Veterinary Anatomy Lab #1: Dog Thoracic Limb OIA

What are the intrinsic muscles of the thoracic limb?

1. Lateral muscles of the shoulder (suprascapular and axillary nn)

2. Medial muscles of the shoulder (subscapular, axillary, and musculocutaneous nn.)

3. Cranial Muscles of the Brachium (musculocutaenous n.)

4. Caudal muscles of the Brachium (radial n.)

5. Craniolateral Antebrachial muscles (radial n.)

6. Caudomedial Antebrachial muscles (median and ulnar nn.)

7. Muscles of the manus

What are the lateral muscles of the shoulder?

1. Deltoideus m.

2. Supraspinatus m.

3. Infraspinatus m.

4. Teres minor m.

What nerves innervate the lateral muscles of the shoulder?

- Suprascapular nerve

- Axillary nerve

What is the origin of the deltoideus m.?

- Spine of scapula and acromion

What is the insertion point of the deltoideus m.?

- Deltoid tuberosity of the humerus

What is the action of the deltoideus m?

- Flex the humeral joint

What is the origin of the supraspinatus muscle?

- Supraspinatus fossa of the scapula

What is the insertion site of the supraspinatus muscle?

- Greater tubercle of the humerus

What is the action of the supraspinatus muscle?

- Laterally stabilize humeral joint, extend the humeral joint

What is the origin of the infraspinatus muscle?

- infraspinous fossa of scapula

What is the insertion of the infraspinatus muscle?

- greater tubercle of humerus

What is the action of the infraspinatus muscle?

- laterally stabilize the humeral joint

What is the origin of the teres minor muscle?

- Caudal border of the scapula

What is the insertion of the teres minor muscle?

- Teres minor tuberosity of the humerus

What is the action of the teres minor muscle?

- Flex the humeral joint

What are the medial muscles of the shoulder?

1. Subscapularis m.

2. Teres major m.

3. Coracobrachialis m.

What nerves innervate the medial muscles of the shoulder?

- Subscapular nerve

- Axillary nerve

- Musculocutaneous nerve

What is the origin of the subscapularis muscle?

- Subscapular fossa of the scapula

What is the insertion of the subscapularis muscle?

- lesser tubercle of the humerus

What is the action of the subscapularis muscle?

- Medially stabilize the humeral joint

What is the origin of the teres major muscle?

- caudal border of scapula

What is the insertion of the teres major muscle?

- Teres major tuberosity of the humerus

What is the action of the teres major muscle?

flex the humeral joint

What is the origin of the coracobrachialis muscle?

coracoid process of scapula

What is the insertion of the coracobrachialis muscle?

crest of the lesser tubercle of the humerus

What is the action of the coracobrachialis muscle?

- Medially stabilize the humeral joint

What are the cranial muscles of the brachium?

1. Biceps brachii m. (only one head in domestic mammals)

2. Brachialis m.

What nerves innervate the cranial muscles of the brachium?

- musculocutaneous n.

What is the origin of the biceps brachii muscle?

- supraglenoid tubercle of the humerus

What is the insertion of the biceps brachii muscle?

- radial tuberosity (and ulnar tuberosity in dogs)

What is the action of the biceps brachii muscle?

- flex the cubital joint

- extend the humeral joint

What is the origin of the brachialis muscle?

brachial groove of humerus

What is the insertion of the brachialis muscle?

proximal radius and/or ulna

What is the action of the brachialis muscle?

- flex the cubital joint

What are the caudal muscles of the brachium?

- Triceps brachii muscle

*long, medial, and lateral heads in all species

*carnivores also have an accessory head

- Tensor fasciae antebrachii muscle

- Anconeus muscle

What nerves innervate the caudal muscles of the brachium?

- radial nerve

What is the origin of the triceps brachii muscle?

- caudal border of scapula (long head)

- proximal humerus (other heads)

What is the insertion of the triceps brachii muscle?

- tuber olecrani

What is the action of the triceps brachii muscle?

- extend the cubital joint (all heads)

- flex the humeral joint (long head only)

What is the origin of the tensor fasciae antebrachii muscle?

- latissimus dorsi and associated fascia

What is the insertion of the tensor fasciae antebrachii muscle?

- tuber olecrani

What is the action of the tensor fasciae antebrachii muscle?

- extend the cubital joint (and tense the deep antebrachial fascia)

What is the origin of the anconeus muscle?

- caudal aspect of distal humerus

What is the insertion of the anconeus muscle?

- tuber olecrani

What is the action of the anconeus muscle?

- extend the cubital joint

What do the craniolateral antebrachial muscles consist of?

- extensor carpi radialis muscle

- common digital extensor muscle

- lateral digital extensor muscle

- ulnaris lateralis muscle

- supinator muscle

- abductor digiti I longus muscle

- brachioradialis muscle (better developed in a cat)

What nerve innervates craniolateral antebrachial muscles?

- radial nerve

What is the origin of the extensor carpi radialis muscle?

- lateral epicondyle of the humerus (and its crest)

What is the insertion of the extensor carpi radialis muscle?

- dorsal base of 2nd and 3rd metacarpal bones

What is the action of the extensor carpi radialis muscle?

