Extrinsic Muscles of Thoracic Limb

Question 1

Superficial pectoral splits into which two muscles?

Answer 1

Descending pectoral

Transverse pectoral

Question 2

Superficial pectoral: origin

Answer 2

Origin: 1st two sternebrae; fibrous raphe btw adjacent muscles

Question 3

Superficial pectoral: insertion

Answer 3

Insertion: whole crest of the greater tubercle of the humerus

Question 4

Superficial pectoral: action

Answer 4

Action: adduct the limb when it is not bearing weight or to prevent the limb from being abducted when bearing weight

Question 5

Deep pectoral: origin

Answer 5

Origin: ventral part of the sternum; median fibrous raphe at the ventral midline

Question 6

Deep pectoral: insertion

Answer 6

Insertion: major portion partly muscular, partly tendinous on the lesser tubercle of the humerus; an aponeurosis to the greater tubercle and its crest; the caudal part to the medial brachial fascia

Question 7

Deep pectoral: action

Answer 7

Action: limb is fixed: to pull the trunk cranially and to extend the shoulder joint.
Not supporting weight: to draw the limb caudally and flex the shoulder joint

Question 8

Platysma

Answer 8

best developed of the cutaneous muscles of the neck and head

Question 9

Brachiocephalicus breaks down into which 4 muscles?

Answer 9

1) Cleidobrachialis
2) Cleidocephalicus
- –3)Pars cervicalis
- –4)Pars mastoidea

Question 10

Brachiocephalicus: origin

Answer 10

Origin: clavicular intersection

Question 11

Cleidobrachialis: attachment

Answer 11

distal end of the cranial border of the humerus

Question 12

Cleidocephalicus: attachment

Answer 12

cranial half of the mid dorsal fibrous raphe

Question 13

Pars mastoidea: attachment

Answer 13

mastoid process of the temporal bone with the sternomastoideus muscle

Question 14

Brachiocephalicus: action

Answer 14

advance the limb; to extend the shoulder joint and draw the neck and head to the side

Question 15

Sternocephalicus: action

Answer 15

Action: draw the head and neck to the side

Question 16

Omotransversarius: origin

Answer 16

Origin: wing, or transverse process, of atlas

Question 17

Omotransversarius: action

Answer 17

Action: to advance the limb or flex the neck caudally

Question 18

Trapezius: origin

Answer 18

Origin: median fibrous raphe of the neck

Question 19

Trapezius: insertion

Answer 19

Insertion: the spine of the scapula

Question 20

Trapezius: action

Answer 20

Action: to elevate and abduct the forelimb

Question 21

Rhomboideus splits into what 3 muscles?

Answer 21

1) rhomboideus capitis
2) rhomboideus cervicis
3) rhomboideus thoracis

Question 22

Rhomboideus: origin

Answer 22

1) nuchal crest of the occipital bone
2) median fibrous raphe of the neck
3) spinous processes of the first seven thoracic vertebrae

Question 23

Rhomboideus: insertion

Answer 23

Insertion: dorsal border of the adjacent surfaces of the scapula

Question 24

Rhomboideus: action

Answer 24

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

Question 25

Latissimus dorsi: origin

Answer 25

Origin: the thoracolumbar fascia from the spinous processes of the lumbar and the last seven or eight thoracic vertebrae; a muscular attachment to the last two or three ribs

Question 26

Latissimus dorsi: insertion

Answer 26

Insertion: the teres major tuberosity of the humerus and the teres major tendon

Question 27

Latissimus dorsi: action

Answer 27

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

Question 28

Serratus ventralis cervicis: origin

Answer 28

Origin: transverse process of the last five cervical vertebrae and the first seven or eight ribs ventral to their middle

Question 29

Serratus ventralis cervicis: insertion

Answer 29

Insertion: dorsomedial third of the scapula (serrated face)

Question 30

Serratus ventralis cervicis: action

Answer 30

Action: to support the trunk and depress the scapula

Question 31

Omotransversarious: Insertion

Answer 31

Insertion: distal end of scapular spine