Injury to the axillary nerve is suggested by loss of sensation over which area?

• A. Lateral shoulder
• B. Medial forearm
• C. Lateral hand
• D. Posterior thigh

Answer: (A)

Injury to the axillary nerve shows up as loss of sensation over the lateral shoulder because this nerve gives a cutaneous branch (the superior lateral cutaneous nerve of the arm) that innervates the skin in the deltoid area—the region often called the regimental badge area. When that area loses sensation, it points to axillary nerve disruption. The medial forearm, lateral hand, and posterior thigh are supplied by other nerves (medial antebrachial cutaneous, radial/median nerves, and posterior femoral cutaneous nerve, respectively), so their sensory loss would suggest injuries to those nerves rather than the axillary nerve.