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| | ==Thoracic Limb== | | ==Thoracic Limb== |
| − | ===Extrinsic Musculature===
| + | <big><b> |
| − | | + | :[[Thoracic Limb Extrinsic Muscles - Horse Anatomy|Extrinsic Musculature]] |
| − | These muscles 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 to stabilize the scapula.
| + | :Intrinsic Musculature |
| − | | + | ::[[Shoulder Muscles - Horse Anatomy|Muscles of the Shoulder]] |
| − | ====Superficial Musculature====
| + | ::[[Elbow Muscles - Horse Anatomy|Muscles of the Elbow]] |
| − | '''''Trapezius'''''
| + | ::[[Carpal and Digital Muscles - Horse Anatomy| Muscles of the Carpal and Digital Joints]] |
| − | :'''Innervatation''': Accessory n. | + | </b></big> |
| − | :'''Origin''': Mid-dorsal raphe and supraspinous ligament
| |
| − | :'''Insertion''': Spine of the scapula | |
| − | :'''Body''': Two parts, cervical and thoracic, separated by aponeurosis
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| − | :'''Action''': Raises the scapula against the trunk and swings cranially to advance the limb
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| − | | |
| − | '''''Brachiocephalic'''''
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| − | :'''Innervation''': Accessory n.
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| − | :Two parts ('''cleidobrachial''' and '''cleidocephalic''' muscle) separated by the clavicle, where it exists
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| − | :'''Origin''': Mastoid process of temporal bone, nuchal crest, wing of atlas and the transverse processes of the 2nd-4th cervical vertebrae
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| − | :'''Insertion''': Deltoid tuberosity and crest of the humerus
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| − | :'''Action''': Advances the limb and extends the shoulder joint when limb is in motion. Draws the head and neck ventrally when the limb is fixed
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| − | | |
| − | '''''Cleidomastoid'''''
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| − | :'''Innervatation''': Accessory n. and Axillary n.
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| − | :'''Origin''': Mastoid process of the temporal bone and nuchal crest
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| − | :'''Insertion''': Deltoid tuberosity, crest of the humerus and fascia of the shoulder as the '''cleidobrachialis''' muscle
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| − | :'''Action''': If acting bilaterally, it draws the head and neck down and backwards. If the acting with one shoulder fixed, it draws the head, upper arm fascia and neck to one side.
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| − | | |
| − | '''''Latissimus dorsi'''''
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| − | :'''Innervation''':Local branch of brachial plexus
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| − | :The broadest muscle of the back
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| − | :'''Origin''': Thoracolumbar fascia
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| − | :'''Insertion''': Teres tuberosity of the humerus
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| − | :'''Action''': Antagonist to the brachiocephalic m. It retracts the free limb and flexes shoulder joint. It also draws the trunk forward over the fixed limb.
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| − | | |
| − | '''''Superficial Pectorals'''''
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| − | :'''Innervation''': Brachial plexus
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| − | :Two muscles, cranial ('''descending''') and caudal ('''transverse''')
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| − | :'''Origin''':
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| − | ::Cranial ('''descending''') - Manubrium of the sternum
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| − | ::Caudal ('''transverse''') - First six costal cartilages and ventral sternum
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| − | :'''Insertion''':
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| − | ::Cranial ('''descending''') - The crest of the humerus, distal to the deltoid tuberosity
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| − | ::Caudal ('''transverse''') - Covers the elbow joint to insert on the medial fascia of the forearm
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| − | :'''Action''': Adducts the forelimb, assist in protraction and retraction
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| − | The cranial ('''descending''') pectoral muscle forms a visible prominence cranial to the sternum; extending between the manubrium and the humeral crest.
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| − | | |
| − | ====Deep Musculature====
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| − | | |
| − | '''''Deep Pectorals'''''
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| − | :'''Innervation''': Cranial and caudal thoracic n. | |
| − | :'''Origin''': Xiphoid and 4th costal cartilages of the sternum
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| − | :'''Insertion''': Two branches on the lesser and greater tubercles of the humerus, supraglenoid tubercle of scapula
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| − | :'''Action''':Draws the limb back, supports the trunk, moves the trunk cranially over an advanced limb and extends the shoulder.
