Thoracic Limb Muscles-Muscle to Details Flashcards
Superficial pectoral
Origin: first three sternebrae; median fibrous raphe at the ventral midline
Insertion: crest of the greater tubercle of the humerus
Action: adduct the limb when not weight bearing; prevent abduction of the limb when weight bearing
transverse and descending parts
Deep pectoral
Origin: ventral part of sternum; median fibrous raphe at the ventral midline
Insertion: lesser tubercle of the humerus (major portion); greater tubercle and crest of the humerus via aponeurosis
Action: pull trunk cranially when limb is advanced; extend shoulder; draw limb caudally when not weight bearing
Brachiocephalicus
Origin: clavicular intersection
Insertion: distal end of cranial humerus (cleidobrachialis); middorsal fibrous raphe of the neck (cleidocervicalis of the cleidocephalicus); mastoid part of the temporal bone (cleidomastoideous of the cleidocephalicus)
Action: advance the limb; extend shoulder; draw head and neck to the side
Omotransversarius
Origin: wing of the atlas (cervical vertebra 1)
Insertion: distal end of the spine of the scapula
Action: advance the limb; flex the neck laterally
has the superficial cervical lymph node deep to it
Trapezius
Origin: median fibrous raphe of the neck; supraspinous ligament
Insertion: spine of the scapula
Action: elevate and abduct the limb
cervical and thoracic parts
Rhomboideous
Origin: base of the skull (capitis); median fibrous raphe of the neck (cervicis); spinous processes of thoracic vertebrae (thoracis)
Insertion: dorsal border of scapula
Action: elevate the limb; draw scapula against trunk
Lastissimus dorsi
Origin: thoracolumbar fascia; last few ribs
Insertion: teres major tuberosity of the humerus via the teres major tendon
Action: draw limb caudally; flex shoulder
Serratus ventralis
Origin: ribs; transverse processes of cervical vertebrae
Insertion: serrated face of the scapula
Action: support trunk; depress scapula
often referred to as the sling muscle; has cervical and thoracic parts
Deltoideous
Origin: spine and acromion of the scapula
Insertion: deltoid tuberosity of the humerus
Action: flex shoulder
Infraspinatus
Origin: infraspinous fossa of the scapula
Insertion: lateral side of the greater tubercle of the humerus
Action: laterally stabilizes the shoulder (prevent medial rotation when weight bearing); abduct and laterally rotate shoulder; assists in extension or flexion of the shoulder
has a subtendinous bursa
Teres minor
Origin: infraglenoid tubercle of scapula; distal caudal border of scapula
Insertion: teres minor tuberosity of the humerus
Action: laterally stabilizes the shoulder (prevent medial rotation when weight bearing); laterally rotate shoulder; flex shoulder
Supraspinatous
Origin: supraspinous fossa of the scapula
Insertion: greater tubercle of the humerus via a thick tendon
Action: laterally stabilizes the shoulder (prevent medial rotation when weight bearing); extend shoulder
Subscapularis
Origin: subscapular fossa of the scapula
Insertion: lesser tubercle of the humerus
Action: medially stabilizes the shoulder (prevent lateral rotation when weight bearing); adduct shoulder; extend shoulder
Teres major
Origin: caudal angle and border of the scapula; subscapularis muscle
Insertion: trees major tuberosity of the humerus
Action: flex shoulder; rotate limb medially
Coracobrachialis
Origin: coracoid process of the scapula
Insertion: crest of the lesser tubercle of the humerus; near the teres major tuberosity
Action: shoulder stabilizer
Tensor fascia antebrachii
Origin: fascia covering the lateral surface of the latissimus dorsi muscle
Insertion: olecranon of the ulna
Action: extend elbow
Triceps brachii
Origin: caudal border of scapula (long head); tricipital line and proximal humerus (lateral, medial and accessory heads)
Insertion: olecranon of the ulna
Action: flex shoulder (long head); extend elbow (all heads)
Anconeous
Origin: lateral supracondylar crest of the humerus; lateral and medial epicondyles of the humerus
Insertion: proximal and lateral aspects of the ulna
Action: extend elbow
Biceps brachii
Origin: supraglenoid tubercle of the scapula
Insertion: radial and ulnar tuberosities
Action: extend shoulder; flex elbow
- has transverse humeral retinaculum, tendon of origin, and subtendinous bursa*
- lacertus fibrosus of horse is the long tendon of the biceps brachii associated with the stay apparatus*
Brachialis
Origin: brachialis groove of the humerus
Insertion: radial and ulnar tuberosities
Action: flex elbow
Extensor carpii radialis
Origin: lateral supracondylar crest of the humerus
Insertion: metacarpal tuberosities (dorsal aspect) of MC II and III
Action: extend carpus
Common digital extensor
Origin: lateral epicondyle of the humerus
Insertion: extensor processes (bases) of the distal phalanges II-V
Action: extend carpus and digits
Lateral digital extensor
Origin: lateral epicondyle of the humerus
Insertion: extensor processes (bases) of the distal phalanges III-V
Action: extend carpus and digits
Ulnaris lateralis
Origin: lateral epicondyle of the humerus
Insertion: lateral aspect of the base of MC V; accessory carpal bone
Action: abduct the carpus; flex carpus
Supinator
Origin: lateral epicondyle of the humerus
Insertion: cranial aspect of the proximal radius
Action: supination
not present in large animals
Pronator teres
Origin: medial epicondyle of the humerus
Insertion: medial border of the radius
Action: pronation
not present in large animals
Abductor pollicis longus
Origin: lateral and cranial border of the ulna; interposes membrane between the radius and ulna
Insertion: proximal end of MC I
Action: abduct digit I
Flexor carpi radialis
Origin: medial epicondyle of the humerus; medial border o the radius
Insertion: palmar surface of base of MC II and III
Action: flex carpus
Superficial digital extensor
Origin: medial epicondyle of the humerus
Insertion: palmar surface of the bases of middle phalanges II-V
Action: flex carpus and digits
- flexor manica where the DDF and SDF switch orientations*
- annular ligaments hold down the tendons of the SDF and DDF*
- horse has the proximal check ligament from caudal and distal aspect of the radius to the tendon of SDF*
Flexor carpi ulnaris
Origin: medial epicondyle of the humerus; caudal and medial aspect of the olecranon
Insertion: accessory carpal bone
Action: flex carpus
has ulnar and humeral heads
Deep digital flexor
Origin: medial epicondyle of the humerus; ulna; radius
Insertion: flexor tubercle of the distal phalanx of each digit
Action: flex carpus and digits
- has radial, humeral and ulnar heads which all converge within the carpal canal as the DDF tendon*
- horse has the distal check ligament from proximal and palmar aspect of MC III to the tendon of the DDF*
Pronator quadratus
Origin/Insertion: located within the space between the radius and ulna
Action: pronate the antebrachium
not present in large animals
Interosseous
Origin/Insertion: lie deep to the DDF tendons and cover the palmar surfaces of the four main MC bones; there are two proximal sesamoid bones embedded in the tendon of insertion of each interosseous muscles
- in horse, there is only one, and it is called the suspensory ligament; it has medial and lateral extensor branches*
- there are three pairs of sesmoidean ligaments: straight, oblique and cruciate*
