Thoracic Limb O, I, A

Question 1

Superficial Pectoral

Answer 1

Origin: The first 2 sternebrae and usually part of the 3rd; the fibrous raphe between adjacent muscles.
Insertion: Greater tubercle of the humerus.
Action: To adduct the limb when not bearing weight or to prevent the limb from being abducted when bearing weight.

Question 2

Deep Pectoral

Answer 2

“Origin: Ventral part of sternum and the fibrous raphe; the deep abdominal fascia in the region of the xiphoid cartilage (the caudal end of sternum)
Insertion: Lesser tubercle of humerus; aponeurosis to greater tubercle and its crest; caudal part of the medial brachial fascia

Action: When the limb is advanced and fixed: to pull the trunk cranially and extend the shoulder joint. When the limb is not supporting weight: to draw the limb caudally and flex the shoulder joint. To adduct the limb.”

Question 3

Brachiocephalicus

Answer 3

“Attachments: All are movable. Origin: Clavicle or Clavicular intersection.
Cleidobrachialis: attaches to the distal end of the cranial border of the humerus. Also significant fascial tie into the axilla.

Cervical Cleidocephalicus: attached to cranial half of mid-dorsal fibrous raphe and sometimes to nuchal crest of the occipital bone.

Mastoid Cleidocephalicus: attaches to mastoid process of the temporal bone with the sternomastoideus muscle.

Action: To advance the limb; to extend the shoulder joint and draw the neck and head to the side.”

Question 4

Sternocephalicus

Answer 4

“Origin: The first sternebra or manubrium.
Insertion: Mastoid part of the temporal bone and nuchal crest of the occipital bone.

Action: To draw the head and neck to the side.”

Question 5

Sternohyoideus

Answer 5

“Origin: The first sternebra and the first costal cartilage
Insertion: The basihyoid bone.

Action: To pull the tongue and larynx caudally.”

Question 6

Sternothyroideus

Answer 6

“Origin: First costal cartilage.
Insertion: The caudolateral surface of the thyroid cartilage.

Action: To draw larynx and tongue caudally.”

Question 7

Omotransversarius

Answer 7

“Attachments: The distal end of the spine of the scapula; cranially, the transverse wing of the atlas.
Action: To advance the limb or flex the neck laterally.”

Question 8

Trapezius

Answer 8

“Origin: Median raphe of the neck and the supraspinous ligament from the level of the third cervical vertebra to the level of the ninth thoracic vertebra.
Insertion: Spine of scapula

Action: To elevate and abduct the forelimb.”

Question 9

Rhomboideus

Answer 9

“Origin: Nuchal crest of the occipital bone; the median fibrous raphe of the neck; the spinous processes of the first 7 thoracic vertebrae.
Insertion: The dorsal border and adjacent surfaces of the scapula.

Action: To elevate the forelimb and draw the scapula against the trunk.”

Question 10

Latissimus Dorsi

Answer 10

“Origin: The thoracolumbar fascia from the spinous processes of the lumbar and the last 7 or 8 thoracic vertebrae. Muscular attachment to last 2-3 ribs.
Insertion: The teres major tuberosity of the humerus and the teres major tendon.

Action: To draw the free limb caudally as in digging; to flex the shoulder joint.”

Question 11

Serratus ventralis cervicis/Serratus ventralis thoracis

Answer 11

“Origin: Transverse processes of the last 5 cervical vertebrae and the first 7-8 ribs ventral to their middle.
Insertion: Dorsomedial third of the scapula (serrated face)

Action: To support the trunk and depress the scapula.”

Question 12

Deltoideus

Answer 12

“Origin: Spine and acromial process of the scapula.
Insertion: The deltoid tuberosity

Action: To flex the shoulder.”

Question 13

Infraspinatous

Answer 13

“Origin: Infraspinous fossa
Insertion: Small, circumscribed area on the lateral side of the greater tubercle of the humerus

Action: To extend and laterally stabilize or flex the shoulder joint, depending on the degree of extension or position of the joint where the muscle contracts. To abduct the shoulder joint and rotate the shoulder laterally. To prevent medial rotation when weight bearing and provide lateral stability to the shoulder joint.”

Question 14

Teres minor

Answer 14

“Origin: Infraglenoid tubercle and distal third of the caudal border of the scapula
Insertion: The teres minor tuberosity of the humerus.

Action: To flex the shoulder joint, rotate the shoulder laterally and prevent medial rotation when bearing weight.”

Question 15

Supraspinatous

Answer 15

“Origin: Supraspinous fossa
Insertion: Greater tubercle of the humerus (by a thick tendon)

Action: To extend and laterally stabilize the shoulder joint.”

Question 16

Subscapularis

Answer 16

“Origin: Subscapular fossa
Insertion: Lesser tubercle of humerus

Action: To adduct, extend and medially stabilize the shoulder joint. To rotate the shoulder medially and prevent lateral rotation when weight bearing”

Question 17

Teres major

Answer 17

“Origin: Caudal angle and adjacent caudal border of the scapula; the caudal surface of the subscapularis
Insertion: Teres major tuberosity of humerus

Action: Flex the shoulder, rotate the shoulder medially and prevent lateral rotation when weight bearing.”