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| − | | |
| − | | |
| − | '''''Serratis ventralis'''''
| |
| − | :Divided into cranial ('''cervical''') and caudal ('''thoracic''') parts.
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| − | :'''Innervation''': Dorsal and ventral Cervical n., long thoracic n.
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| − | :'''Origin''': 1st-7th rib, transverse process of cervical vertebrae
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| − | :'''Insertion''': Medial scapula and scapular cartilage
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| − | :'''Action''': Supports the weight of the trunk. It is reinforced by strong fascia. The cervical portion can retract the limb and the caudal portion can advance the limb.
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| − | | |
| − | '''''Rhomboids'''''
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| − | :Deep to the trapezius, forms the withers region. Divided into cervical and thoracic parts.
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| − | :'''Innervation''': Dorsal and ventral branches of Cervical n., Long thoracic n.
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| − | :'''Origin''':
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| − | ::Cervical - Nuchal ligament at the axis
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| − | ::Thoracic - Spinous processes of 2nd-6th cervical and 7th thoracic vertebrae
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| − | :'''Insertion''':
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| − | ::Cervical - Unites with trapezius to insert on scapular cartilage
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| − | ::Thoracic - Scapula
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| − | :'''Action''': Draws the limb forward and elevates the limb and neck. Fixes the scapula against the trunk.
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| − | | |
| − | ===Intrinsic Musculature===
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| − | | |
| − | ====Muscles of the Shoulder====
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| − | | |
| − | These muscles are grouped:
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| − | | |
| − | ====='''Lateral'''=====
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| − | | |
| − | '''''Supraspinatus '''''
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| − | :'''Innervation''':Suprascapular n. of the brachial plexus | |
| − | :'''Origin''': Supraspinous fossa of the scapula
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| − | :'''Insertion''': Lesser and greater tubercles of the humerus
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| − | :'''Action''': Extends and braces the shoulder
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| − | | |
| − | '''''Infraspinatus'''''
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| − | :'''Innervation''':Suprascapular n. of the brachial plexus
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| − | :'''Origin''': Supraspinatous fossa and spine of the scapula
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| − | :'''Insertion''': Tendon of insertion bifurcates into a deep part and a superficial part.
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| − | :: Deep - Greater tubercle of the humerus
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| − | :: Superficial - Lateral humerus, distal to the greater tubercle
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| − | :'''Action''': Brace the shoulder, supporting flexion or extension.
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| − | :'''Clinical significance''': The bursa between the superficial tendon of the infraspinatus, and the lateral tubercle of the humerus can be the site of inflammation (bursitis).
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| − | | |
| − | ====='''Medial'''=====
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| − | | |
| − | '''''Supscapularis'''''
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| − | :'''Innervation''': Subscapular n. from the brachial plexus
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| − | :'''Origin''': Deep surface of the scapula
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| − | :'''Insertion''': Lesser tubercle of the humerus
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| − | :'''Action''': Braces medial shoulder joint. Primarily acts as an extensor of the shoulder, but can contribute to maintaining flecion.
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| − | | |
| − | '''''Coracobrachialis'''''
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| − | :'''Innervation''': Musculocutaneous n. of the brachial plexus
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| − | :'''Origin''': Coracoid process of scapula
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| − | :'''Insertion''': Proximal shaft of the humerus
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| − | :'''Action''': Fixator
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| − | | |
| − | ====='''Caudal (Flexors)'''=====
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| − | | |
| − | '''''Deltoid'''''
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| − | :'''Innervation''': Axillary n. of the brachial plexus
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| − | :'''Origin''': Caudal border and spine of the scapula. One head in the horse, compared with two in species with an acromion (site of second origin.
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| − | :'''Insertion''': Deltoid tuberosity of humerus
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| − | :'''Action''': Flexes shoulder
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| − | :In the horse, the aponeurosis if the deltoid is partially fused to the infraspinatus.
