Canine Forelimb Anatomy

Vocabulary flashcards covering the anatomy of the canine forelimb, including extrinsic/intrinsic muscles, joint mechanics, osteology, and clinical pathologies.

Synsarcosis

The muscular attachment of the forelimb to the trunk without a bony articulation, suspending the thorax between the limbs via a muscular sling.

Weight-Bearing Rule

A kinematic principle stating that muscle action reverses based on ground contact: if the limb is fixed (weight-bearing), muscle contraction moves the trunk; if the limb is free (non-weight-bearing), muscle contraction moves the limb.

Superficial pectoral muscle

An extrinsic thoracic limb muscle originating on the first 2-3 sternebrae and inserting on the crest of the greater tubercle of the humerus, acting to adduct the limb or prevent abduction during weight bearing.

Deep pectoral muscle

An extrinsic thoracic limb muscle originating on the ventral sternum and inserting on the lesser tubercle and greater tubercle aponeurosis; it pulls the trunk cranially and extends the shoulder when fixed, or flexes the shoulder and draws the limb caudally when free.

Brachiocephalicus muscle

An extrinsic muscle divided into cleidobrachialis and cleidocephalicus (pars cervicalis and pars mastoidea) parts; it advances the free limb or draws the head and neck laterally when the limb is fixed.

Omotransversarius muscle

An extrinsic muscle attaching caudally to the distal spine of the scapula and cranially to the transverse process of the atlas; it advances the limb or flexes the neck laterally.

Trapezius muscle

An extrinsic muscle originating on the median raphe of the neck and supraspinous ligament (C3-T9) and inserting on the spine of the scapula; it elevates and abducts the forelimb.

Rhomboideus muscle

An extrinsic muscle composed of capitis, cervicis, and thoracis parts originating from the nuchal crest and T1-T7 spinous processes and inserting on the dorsal border of the scapula to elevate the limb and draw the scapula against the trunk.

Latissimus dorsi muscle

An extrinsic muscle originating on the thoracolumbar fascia and inserting on the teres major tuberosity of the humerus; it pulls the trunk cranially when the limb is fixed, or flexes the shoulder joint and draws the limb caudally when free.

Serratus ventralis muscle

A key sling muscle originating on the transverse processes of the last five cervical vertebrae and the first 7-8 ribs, inserting on the serrated face of the scapula to support the trunk and depress the scapula.

Deltoideus muscle

An intrinsic lateral scapular muscle with scapular and acromial parts originating on the spine and acromion of the scapula and inserting on the deltoid tuberosity to flex the shoulder joint.

Supraspinatus muscle

An intrinsic muscle originating in the supraspinous fossa of the scapula and inserting on the greater tubercle of the humerus, acting to extend and stabilize the shoulder joint.

Infraspinatus muscle

An intrinsic muscle originating in the infraspinous fossa and inserting on the lateral side of the greater tubercle of the humerus; it provides lateral stability and can extend or flex the shoulder joint.

Teres minor muscle

A small intrinsic lateral scapular muscle originating on the infraglenoid tubercle and inserting on the teres minor tuberosity of the humerus to flex the shoulder joint.

Subscapularis muscle

An intrinsic medial scapular muscle originating in the subscapular fossa and inserting on the lesser tubercle of the humerus to extend and stabilize the shoulder joint.

Teres major muscle

An intrinsic medial scapular muscle originating on the caudal angle and caudal border of the scapula and inserting on the teres major tuberosity of the humerus to flex the shoulder joint.

Coracobrachialis muscle

An intrinsic medial scapular muscle originating on the coracoid process of the scapula and inserting on the crest of the lesser tubercle to adduct, extend, and stabilize the shoulder joint.

Glenohumeral Joint

A ball-and-socket joint that lacks collateral ligaments and relies on active tension from active stabilizer muscles (supraspinatus, infraspinatus, subscapularis) for stability.

Triceps brachii muscle

A four-headed muscle (long, lateral, accessory, and medial) inserting on the olecranon tuber; essential for weight-bearing by maintaining extension of the elbow joint.

Anconeus muscle

A small caudal arm muscle originating on the lateral and medial epicondyles of the humerus and inserting on the lateral surface of the olecranon tuber to extend the elbow.

Tensor fasciae antebrachii muscle

A caudal arm muscle originating on the lateral side of the latissimus dorsi and inserting on the olecranon tuber to extend the elbow joint.

Biceps brachii muscle

A cranial arm muscle originating on the supraglenoid tubercle of the scapula and inserting on the ulnar and radial tuberosities to flex the elbow and extend the shoulder joint.

Brachialis muscle

A cranial arm muscle originating on the proximal third of the lateral surface of the humerus and inserting on the ulnar and radial tuberosities to flex the elbow joint.

Supinator muscle

A deep muscle of the craniolateral antebrachium originating on the lateral epicondyle of the humerus and inserting on the proximal radius to rotate the forearm laterally (supination).

Pronator teres muscle

A muscle of the caudomedial antebrachium originating on the medial epicondyle of the humerus and inserting on the medial border of the radius to rotate the forearm medially (pronation).

Extensor carpi radialis muscle

A craniolateral antebrachial muscle originating on the lateral supracondylar crest and inserting on the dorsal bases of metacarpals II and III to extend the carpal joints.

Common digital extensor muscle

A craniolateral antebrachial muscle originating on the lateral epicondyle and inserting on the extensor processes of distal phalanges II-V to extend the carpus and four principal digits.

Lateral digital extensor muscle

A craniolateral antebrachial muscle originating on the lateral epicondyle and inserting on the extensor processes of distal phalanges III-V to extend the carpus and digits III, IV, and V.

Ulnaris lateralis muscle

A craniolateral antebrachial muscle originating on the lateral epicondyle and inserting on metacarpal V and the accessory carpal bone; despite its extensor origin, it functionally flexes the carpal joints.

Superficial digital flexor muscle

A caudomedial antebrachial muscle originating on the medial epicondyle and inserting on the palmar base of middle phalanges II-V to flex the carpal, metacarpophalangeal, and proximal interphalangeal joints.

Deep digital flexor muscle

A three-headed caudomedial antebrachial muscle originating primarily on the medial epicondyle and inserting on the flexor tubercle of each distal phalanx to flex all carpal, metacarpophalangeal, and interphalangeal joints.

Flexor carpi ulnaris muscle

A caudomedial antebrachial muscle with ulnar and humeral heads that insert on the accessory carpal bone to flex the carpus.

Flexor carpi radialis muscle

A caudomedial antebrachial muscle originating on the medial epicondyle and inserting on the palmar base of metacarpals II and III to flex the carpus.

Antebrachiocarpal Joint

The most proximal articulation of the carpus between the radius/ulna and proximal carpal bones; it features an independent synovial cavity and yields the greatest range of motion in the carpal complex.

Carpal Canal

A structural tunnel bounded dorsally by the palmar carpal ligament, laterally by the accessory carpal bone, and palmarally by the flexor retinaculum, protecting the tendons of the SDF, DDF, and flexor carpi radialis.

Flexor Manica

A sleeve-like structure formed by the superficial digital flexor tendon that envelopes the deep digital flexor tendon palmar to the metacarpophalangeal joint, allowing the tendons to cross.

Dorsal elastic ligament

A connective structure attaching the middle phalanx to the distal phalanx that passively maintains the extended rest position of the distal interphalangeal joint (retracted claw position).

Infraspinatus muscle contracture

A pathological shortening and fibrotic scarring of the infraspinatus muscle following injury, causing persistent lateral rotation and abduction of the brachium along with reduced shoulder mobility.