Shoulder innervation and action

Question 1

Infraspinatus

Answer 1

Innervation: C5-C6
Suprascapular nerve
Action:
Rotator cuff muscle: ER of arm at GH joint

Question 2

Teres minor

Answer 2

Innervation: C5-C6
Axillary nerve

Action:
Rotator cuff muscle: ER of arm at GH joint

Question 3

Teres major

Answer 3

Innervation: C5-C6-C7
Inferior subscapular nerve

Action: IR and extension of arm at GH joint

Question 4

Lattissimus dorsi

Answer 4

Innervation: C6-C8
Thoracodorsal nerve

Action: Adduction, IR, and extension of arm at GH joint

Question 5

Deltoid

Answer 5

Innervation: C5-C6
Axillary nerve

Action: Major abductor of arm
Clavicular fibers assist in arm flexion
Posterior fibers assist in arm extension

Question 6

Pectoralis major

Answer 6

Flexion, adduction, and IR of arm at GH joint

Clavicular head:
Innervation: C5-C6
Medial and lateral pectoral nerves
Action: Flexion of extended arm

Sterno-costal head:
Innervation: C6-C7-C8-T1
Action: Extension of flexed arm