distal humerus, caudally with the ulna, and distally with the carpus. Medially on the distal articular process, a '''styloid process''' projects, which is mirrored laterally by the ulna.

===Ulna===

The Ulna's greatest contribution to functional anatomy is in the formation of the '''olecranon''', or the point of the elbow, which gives rise to the attachment of the '''triceps''' muscle. The olecranon articulates with the humerus via its anconeal process. The olecranon develops as an apophysis, i.e.. from a separate site of ossification. The trochlear notch on the cranial aspect of the ulna articulates with the large trochlea of the humerus which forms the main elbow joint capable of flexion and extension. Just distal to the trochlear notch, a large medial '''coronoid process''' and a smaller lateral coronoid process can be seen. Distally (where unfused), the '''lateral styloid process''' articulates with the '''ulnar carpal bone'''.

===Carpal bones===

Carpal bones comprise two rows:
*Proximally, (mediolaterally), radial, intermediate, ulnar and accessory bones. The accessory bone serves as a landmark for palpation.
*Distally, bones are numbered 1-5, though 5 is always fused with 4.

A small [[Bones - Anatomy & Physiology#Types of Bone|'''sesamoid''']] bone embedded in the medial tissues of the joint can sometimes be mistaken as a chip fracture.

===Metacarpal bones===

The number of metacarpals varies widely among species, as the demand for their function changes: '''plantigrade''', or flat-footed, animals requiring the full complement of five metacarpal bones; the number is reduced in the upright stature of '''digitigrade''' animals such as the dog and cat, and shows the extreme in '''unguligrades''' like the horse, which depends entirely on the third metacarpal bone for its stature.

Colloquially, the third metacarpal of the horse is known as the '''canon''' bone, and the vestigial 2 and 4 as '''splint bones'''

==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, compring a common outer fibrous capsule and three inner synovial pouches, one for each joint. Numerous ligaments add to the stability of the joint and ensure movement is largely limited to the [[Planes and Axes - Anatomy & Physiology|sagittal plane]], although no collateral ligaments exist in the dog between the radius and the proximal metacarpals. This allows a very small amount of rotation.

===Metacarpal Joint===

The metacarpal joint is defined by the presence of palmar [[Bones - Anatomy & Physiology#Types of Bone|'''sesamoids''']], which allow the flexor tendons to pass over the sharp change in angle presented by the joint. They are paired on each digit, with the exception of the first digit where only one exists. A single '''dorsal sesamoid bone''' can also be seen in dogs in digit 2 - 5 inclusive over the same joint between the metacarpal bone and the proximal phalanx. This is not found in ungulates or in the the first digit. However another sesamoid bone exists in the tendon of the abductor pollis longis muscle of the first digit.

==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''''':
:Innervated by: 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.''''':
:Innervated by: Accessory n.
:Two parts separated by the clavicle where it exists
:Origin: clavicle or vestigial fibrous intersection
:Insertion: several places on the head and neck
:Actions:
::advances the limb and extends the shoulder joint when limb is in motion
::draws head and neck ventrally when limb is fixed

'''''Omotransversarius''''':
:Innervated by: Accessory n.
:Origin: transverse processes of the atlas
:Insertion: acromion and adjacent scapula
:Action: advancing the limb

'''''Latissimus dorsi''''':
:Innervated by: 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.''''':
:Innervated by: 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''''':
:Innervated by: 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''''':
:Innervated by: brachial plexus, although in some species, dorsal spinal nerves can innervate
:Origin: median connective tissue from poll to withers, lying deep to the trapezius
: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''',
:Innervated by: 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:
'''Subscapularis''':
:Innervated by: 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''':
:Innervated by: Musculocutaneous n. of the brachial plexus
:Origin: medial supraglenoid tubercle
:Insertion: proximal shaft of the humerus
:Action: fixator

Caudal (Flexors):
:Innervated by: Axillary n. of the brachial plexus
:'''Deltoids'''
::Origin: caudal border and spine of the scapula, one head in the horse and two in species with an acromion (site of second 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'':
:Innervated by: Radial n. from the brachial plexus

:'''Triceps brachii''': Three heads, four 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'''
::Overlies triceps extending from scapula to olecranon

:'''Anconeus'''
::Origin: distal humerus
::Insertion: lateral olecranon

''Flexors'':
:Innervated by: 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 Supination and Pronation ====
''Supinators'':
:Innervated by: Radial n. from the brachial plexus

:'''Brachioradialis'''
::Origin: lateral epicondyle of the humerus
::Insertion: distal medial forearm within superficial fascia
::Prominent in the cat but nearly absent in the dog

