Action:  Shoulder extension

Nerves:  Axillary, thoracodorsal, and subscapular

Skeletal muscles:  Deltoid, latissimus dorsi, and teres major

Cutaneous distribution:  None except for the axillary nerve

Neuromuscular deficit:  Weakness/paralysis when extending at the shoulder joint under resistance. Denervation is accompanied by muscular atrophy and deficit along the cutaneous distribution of the axillary (superior lateral brachial cutaneous) nerve.

Differential diagnosis:  Extensor weakness/paralysis that is accompanied by cutaneous nerve deficit is diagnostic of axillary nerve impairment as the thoracodorsal and subscapular nerves have no distribution in the skin.