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| − | | |
| − | '''''Teres Major'''''
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| − | :'''Innervation''': Axillary n. of the brachial plexus
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| − | :'''Origin''': Dorsal part of the caudal scapula
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| − | :'''Insertion''': Teres major tuberosity midway down the humerus
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| − | :'''Action''': Flexes the shoulder, supports adduction.
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| − | | |
| − | '''''Teres Minor'''''
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| − | :'''Innervation''': Axillary n. of the brachial plexus
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| − | :'''Origin''': Distal third of scapula, deep to the deltoid
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| − | :'''Insertion''': Teres minor tuberosity midway down the humerus
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| − | :'''Action''': Flexes the shoulder
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| − | | |
| − | NB// There are no defined extensors of the shoulder. Those involved (brachiocephalic m., biceps brachii, supraspinatus, and ascending pectorals) have other, more primary roles.
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| − | | |
| − | ====Muscles of the Elbow====
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| − | | |
| − | ====='''Extensors'''=====
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| − | | |
| − | '''''Triceps brachii'''''
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| − | :'''Innervation''': Radial n. from the brachial plexus | |
| − | :It has three heads:
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| − | :'''Origin''':
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| − | ::''Long'' head: Caudal margin of the scapula
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| − | ::''Lateral'' and ''Medial'' heads: Shaft of the humerus (lateral and medial aspects, respectively)
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| − | :'''Insertion''': Olecranon, proteced by the tricipital bursa against the bone, and subcutaneous bursa against the skin
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| − | :'''Action''': Extends and stabilizes the elbow
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| − | | |
| − | '''''Tensor fasciae antebrachii'''''
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| − | :'''Innervation''': Radial n. from the brachial plexus
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| − | :Overlies the triceps extending from the scapula to the olecranon
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| − | :'''Origin''': Caudal border of the scapula
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| − | :'''Insertion''':Antebrachial fascia
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| − | :'''Action''': Tenses antibrachial fascia and extends the elbow
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| − | | |
| − | '''''Anconeus'''''
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| − | :'''Innervation''': Radial n. from the brachial plexus
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| − | :'''Origin''': Distal humerus and olecranon fossa,deep to the triceps
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| − | :'''Insertion''': Lateral olecranon, joining the lateral head of the triceps
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| − | :'''Action''': Extends the elbow
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| − | | |
| − | ====='''Flexors'''=====
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| − | | |
| − | '''''Biceps brachii'''''
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| − | :'''Innervation''': Musculocutaneous n. from the brachial plexus
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| − | :'''Origin''': Supraglenoid tubercle of the scapula
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| − | :'''Insertion''': Distally, the muscle divides into a medial and lateral portion.
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| − | :: Medial - Medial tuberosity on the proximal radius
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| − | :: Lateral - Proximal radius and ulna
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| − | :It runs through the intertubercular groove of the humerus facilitated by the '''bicipital bursa'''.
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| − | ::'''Action''': Flexes the elbow, extends and stabilises the shoulder during the stance phase
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| − | | |
| − | '''''Brachialis'''''
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| − | :'''Innervation''': Musculocutaneous n. from the brachial plexus
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| − | :'''Origin''': Proximocaudal humerus
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| − | :'''Insertion''': Spirals to insert next to biceps on the medial radius
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| − | :'''Action''': Flexes the elbow
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| − | | |
| − | ====Muscles of the Carpal and Digital Joints====
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| − | The horse, as well as other domestic mammals, have a limited range of motion in the carpal joints compared with humans; therefore these muscles act as either extensors or flexors.
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| − | | |
| − | ====='''Extensors'''=====
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| − | | |
| − | The craniolateral position on the forearm, almost all originate from the lateral epicondyle of the humerus. All innervated by the radial n. from the brachial plexus.
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| − | | |
| − | '''''Extensor carpi radialis'''''
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| − | :The most medial
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| − | ::'''Insertion''': Metacarpal tuberosity of the proximal third metacarpal (cannon) bone. Uniquely in the horse, the lacertus fibrosus (detachment of the ''biceps brachii'') joins this muscle prior to its insertion.