:'''Supinator'''
::Deep to extensor muscles, passing from lateral humeral epicondyles to upper medial radius

''Pronators'':
:Innervated by: Median n. from the brachial plexus

:'''Pronator teres''': only functional in cat and dog
::Origin: medial epicondyle of the humerus
::Insertion: supinator

:'''Pronator quadratus''': only found in carnivores
::Origin: shaft of the ulna
::Insertion: shaft of the radius

====Muscles of the Carpal and Digital Joints====
''Extensors'':
:Innervated by: 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 paw

:'''Common Digital Extensor'''
::Insertion: extensor process of the distal phalanx of each digit
::Sends a medial branch to dew claw and medial digits in all but horse and cat

:'''Lateral Digital Extensor'''
::Insertion: dorsal proximal phalanx

''Flexors'':
:Innervated by: 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'''
::Branches according to the number of digis and inserts in proximal interphalangeal joint

:'''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]]'''

==Innervation of the Forelimb==

The nerves affecting the forelimb arise from spinal nerves C6 to T2 and pass through the '''brachial plexus'''.

'''Suprascapular Nerve'''
* Origin - cranial part of brachial plexus, C6 and C7
* Motor innervation - supraspinatus and infraspinatus
* Sensory innervation - none
* Route - out of the brachial plexus, laterally round the cranial aspect of the neck of the scapula

'''Subscapular Nerve'''
* Origin - cranial part of the brachial plexus, C6 and C7
* Motor innervation - subscapular muscle
* Sensory innervation - none
* Route - direct to muscle

'''Musculocutaneous Nerve'''
* Origin - middle part of the brachial plexus, C7 and C8 (sometimes C6)
* Motor innervation - Biceps brachii, brachialis, coracobrachialis
* Sensory innervation - dorsomedial aspect of forelimb
* Route - medial aspect of the limb, close to the median nerve

'''Axillary Nerve'''
* Origin - middle brachial plexus, C7 and C8
* Motor innervation - shoulder flexors, teres minor, deltoid
* Sensory innervation - dorso-lateral aspect of proximal limb
* Route - behind the shoulder joint

'''Radial Nerve'''
* Origin - caudal brachial plexus, C7 to T2
* Motor innervation - extensors of elbow, carpus and digits
* Sensory innervation - dog: craniolateral and medial forearm, horse: lateral forearm
* Route - through the triceps, around the humerus to the lateral aspect of the forearm

'''Median and Ulnar Nerves'''
* Origin - caudal brachial plexus, C8, T1 and T2
* Motor innervation - flexors of carpus and digits
* Sensory innervation - caudal aspect of the limb
* Route - along the medial aspect of the limb, the median forms branches to the musculocutaneous nerve

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

[[Category:Musculoskeletal System - Anatomy & Physiology]]
[[Category:A&P Done]]

West Indies - University of the West Indies, School of Veterinary Medicine, Trinidad and Tobago

2012-04-23T11:27:30Z

JamiVet:

{{Vetschool
|Introduction=[http://sta.uwi.edu/fms/vet/ The School of Veterinary Medicine, UWI] of the St. Augustine Campus is located at the Eric Williams Medical Sciences Complex, Mount Hope. Together with the schools of Medicine, Dentistry and Pharmacy, the "one medicine" concept is promoted, reflecting the connection between human and animal medicine. We are the only veterinary school in the Caribbean that offers a complete veterinary programme, both clinical and non clinical at a single site. A system- based approach to learning especially during clinical years and Problem-Based learning in non-clinical and clinical years is utilized. We are an experienced multinational faculty, producing world class veterinarians and researchers. The School of Veterinary Medicine, UWI follows the Global Veterinary Curriculum but has a special interest in tropical veterinary medicine, with clinical exposure to exotic diseases.
|History=
|Education=The SVM at the University of the West Indies offers undergraduate, postgraduate as well as a professional development programme. 

