Extrinsic Muscles of Canine Thoracic Limb

Question 1

Deep Pectoral

Answer 1

O: ventral sternum, median fibrous raphe of at ventral midline
I: lesser tubercle of humerus and; aponeurosis to greater tubercle and its crest
A: pull trunk cranially when limb advanced and fixed, extend shoulder, draw limb caudally

Note: horse has additional pectoral muscle, subclavius muscle

Question 2

Superficial Pectoral

Answer 2

O: first 3 sternebrea; median fibrous raphe at the ventral midline
I: crest of greater tubercle of the humerus
A: adduct limb, prevent abduction when wt bearing

Note: has two parts, transverse and descending

Question 3

brachiocephalicus

Answer 3

O: clavicular intersection
I: distal end of the cranial aspect of the humerus, middorsal fabrous raphe of the neck, mastoid part of the temporal bone
A: advance the limb, extend shoulder, draw head and neck to the side

Note: two main parts: cliedobrachialis and cliedocephalicus (cervical part and mastoid part)

Question 4

Omotranservsarius

Answer 4

O: transverse process of the atlas
I: distal end of sine of the scapula
A: advance the limb, flex the neck laterally

Question 5

Trapezius

Answer 5

O: median fibrous raphe of neck, supraspinous ligament
I: spine of the scapula
A: elevate and abduct the limb at the shoulder

Question 6

Rhomboideus

Answer 6

O: nuchal crest of occipital bone, median fibrous raphe of the neck, spinous process of thoracic vertebrea
I: dorsal border of the scapula
A: elevate the limb, draw scapula against trunk

Note: muscle has 3 parts: rhombodeus capitis, rhombodeus cervicis and rhombodeus thoracis

Question 7

Latissimus dorsi

Answer 7

O: thoracolumbar fascia, last 2-3 ribs
I: teres major tuberosity of humerus
A: draw limb caudally, flex shoulder

Note: tendon joins with the tendon of teres major muscle

Question 8

Serratus Ventralis

Answer 8

O: ribs, transverse processes of cervical vertebrea
I: serrated face of scapula
A: support trunk, depress scapula

Note: cervical and thoracic parts, referred to as the “sling muscles”

Question 9

Sternocephalicus

Answer 9

O: 1st sternebra
I: mastoid part of the temporal bone and nuchal crest of occipital bone
A: draw the head and neck to the side

Note: not an extrinsic muscle but learn about them here

Question 10

Sternohyoideus

Answer 10

O: 1st stenerbra and 1st costal cartlage
I: basihyoid bone
A: pull tongue and larynx caudally

Note: not an extrinsic muscle but learn about them here

Question 11

sternothyroideus

Answer 11

O: 1st costal cattilage
I: caudolateral surface of thyroid cartilage
A: draw the larynx and tongue caudally

Note: not an extrinsic muscle but learn about them here