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| − | ::'''Action''': Extends and fixes the carpus, flexes the elbow
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| − | | |
| − | '''''Extensor carpi obliquus''''' (aka '''''abductor pollicis longus''''')
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| − | :'''Origin''': Cranial radius
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| − | :'''Insertion''': Head of second metacarpal (medial splint) bone
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| − |
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| − | '''''Common Digital Extensor'''''
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| − | : Deep to the ''extensor carpi radialis''
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| − | :'''Insertion''': Extensor process of the distal phalanx via the common digital extensor tendon
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| − | :'''Action''': Extends carpus and digit
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| − | | |
| − | '''''Lateral Digital Extensor'''''
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| − | : Caudal to the ''common digital extensor'' muscle on the lateral antebrachium
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| − | :'''Insertion''': Dorsoproximal phalanx via the lateral digital extensor tendon
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| − | :'''Action''': Extends the carpus and metacarpophalangeal (fetlock) joint
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| − | | |
| − | ====='''Flexors'''=====
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| − | | |
| − | Caudal position on the forearm, originate from the caudal medial epicondyle of the humerus. All innervated by the median or ulnar n. of the brachial plexus.
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| − | | |
| − | '''''Flexor carpi radialis'''''
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| − | :The most medial, inserts on the proximal part of the second metacarpal(medial splint)bone
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| − | | |
| − | '''''Flexor carpi ulnaris'''''
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| − | :The most lateral, inserts on the accessory carpal bone.
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| − | | |
| − | '''''Ulnaris lateralis'''''
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| − | :The most caudolateral
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| − | :'''Insertion''': Accessory carpal bone and the fourth metacarpal (lateral splint) bone.
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| − | :'''Action''': Flexes the carpus rather than extends it, due to its insertion caudal to the carpal joint axis.
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| − | | |
| − | '''''Superficial Digital Flexor'''''
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| − | : Overlies, and is partially fused with, the ''deep digital flexor'' muscle.
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| − | :'''Insertion''': Proximal extremity of middle phalanx and the distal extremity of proximal phalanx via the superficial digital flexor tendon.
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| − | | |
| − | '''''Deep Digital Flexor'''''
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| − | :Deep to the ''superficial digital flexor'' muscle and flexor muscles of the carpus. Passes through the carpal canal before branching and continues to insert on the palmar distal phalanx via the deep digital flexor tendon.
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| − | | |
| − | '''''Interosseus muscle/Suspensory ligament'''''
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| − | :This is covered in more detail in the [[Tendons - Horse Anatomy|Equine Tendons]] section.
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| | | | |
| | ==Pelvic Limb== | | ==Pelvic Limb== |
| − | The muscles affecting the pelvic girdle and hip can be divided into two distinct groups; girdle muscles and rump muscles.
| + | <big><b> |
| − | <br /> | + | :[[Pelvic Girdle Muscles - Horse Anatomy|Girdle Muscles]] |
| − | <br /> | + | :[[Rump Muscles - Horse Anatomy|Rump Muscles]] |
| − | ====[[Hindlimb - Anatomy & Physiology#Girdle Muscles|Girdle Muscles]]====
| + | :[[Inner Pelvic Muscles - Horse Anatomy|Inner Pelvic Muscles]] |
| − | The pelvic girdle muscles is made up of a number of distinct muscle groups.
| + | :[[Muscles of the Crus - Horse Anatomy|Muscles of the Crus]] |
| − | | + | </b></big> |
| − | '''''Psoas Minor'''''
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| − | | |
| − | The psoas minor muscle is marked by many tendinous intersections.
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| − | | |
| − | '''''Iliac'''''
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| − | | |
| − | The iliac muscle is 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.
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| − | | |
| − | '''''Quadrate Lumbar'''''
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| | | | |
| − | The quadrate lumbaris 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.
| + | ==References== |
| − | <br />
| + | *Konig, H.E., Liebich, H.G. Veterinary Anatomy of Domestic Mammals: Textbook and Colour Atlas (2009), Schattauer |
| − | <br />
| + | *Pasquini, C, Spurgeon, T.L., An Anatomy of Domestic Animals: A Systemic and Regional Approach, 10th Edition (2003), Bowker |
| − | | |
| − | ====[[Hindlimb - Anatomy & Physiology#Rump Muscles|Rump Muscles]]==== | |
| − | The rump muscles are also made up of a number of different muscle groups and have considerably more groups than the girdle muscles.