There are three entry levels to the undergraduate programme where upon successful completion, candidates are awarded with the Doctor of Veterinary Medicine (DVM) degree. 
There is the six years programme: it comprises of a one year pre-veterinary curriculum which lasts for three semesters, followed by five years of veterinary course work. There is five year programme which the most popular entry level and the four year programme where students with a first degree in the field of biology, chemistry or related fields are accepted.
 For more info: [http://sta.uwi.edu/fms/vet/dvm.asp Doctor of Veterinary Medicine]

The research and postgraduate programme offered at the SVM include M.Phil. & Ph.D. degrees where candidates where it is possible to do:
<ul>
<li>basic science research</li>
<li> applied science research</li>
<li> clinical research</li>
</ul>
For more info: [http://sta.uwi.edu/fms/vet/research.asp Research]

Also offered are professional development courses, such as emergency medicine.

|Research=Along with postgraduate ongoing research, undergraduates also participate in research in the form of simple projects, which begins at level three and lasts for five (5) semesters.
It provides the students with the basic skills and knowledge required in the complete execution of a scientific investigation under the supervision of a member of the academic staff. There are several areas of ongoing research such as
<ul><li>Anatomy.</li>
<li>Physiology.</li>
<li>Public Health.</li>
<li>Pathology.</li>
<li>Parasitology.</li>
<li>Clinical Medicine.</li>
<li>etc</li>
</ul>

|Clinical=There are current several services provided at the UWI, School of Veterinary Medicine. They include:
<ul>
<li>Aquaculture & Aquatic Animal Health.</li>
<li>Plastination</li>
<li>Diagnostic Laboratory Services</li>
<li>Hospital Services</li>
<li>Food Safety</li>
<li>Equine</li>
<li>and other Services</li>
</ul>

|MainImage=
|Image3=
|Image2=
|School=School of Veterinary Medicine, UWI
|Established=
|Location=St. Augustine, Trinidad and Tobago
|Principal= Director of SVM 
Professor A.A. Adesiyun
|Students=
|Undergraduates=
|Postgraduates=
|Website=http://sta.uwi.edu/fms/vet/index.asp
|Contact=School of Veterinary Medicine, 
Faculty of Medical Sciences, 
Eric Williams Medical Sciences Complex, 
Uriah Butler Highway, 
Champ Fleurs, 
Trinidad, West Indies 

'''Tel:''' (868) 645 4481
|Facebook page=
|Student Ambassador=[[User:JamiVet|Jamila Beard]]
}}

Cell Growth Disorders

2012-04-22T21:01:58Z

JamiVet: /* Aplasia */

==Aplasia==
Aplasia also known as agenesis is the complete failure of an organ or part to form during embryogenesis.

Examples
<ul>
<li>inherited genetic defects</li>
<li>absence of limbs or amelia</li>
</ul>

==Atrophy==
Atrophy is a decrease in the size of the cells and organ, occurring after the organ has reached normal size.

===Appearance===
* Atrophic tissues and organs appear smaller and perhaps paler than usual.
* Microscopy of atrophic tissue shows:
** Cells of a smaller size.
** Inactive appearance.
** A relative increase in the supportive connective tissue.

===Causes===

* Starvation
* Malabsorption
* Compression
** E.g by a nearby lesion.
* Immobilisation
** Immobilisation of a limb results in atrophy of the muscles.
* Denervation
* Lack of trophic hormones
* Chronic inflammation
** May be idiopathic.

===Examples===

====Serous Atrophy of Adipose Tissue====

* Also known as gelatinous atrophy of adipose tissue.
* The fat becomes transparent, watery and severely depleted.
* Occurs as a result of severe debilitation and weight loss.

====Brown Atrophy====

* A senile change in muscles where they appear brownish rather than reddish in colour.
* Due to the intracytoplasmic accumulation of [[Pigmentation - Pathology#Lipofuscin|lipofuscin]] within the muscle fibres.
** The "wear and tear" pigment.

==Hypertrophy==

* Hypertrophy is an increase in the size of an organ due to an increase in size of the individual cells.
** The organ also gains in weight.

===Types===

====Functional Hypertrophy====

* Occurs in response to:
** An increased physiological need.
*** E. g. muscles of the heart and limbs in training.
** An increased demand because of organ dysfunction.
*** E.g in cardiac hypertrophy due to a progressively failing heart.

====Compensatory Hypertrophy====

* Occurs when one of a paired organ is damaged or lost.
** E.g. the kidney.

====Obstructional Hypertrophy====

* Hollow organs may become thickened around an obstruction.
** E. g. intestine, bladder, [[Gall Bladder - Anatomy & Physiology|gall bladder]].

====Hormonal Mediated Hypertrophy====

* Anabolic steroids produce hypertrophy of muscle.
* Thyroid hormones have a general hypertrophic effect on tissues.
** Increase protein synthesis within them.
** The heart can become quite hypertrophied in thyroid excess.
*** Commonly seen in older cats which often develop hyperthyroidism.

==Hypoplasia==

* Hypoplasia is a reduction in the size of cells and tissues,.
* Due to a failure to grow to normal size.
* Ranges from mild hypoplasia to almost complete absence.
** Almost complete absence is also called vestigial or rudimentary.
* Aplasia and agensis refer to complete absence of tissue.
** Generally refer to the gross appearance rather than the microscopic appearance.
*** Some rudimentary tissue can be seen if searched for carefully.