Question 18

Coracobrachialis

Answer 18

“Origin: Coracoid process of scapula
Insertion: Crest of lesser tubercle of humerus proximal to the teres major tuberosity.

Action: To adduct, extend and stabilize the shoulder joint.”

Question 19

Tensor fasciae antebrachii

Answer 19

“Origin: Fascia covering the lateral side of the latissimus dorsi
Insertion: The olecranon

Action: To extend the elbow”

Question 20

Triceps brachii: Long Head

Answer 20

“Origin: Caudal border of scapula
Insertion: The olecranon tuber

Action: To extend the elbow and flex the shoulder.”

Question 21

Triceps brachii: Lateral Head

Answer 21

“Origin: Tricipital line of humerus
Insertion: Olecranon Tuber

Action: To extend the elbow”

Question 22

Triceps brachii: Accessory head

Answer 22

“Origin: Neck of humerus
Insertion: Olecranon tuber

Action: To extend the elbow”

Question 23

Triceps brachii: Medial Head

Answer 23

“Origin: The crest of the lesser tubercle near the teres major tuberosity
Insertion: Olecranon

Action: To extend the elbow.”

Question 24

Anconeus

Answer 24

“Origin: Lateral supracondylar crest and the lateral and medial epicondyles of the humerus
Insertion: Lateral surface of the proximal end of the ulna (olecranon)

Action: To extend the elbow”

Question 25

Biceps brachii

Answer 25

“Origin: Supraglenoid tubercle
Insertion: Ulnar and radial tuberosities

Action: To flex the elbow and extend the shoulder”

Question 26

Brachialis

Answer 26

“Origin: The proximal third of the lateral surface of the humerus
Insertion: Ulnar and radial tuberosities

Action: To flex the elbow”

Question 27

Extensor carpi radialis

Answer 27

“Origin: Lateral supracondylar crest
Insertion: Small tuberosities on the doral surfaces of the base of metacarpals II and III

Action: To extend the carpus”

Question 28

Common digital extensor

Answer 28

“Origin: Lateral epicondyle of the humerus
Insertion: The extensor processes of the distal phalanges of digits II, III, IV and V

Action: To extend the joints of the four principal digits and the carpus.”

Question 29

Lateral Digital Extensor

Answer 29

“Origin: Lateral epicondyle of the humerus
Insertion: Proximal ends of all the phalanges of digits III, IV and V but mainly the extensor processes of the distal phalanges of these digits

Action: To extend the carpus and joints of digits III, IV, and V”

Question 30

Ulnaris lateralis

Answer 30

“Origin: Lateral epicondyle of the humerus
Insertion: Lateral aspect of the proximal end of metacarpal V and the accessory carpal bone

Action: To abduct the manus and flex the carpal joint and support the carpus when extended to support weight.”

Question 31

Supinator

Answer 31

“Origin: Lateral epicondyle of humerus
Insertion: Cranial surface of the proximal fourth of the radius

Action: To rotate the forearm laterally so that the palmar side of the paw faces medially (supination); to flex the elbow.”

Question 32

Abductor digiti I longus

Answer 32

“Origin: Lateral border and cranial surface of the body of the ulna; the interosseous membrane
Insertion: Proximal end of metacarpal I

Action: To abduct the first digit or pollex and extend the carpal joints”

Question 33

Pronator Teres

Answer 33

“Origin: The medial epicondyle of the humerus
Insertion: Medial border of the radius between the proximal and middle thirds

Action: To rotate the forearm medially so that the palmar side of the paw faces the ground (pronation); to flex the elbow”

Question 34

Flexor carpi radialis

Answer 34

“Origin: Medial epicondyle of the humerus and the medial border of the radius
Insertion: Palmar side of the base of metacarpals II and III

Action: To flex the carpus”

Question 35

Superficial Digital flexor

Answer 35

“Origin: Medial epicondyle of humerus
Insertion: Palmar surface of the base (proximal end) of the middle phalanges of digits II, III, IV and V

Action: To flex the carpal, metacapophalangeal and proximal interphalangeal joints of digits II, III, IV and V”

Question 36

Flexor carpi ulnaris

Answer 36

“Origin: Ulnar Head - the caudal border and medial surface of the olecranon; humeral head - the medial epicondyle of the humerus
Insertion: The accessory carpal bone.

Action: To flex the carpus.”

Question 37

Deep digital flexor

Answer 37

“Origin: Humeral head - the medial epicondyle of the humerus; ulnar head - the proximal 3/4 of the caudal border of the ulna; radial head - the middle third of the medial border of the radius
Insertion: the flexor tubercle on the palmar surface of the distal phalanx of each digit

Action: To flex the carpal and metacarpophalangeal joints and the proximal and distal interphalangeal joints of the digits.”

Question 38

Pronator quadratus

Answer 38

“Attachments: The apposed surfaces of the radius and ulna

Action: To pronate the paw.”