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| − | | |
| − | '''''Superficial Gluteal'''''
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| − | | |
| − | The superficial gluteal originates in the gluteal fascia and unites with the tensor muscle fascia lata, passing over the greater trochanter and attaching onto the third trochanter which radiates into the femoral fascia. A synovial bursa exists between the tendinous insertion and the third trochanter.
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| − | | |
| − | '''''Middle Gluteal'''''
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| − | | |
| − | The middle gluteal originates from four separate areas; the 1st lumbar vertebrae, aponeurosis of the longissimus muscle, the sacrum and the broad sacrotuberous ligament. The short portion of this muscle inserts on the greater trochanter whilst the deep portion inserts on both the greater trochanter and intertrochanteric crest.
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| − | | |
| − | '''''Tensor Muscle of the Fascia Lata'''''
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| − | | |
| − | The tensor muscle of the fascia lata originates from the coxal tuberosity and 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.
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| − | | |
| − | '''''Biceps Femoris'''''
| |
| − | | |
| − | The biceps originate from the vertebral head which is a spinous processes of the sacral vertebrae, and also from the caudal border of the sacrotuberous ligament and the ischial tuberosity. The two bellies of the '''biceps''' then unite and redivide into three parts that form an extensive aponeurosis. The cranial branch of the aponeurosis inserts just distal to the third trochanter on the caudal aspect of the femur, to the patella and to the lateral patellar ligament. The middle branch inserts onto the crural fascia, the lateral patellar ligament and the cranial aspect of the tibia. The caudal branch radiates into the crural fascia and forms the tarsal tendon. This combines with the detachment from the semitendinous inserts on the calcaneus.
| |
| − | | |
| − | '''''Semitendinosus'''''
| |
| − | | |
| − | The semitendinous muscle originates from various points including; the pelvic head, the ventral aspect of ischial tuberosity, the sacrum, 1st caudal vertebrae and the sacrotuberous ligament. The two bellies of the '''semitendinous''' then unite and run as a flat tendon to the medial side of the leg. It then partially fans out into the crural fascia and partially inserts onto the cranial aspect of the tibia. The remaining tendon joins the tarsal tendon.
| |
| − | | |
| − | '''''Semimembranosus'''''
| |
| − | | |
| − | The semimembranous also originates from various points including the vertebral head (sacrotuberous ligament), 1st caudal vertebrae, pelvic head and the ventral aspect of ischial tuberosity. The two bellies of the muscle then unite and insert at three places; the medial femoral condyle via a short tendon, the medial collateral ligament of the femerotibial joint and to the medial condyle of the tibia via an aponeurosis.
| |
| − | | |
| − | '''''Sartorius'''''
| |
| − | | |
| − | The sartorius muscle originates from the iliac fascia and the tendon of the '''psoas minor'''. It inserts via the medial patellar ligament, crural fascia and the tibial tuberosity.
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| − | | |
| − | '''''Gracilis'''''
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| − | | |
| − | The gracilis originates from the accessory ligament of the femoral head.
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| − | | |
| − | '''''Adductor Muscles'''''
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| − | | |
| − | The equine adductor muscles are formed from a short adductor and a greater adductor. They both insert along the entire medial aspect of the femur from the lesser trochanter to the medial condyles and the medial collateral stifle ligament.
| |
| − | | |
| − | '''''Internal Obturator'''''
| |
| − | | |
| − | The internal obturator originates from the cranial and medial border of the obturator foramen, the pelvic symphysis and pelvic aspect of the body of the ilium. It inserts on the trochantic fossa having passed over the lesser sciatic notch.
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| | |dragster = [[Equine Crus and Pes Surface Anatomy Resources (I, II & III)]] | | |dragster = [[Equine Crus and Pes Surface Anatomy Resources (I, II & III)]] |
| | }} | | }} |
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| | + | {{OpenPages}} |
| | + | [[Category:Muscles - Horse Anatomy]] |