==Hyperplasia==

* Hyperplasia is an increase in the size of an organ due to an increase in the numbers of cells present within it.
* Hypertrophy and hyperplasia may occur concurrently.
* The hyperplastic response stops when the inciting agent ceases.
* Hyperplastic tissue is more prone to injury by chemicals, and also may be more prone to undergo neoplastic change in some cases.

===Causes===
[[Image:benign prostatic hyperplasia.jpg|thumb|right|150px|Benign prostatic hyperplasia (Courtesy of BioMed Archive)]]
* Hormonal stimulation.
** Parathyroid hyperplasia in chronic renal failure.
** Prostatic hyperplasia in older dogs.
* Hyperplasia may also occur as a regenerative response to
** Irritation
** Cell loss
** Injury

===Gross Appearance===

* Hyperplastic nodules can be seen in a variety of organs in older dogs and cats.
** Particularly the thyroid in cats, and the spleen and [[Liver - Anatomy & Physiology|liver]] of dogs.

===Histological Appearance===

* Hyperplasia is characterised by an increase in the numbers of cells.
* Mitotic activity is not always seen.
* There is some increase in cellular basophilia.
* The cells are well differentiated and tissue structure is normal.

==Metaplasia==

* Metaplasia is a transformation of one type of tissue into another.
* Occurs solely in:
** '''Connective tissue'''
*** The metaplastic change id to cartilage and bone in damaged tissue.
*** Caesarean scars in the pig are especially prone to osseous metaplasia.
** '''Epithelium'''
*** Squamous metaplasia of cuboidal or columnar epithelium is quite common.
**** Seen in the prostate of dogs under the influence of oestrogens.
***** Oestrogens are present in Sertoli cell tumours and in Vit. A deficiency.
**** The most striking example is the squamous metaplasia of the oesophageal glands in the chicken.
* Mixed tumours of the mammary gland of the dog are so called because there is proliferation of both the glandular element and the surrounding myoepithelium.
** The myoepithelium can transform into cartilage and bone.
*** Some regard this as a metaplastic change.
*** The bone formed may even show marrow formation within the spaces between the bony trabeculae.

==Dysplasia==

* Dysplasia is abnormal growth within a tissue.
* The normal arrangement and pattern of the tissue may be lost.
* The most common example is the renal dysplasia in some breeds of dogs.
** Causes fibrous tracts.
** Because of the reduction in functional tissue, gives a predisposition to renal failure early in life in the more severely affected cases.

==Anaplasia==

* Anaplasia is a marked and irreversible loss of cellular differentiation with return to a more primitive state.
* Afeature of highly malignant tumours.
* There is no pattern, just a diffuse sheet of cells.
* Both cells and nuclei are of differing sizes.
* There are prominent nucleoli in some nuclei.

==Neoplasia==
[[Neoplasia - Pathology|Neoplasia]]

[[Category:General Pathology]]

Cell Growth Disorders

2012-04-22T20:57:18Z

JamiVet:

==Aplasia==
Aplasia also known as agenesis is the complete failure of an organ or part to form during embryogenesis.

==Atrophy==
Atrophy is a decrease in the size of the cells and organ, occurring after the organ has reached normal size.

===Appearance===
* Atrophic tissues and organs appear smaller and perhaps paler than usual.
* Microscopy of atrophic tissue shows:
** Cells of a smaller size.
** Inactive appearance.
** A relative increase in the supportive connective tissue.

===Causes===

* Starvation
* Malabsorption
* Compression
** E.g by a nearby lesion.
* Immobilisation
** Immobilisation of a limb results in atrophy of the muscles.
* Denervation
* Lack of trophic hormones
* Chronic inflammation
** May be idiopathic.

===Examples===

====Serous Atrophy of Adipose Tissue====

* Also known as gelatinous atrophy of adipose tissue.
* The fat becomes transparent, watery and severely depleted.
* Occurs as a result of severe debilitation and weight loss.

====Brown Atrophy====

* A senile change in muscles where they appear brownish rather than reddish in colour.
* Due to the intracytoplasmic accumulation of [[Pigmentation - Pathology#Lipofuscin|lipofuscin]] within the muscle fibres.
** The "wear and tear" pigment.

==Hypertrophy==

* Hypertrophy is an increase in the size of an organ due to an increase in size of the individual cells.
** The organ also gains in weight.

