Intrinsic Muscles of the Thoracic Limb Flashcards
deltoideus m.
O: spine and acromion of the scapula
I: deltoid tuberosity of the humerus
Action: flex the shoulder
horses only have one part since they do not have an acromion*
infraspinatus m.
O: infraspinous fossa of the scapula
I: lateral side of the greater tubercle of the humerus
Action: extend the shoulder; stabilize the shoulder laterally (prevent medial rotation); abduct and laterally rotate the shoulder
*subtendinous synovial bursa
supraspinatus m.
O: supraspinous fossa of the scapula
I: greater tubercle of the humerus
Action: stabilize shoulder laterally (prevent medial rotation); shoulder extensor
teres minor m.
O: infragelnoid tubercle of the scapula; distal caudal border of the scapula
I: teres minor tuberosity of the humerus
Action: flex the shoulder; stabilize and rotate shoulder laterally
subscapularis m.
O: subscapular fossa of the scapula
I: lesser tubercle of the humerus
Action: stabilize medially; extend shoulder; adduct shoulder
teres major m.
O: caudal border and angle of the scapula; subscapularis muscle
I: teres major tuberosity
Action: rotate shoulder medially; extend shoulder
What muscles act as shoulder extensors?
- infraspinatus m.
- supraspinatus m.
- subscapularis m.
- coracobrachialis m.
- biceps brachii m.
What muscles act as shoulder flexors?
- teres minor m.
- teres major m.
- deltoideus m.
- long head of triceps brachii m.
coracobrachialis
O: coracoid process of scapula
I: crest of lesser tubercle; near teres major tuberosity
Action: shoulder stabilizer
tensor fasciae antebrachii
O: fascia covering the lateral surface of the latissimus dorsi
I: olecranon of ulna; in common with tendon of insertion of the triceps brachia
Action: extend elbow
triceps brachii
O: caudal border (long head); proximal humerus and tricipital line (other head)
I: olecranon of ulna
Action: extend elbow (all heads) and flex shoulder (long head)
anconeus
O: lateral supracondylar crest of the humerus; lateral and medial epicondyle of the humerus
I: proximal and lateral aspect of the ulna
Action: extend elbow
biceps brachii
O: supraglenoid tubercle of scapula
I: radial and ulnar tuberosities
Action: flex elbow; extend shoulder
brachialis
O: brachialis groove (proximal and lateral aspect of humerus)
I: radial and ulnar tuberosities
Action: flex elbow
extensor carpi radialis
O: lateral supracondylar crest of the humerus
I: metacarpal tuberosities of MC II and III
Action: extend carpus
***Horse: inserts at MC III
common digital extensor
O: lateral epicondyle of the humerus
I: extensor processes of the distal phalanx of digits 2, 3, 4, and 5.
Action: extend the joints of digits 2, 3, 4, and 5
Lateral digital extensor and lateral and medial extensor branches of the interosseous converge with common digital extensor in the horse!!!
lateral digital extensor
O: lateral epicondyle of the humerus
I: extensor processes of the distal phalanx of digits 3, 4, and 5
Action: extend the joints of digits 3, 4, and 5
ulnaris lateralis
O: lateral epicondyle of the humerus
I: lateral aspect of the proximal end of MC V; accessory carpal bone
Action: flex carpus; abduct carpus
supinator
O: lateral epicondyle of the humerus
I: cranial aspect of the proximal radius
Action: supination (rotating antebrachium laterally, so the palmar surface of paw faces medially)
pronator teres
O: medial epicondyle of humerus
I: medial border of the radius
Action:pronation (rotate antebrachium medially so that palmar surface of paw faces ground)
flexor carpi radialis
O: medial epicondyle of the humerus
I: palmar surface of proximal aspect of MC II and III
superficial digital flexor
O: medial epicondyle of humerus
I: palmar surface of proximal aspect of middle phalanges of digits 2, 3, 4, and 5
Action: flex carpus; flex digits 2, 3, 4, and 5
flexor carpi ulnaris
O: medial epicondyle of humerus; olecranon
I: accessory carpal bone
Action: flex carpus
deep digital flexor
O: medial epicondyle of humerus; radius; ulna
I: flexor tubercle of distal phalanx of each digit
Action: flex carpus; flex digits
What are the borders of the carpal canal?
Dorsal: palmar carpal ligament
Lateral:accessory carpal bone
Palmar: flexor retinaculum
What muscles are present in the carpal canal?
Dog:
- flexor carpi radialis
- deep digital flexor
Horse:
- superficial digital flexor
- deep digital flexor
- flexor carpi radialis
