Which nerve innervates the thenar muscles?

• A. Ulnar nerve
• B. Radial nerve
• C. Median nerve
• D. Musculocutaneous nerve

Answer: (C)

Thenar muscles—the group at the thumb base (abductor pollicis brevis, flexor pollicis brevis, and opponens pollicis)—are responsible for opposition, as well as some flexion and abduction of the thumb. Their motor supply comes from the recurrent branch of the median nerve as it enters the hand, which specifically targets these intrinsic hand muscles to enable precise thumb movements. The adductor pollicis, which is near the thenar group but not part of it, is supplied by the ulnar nerve, illustrating why the other nerves don’t control these muscles. The radial nerve serves the extensor muscles of the forearm and parts of the hand’s skin, not the thenar muscles, and the musculocutaneous nerve mainly innervates the anterior arm, not intrinsic hand muscles. So the correct nerve is the median nerve.