- extend the carpal joints

What is the origin of the common digital extensor muscle?

- lateral epicondyle of the humerus

What is the insertion of the common digital extensor muscle?

- extensor processes of distal phalanges

What is the action of the common digital extensor muscle?

- extend the carpal joints

- extend the digital joints

What is the origin of the lateral digital extensor muscle?

- lateral epicondyle of the humerus

What is the insertion of the lateral digital extensor muscle?

- phalanges of the lateral-most digits

What is the action of the lateral digital extensor muscle?

- extend the carpal joints

- extend the digital joints of the lateral-most joints

What is the origin of the ulnaris lateralis muscle?

- lateral epicondyle of the humerus

What is the insertion of the ulnaris lateralis muscle?

- accessory carpal bone

- lateral base of 5th metacarpal bone

What is the action of the ulnaris lateralis muscle?

- awkwardly flex the antebrachiocarpal joint

- abduct the manus

What is the origin of the supinator muscle?

- lateral epicondyle of the humerus

What is the insertion of the supinator muscle?

- body of radius

What is the action of the supinator muscle?

- supination of the manus

What is the origin of the abductor digiti I longus muscle?

- Body of the ulna (in the carnivore)

What is the insertion of the abductor digiti I longus muscle?

- base of 1st metacarpal bone

What is the action of the abductor digiti I longus muscle?

- abduct the 1st digit

What is the origin of the brachioradialis muscle?

- lateral epicondyle of the humerus

What is the insertion of the brachioradialis muscle?

- fascia near the carpus

What is the action of the brachioradialis muscle?

- supination of the manus

What are the caudomedial antebrachial muscles?

- flexor carpi radialis m.

- flexor carpi ulnaris m. (2 heads: humeral and ulnar)

- Superficial digital flexor muscle

- Deep digital flexor muscle (3 heads: humeral, radial, ulnar)

- Pronator teres muscle

- Pronator quadratus muscle

What nerves innervate the caudomedial antebrachial muscles?

- median n.

- ulnar n.

What is the origin of the flexor carpi radialis muscle?

- medial epicondyle of the humerus

What is the insertion of the flexor carpi radialis muscle?

- palmar base of 2nd and 3rd metacarpal bones

What is the action of the flexor carpi radialis muscle?

- flex the carpal joints

What is the origin of the flexor carpi ulnaris muscle?

- medial epicondyle of the humerus

- olecranon of the ulna

What is the insertion of the flexor carpi ulnaris muscle?

- accessory carpal bone

What is the action of the flexor carpi ulnaris muscle?

- flex the antebrachiocarpal joint

What is the origin of the superficial digital flexor muscle?

- medial epicondyle of the humerus

What is the insertion of the superficial digital flexor muscle?

- palmar bases of the middle phalanges

What is the action of the superficial digital flexor muscle?

- flex the carpal joints

- flex the metacarpophalangeal joints

- flex the proximal interphalangeal joints

What is the origin of the deep digital flexor muscle?

- medial epicondyle of the humerus

- body of the radius

- body of the ulna

What is the insertion of the deep digital flexor muscle?

- flexor tubercles of the distal phalanges

What is the action of the deep digital flexor muscle?

- flex the carpal joints

- flex the digital joints

What is the origin of the pronator teres muscle?

- medial epicondyle of the humerus

What is the insertion of the pronator teres muscle?

- body of radius

What is the action of the pronator teres muscle?

- pronation of the manus

What are the attachments of the pronator quadratus muscle?

- apposed surfaces of the radius and the ulna

What is the action of the pronator quadratus muscle?

- pronation of the manus

What are the muscles of the manus?

- Interossei mm. (associated with proximal sesamoid bones)

What is the origin of the interossei mm.?

- palmar base of respective metacarpal bone

What is the insertion of the interossei mm.?

- proximal sesamoid bones & palmar base of respective proximal phalanx (tendon of common digital extensor dorsally via extensor branch)

What is the action of the interossei mm.?

- supports and flex metacarpophalangeal joint

What are the extrinsic muscles of the thoracic limb?

- superficial pectoral muscle (descending and transverse pectoral muscles)

- deep (ascending) pectoral muscle

- brachiocephalicus muscle

- omotransversarius muscle

- trapezius muscle

- rhomboideus muscle

- serratus ventralis muscle

- latissimus dorsi muscle

What is the origin of the superficial pectoral muscle?

- cranial part of sternum

What is the insertion of the superficial pectoral muscle?

- crest of greater tubercle

- cranial humeral border (ulna in cat)

What is the action of the superficial pectoral muscle?

- adduct thoracic limb

What is the origin of the deep (ascending) pectoral muscle?

- sternum

What is the insertion of the deep (ascending) pectoral muscle?

- greater tubercle of humerus

- lesser tubercle of humerus

What is the action of the deep (ascending) pectoral muscle?

- adduct thoracic limb and pull it caudally

What is the origin of the brachiocephalicus muscle?

- clavicular insertion / clavicle

What are the different muscles/parts associated with the insertion of the brachiocephalicus muscle?

- cleidobrachialis muscle

- cleidocephalicus muscle:

*mastoid part

*cervical part