Nerve to the thenar compartment?

• A. Median nerve proper
• B. Recurrent branch of median nerve
• C. Ulnar nerve
• D. Radial nerve

Answer: (B)

The set of muscles in the thenar compartment (abductor pollicis brevis, flexor pollicis brevis, opponens pollicis) are supplied by a motor branch that comes off the median nerve as it enters the hand. This recurrent branch of the median nerve travels superficially to innervate the thenar muscles, enabling thumb opposition. The other nerves don’t provide this specific motor supply to the thenar eminence: the median nerve proper mainly handles forearm muscles and lateral palm sensation, the ulnar nerve chiefly provides innervation to the adductor pollicis (and most of the intrinsic hand muscles like interossei and the hypothenar group), and the radial nerve supplies the posterior/dorsal structures. So the nerve responsible for the thenar compartment is the recurrent branch of the median nerve.