Extrinsic muscles of thoracic limb

Question 1

Superficial Pectoral

Answer 1

descending
Origin: first sternebra (manubrium)
insertion: crest of greater tubercle of the humerus

transverse

origin: sternebrae 1-3 and fibrous raphe on the ventral midline
insertion: crest of greater tubercle of the humerus
innervation: cranial pectoral n.
actions: adduct limb with no weight, prevent limb from being abducted when bearing weight

Question 2

deep pectoral

Answer 2

origin: sternebrae 1-8 and fibrous raphe on the ventral midline; deep abdominal fascia in the region of the xiphoid cartilage

insertion: lesser tubercle of the humerus, greater tubercle and crest of greater tubercle, medial brachial fascia
innervation: caudal pectoral n. and lateral thoracic nerve.
actions: adduct the limb, support the trunk, pull trunk cranially when limb is advanced, draw limb caudally when not bearing weight

Question 3

sternocephalicus m.

Answer 3

origin: first sternebra (manubrium)
insertion: STERNO-OCCIPITALIS (occipital part) - nuchal crest of the occipital bone of the skull

STERNOMASTOIDEUS (mastoid part) - mastoid process of the temporal bone of the skull

innervation: accessory n. and ventral brs. of cervical spinal nerve
action: draw the head and neck to the side

Question 4

sternohyoideus m.

Answer 4

origin: manubrium and first costal cartilage

insertion: basihyoid bone
innervation: ventral branches of cervical spinal nerve
action: draw the tongue and larynx caudally

Question 5

sternothyroideus m.

Answer 5

origin: first costal cartilage

insertion: caudolateral surface of the thyroid cartilage
innervation: ventral branches of cervical spinal nerve
action: draw the larynx and tongue caudally

Question 6

omotransvarius m.

Answer 6

origin: distal end of the spine of the scapula and acromion

insertion: transverse process of the first vercial vertebra; also the basioccipital bone near the tympanic bulla in the cat
innervation: accessory n.
action: advance the limb, flex the neck laterally

Question 7

trapezius m.

Answer 7

origin:
T. cervicis - median raphe of the neck (C3-C7)
T. thoracis - supraspinous ligament (T1-T9)

insertion: spine of scapula

action:
T. cervicis - draw the scapula craniodorsally
T. thoracis - draw the scapula caudodorsally
acting together - elevate and abduct the thoracic limb

Question 8

rhomboideus m.

Answer 8

Origin:
R. capitis - nuchal crest of the occipital bone
R. cervicis - median raphe of the neck
R. thoracis - spinous processes of the T1-T7 vertebrae

insertion: dorsal border and adjacent surface of the scapula
innervation: ventral brs. of cervical and thoracic spinal nerves
action: elevate the forelimb, draw scapula against the trunk

Question 9

latissimus dorsi m.

Answer 9

origin: thoracolumbar fascia from the spinous processes of T7-L7 (dog) T4-L6 (cat)
- last 2-3 ribs

insertion: teres major tuberosity of the humerus and teres major tendon
innervation: thoracodorsal n.
action: draw the limb caudally, flex the shoulder joint

Question 10

serratus ventralis m.

Answer 10

origin:
cervicis- transverse processes of C2-C7
thoracis - first 7-8 ribs (dog) first 9-10 ribs (cat)

insertion: serrated face of the scapula
innervation: long thoracic n.
action: support trunk by slinging the body between forelimbs, depress the scapula