Forelimb

Question 1

Extrinsic Muscle:

Superficial Pectoral Muscle

Answer 1

2 parts - transverse and descending (smaller and superficial to transverse)
Origin: first 2 sternebrae (& part of 3)
Insertion: crest of greater tubercle (cranial edge of humerus)
Action: adduction (NWB) or prevent abduction (WB)
Innervation: cranial pectoral nerves

Question 2

Extrinsic Muscle:

Deep Pectoral Muscle

Answer 2

Larger and longer than superficial. Lies under skin and ventral part of cutaneous trunci
Origin: ventral part of sternum
Insertion: lesser tubercle. Aponeurosis (thin tendonous sheet) to greater tubercle
Action: pull trunk cranially and extend shoulder when limb advanced. NWB draw limb caudally and flex shoulder. Adduct limb.
Innervation: cranial pectoral nerves

Question 3

Extrinsic Muscle:

Braciocephalicus - cleidobrachialis

Answer 3

Distal to the clavicular intersection (fibrous plate)
Origin: clavicular intersection
Insertion: distill end of cranial humerus
Action: advance limb, extend shoulder joint.
Innervation: accessory nerve

Question 4

Extrinsic Muscle:

Brachiocephalicus - cleidomastoideus

Answer 4

Thicker part of cleidocephalicus runs towards head
Origin: clavicular intersection
Insertion: mastoid process of temporal bone
Action: draw head and neck to one side.
Innervation: cervical spinal nerves

Question 5

Extrinsic Muscle:

Brachiocephalicus - cleidocervicalis

Answer 5

Thinner part of cleidocephalicus runs towards neck, bound by trapezius.
Origin: clavicular intersection
Insertion: dorsal midline of neck (& nuchal crest of occipital bone)
Action: draw head and neck to one side.
Innervation: cervical spinal nerves

Question 6

Extrinsic Muscle:

Omotransversarius

Answer 6

Strap like. Caudally subcutaneous, cranially covered by cleidocervicalis.
Origin: atlas vertebrae (traverse wing)
Insertion: distal end of scapular spine
Action: advance limb / lateral neck flex
Innervation: Accessory nerve

Question 7

Extrinsic Muscles:

Trapezius

Answer 7

Thin triangular muscle. Cervical and thoracic parts separated by aponeurosis.
Origin: median raphe of neck and supraspinous ligament from C3-T9.
Insertion: spine of scapular
Action: elevate and abduct forelimb
Innervation: accessory nerve

Question 8

Extrinsic Muscles:

Rhomboideus

Answer 8

Lies deep to trapezius.
Origin: nuchal crest, median raphe of neck, spinous processes of T1-T7
Insertion: dorsal boarder of scapular
Action: elevate forelimb, adduct scapular against trunk
Innervation:cervical and thoracic spinal nerves

Question 9

Extrinsic Muscles:

Latissimus Dorsi

Answer 9

Large triangular muscle caudal to scapular. Covers dorsal thoracic wall.
Origin: fascia on spinous processes of last 7 thoracic and lumbar vertebrae.
Insertion: teres major tuberosity of humerus & teres major tendon. Medial
Action: flex shoulder, draw NWB limb caudally
Innervation: thoracodorsal nerve

Question 10

Extrinsic Muscles:

Serratus Ventralis

Answer 10

Large, fan shaped. Acts as sling to support trunk.
Origin: transverse processes of last 5 cervical vertebrae & first 7-8 ribs
Insertion: serrated face of scapular
Action: support trunk, depress scapular
Innervation: cervical spinal nerves & long thoracic nerve.