Which skin area is innervated by the sensory fibers of the axillary nerve?

• A. The dorsolateral forearm
• B. The lateral arm skin over the deltoid
• C. The web space between the thumb and index finger, dorsally
• D. The palm of the hand

Answer: (B)

This question tests the sensory territory of the axillary nerve. The axillary nerve provides sensation to the skin over the lateral shoulder via the superior lateral cutaneous nerve of the arm, which covers the deltoid region (the area often called the regimental badge area).

That’s why the skin over the deltoid is the correct choice—the other regions receive sensation from different nerves: the dorsolateral forearm from the lateral antebrachial cutaneous nerve (a branch of the musculocutaneous nerve), the web space between the thumb and index dorsally from the superficial branch of the radial nerve, and the palm of the hand from branches of the median and ulnar nerves.