===Types===

====Functional Hypertrophy====

* Occurs in response to:
** An increased physiological need.
*** E. g. muscles of the heart and limbs in training.
** An increased demand because of organ dysfunction.
*** E.g in cardiac hypertrophy due to a progressively failing heart.

====Compensatory Hypertrophy====

* Occurs when one of a paired organ is damaged or lost.
** E.g. the kidney.

====Obstructional Hypertrophy====

* Hollow organs may become thickened around an obstruction.
** E. g. intestine, bladder, [[Gall Bladder - Anatomy & Physiology|gall bladder]].

====Hormonal Mediated Hypertrophy====

* Anabolic steroids produce hypertrophy of muscle.
* Thyroid hormones have a general hypertrophic effect on tissues.
** Increase protein synthesis within them.
** The heart can become quite hypertrophied in thyroid excess.
*** Commonly seen in older cats which often develop hyperthyroidism.

==Hypoplasia==

* Hypoplasia is a reduction in the size of cells and tissues,.
* Due to a failure to grow to normal size.
* Ranges from mild hypoplasia to almost complete absence.
** Almost complete absence is also called vestigial or rudimentary.
* Aplasia and agensis refer to complete absence of tissue.
** Generally refer to the gross appearance rather than the microscopic appearance.
*** Some rudimentary tissue can be seen if searched for carefully.

==Hyperplasia==

* Hyperplasia is an increase in the size of an organ due to an increase in the numbers of cells present within it.
* Hypertrophy and hyperplasia may occur concurrently.
* The hyperplastic response stops when the inciting agent ceases.
* Hyperplastic tissue is more prone to injury by chemicals, and also may be more prone to undergo neoplastic change in some cases.

===Causes===
[[Image:benign prostatic hyperplasia.jpg|thumb|right|150px|Benign prostatic hyperplasia (Courtesy of BioMed Archive)]]
* Hormonal stimulation.
** Parathyroid hyperplasia in chronic renal failure.
** Prostatic hyperplasia in older dogs.
* Hyperplasia may also occur as a regenerative response to
** Irritation
** Cell loss
** Injury

===Gross Appearance===

* Hyperplastic nodules can be seen in a variety of organs in older dogs and cats.
** Particularly the thyroid in cats, and the spleen and [[Liver - Anatomy & Physiology|liver]] of dogs.

===Histological Appearance===

* Hyperplasia is characterised by an increase in the numbers of cells.
* Mitotic activity is not always seen.
* There is some increase in cellular basophilia.
* The cells are well differentiated and tissue structure is normal.

==Metaplasia==

* Metaplasia is a transformation of one type of tissue into another.
* Occurs solely in:
** '''Connective tissue'''
*** The metaplastic change id to cartilage and bone in damaged tissue.
*** Caesarean scars in the pig are especially prone to osseous metaplasia.
** '''Epithelium'''
*** Squamous metaplasia of cuboidal or columnar epithelium is quite common.
**** Seen in the prostate of dogs under the influence of oestrogens.
***** Oestrogens are present in Sertoli cell tumours and in Vit. A deficiency.
**** The most striking example is the squamous metaplasia of the oesophageal glands in the chicken.
* Mixed tumours of the mammary gland of the dog are so called because there is proliferation of both the glandular element and the surrounding myoepithelium.
** The myoepithelium can transform into cartilage and bone.
*** Some regard this as a metaplastic change.
*** The bone formed may even show marrow formation within the spaces between the bony trabeculae.

==Dysplasia==

* Dysplasia is abnormal growth within a tissue.
* The normal arrangement and pattern of the tissue may be lost.
* The most common example is the renal dysplasia in some breeds of dogs.
** Causes fibrous tracts.
** Because of the reduction in functional tissue, gives a predisposition to renal failure early in life in the more severely affected cases.

==Anaplasia==

* Anaplasia is a marked and irreversible loss of cellular differentiation with return to a more primitive state.
* Afeature of highly malignant tumours.
* There is no pattern, just a diffuse sheet of cells.
* Both cells and nuclei are of differing sizes.
* There are prominent nucleoli in some nuclei.

==Neoplasia==
[[Neoplasia - Pathology|Neoplasia]]

[[Category:General Pathology]]

User:JamiVet

2012-04-18T21:45:29Z

JamiVet:

{{UserPage
|Name=Jamila Beard
|Occupation= Veterinary Student 
|School= West Indies - University of the West Indies School of Veterinary Medicine
|Year= 2015
|Email= jamila.beard@my.uwi.edu
|Image=PigeonPointTobago.jpg
}}

User:JamiVet

2012-04-18T15:40:59Z

JamiVet: