In median nerve compression at the wrist, which sensory area is affected earliest?

• A. Dorsal surface of the hand
• B. Palmar surface of the thumb, index, middle, and radial half of ring finger
• C. Palmar surface of little finger
• D. Dorsal surface of the index finger

Answer: (B)

Understanding sensory distribution is key. At the wrist, compression of the median nerve first disrupts the cutaneous fibers that supply the palmar surfaces of the thumb, index, middle, and the radial half of the ring finger. These digits form the median nerve’s primary palmar distribution, so numbness or tingling appears there earliest. The dorsal hand is mainly innervated by the radial nerve, so its sensation tends to be preserved early on. The little finger’s palmar surface is largely ulnar nerve territory, and the dorsal surface of the index finger is not primarily median-nerve–driven, so those areas aren’t typically the first affected.