The Back (Extrinsic muscle actions & innervations)

Question 1

Latissimus dorsi (A & Inn)

Answer 1

A: extends, adducts, and medially rotates humerus, raises torso towards arms during climbing

Inn: thoracodorsal nerve

Question 2

Rhomboid major & minor (A & Inn)

Answer 2

A: Both retract, elevate, and rotate scapula downward, as well as fix it to thoracic wall

Inn: Both are innervated by the dorsal scapular nerve

Question 3

Lavator scapulae (A & Inn)

Answer 3

A: elevates scapula and tilts glenoid fossa inferiorly by rotating scapula (downward rotation)

Inn: dorsal scapular nerve and ventral rami of cervical spinal nerves C3-C4

Question 4

Serratus posterior superior (A & Inn)

Answer 4

A: elevates ribs

Inn: T2-T5 intercostal nerves from ventral rami

Question 5

Serratus posterior inferior (A & Inn)

Answer 5

A: depress ribs

Inn: intercostal nerves & subcostal nerve (ventral rami)

Question 6

Trapezius (A & Inn)

Answer 6

A: elevates, depresses, and retracts scapula, rotates glenoid fossa superiorly

Inn:
Motor= accessory nerve
Sensory= ventral rami of C3 & C4