Which nerve is involved in carpal tunnel syndrome?

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

Answer: (D)

Carpal tunnel syndrome occurs when the median nerve is compressed as it passes through the carpal tunnel in the wrist. This tunnel is formed by the carpal bones on one side and the flexor retinaculum on the other, and it also contains several flexor tendons. When the median nerve is compressed here, it produces numbness, tingling, and sometimes weakness in the thumb, index finger, middle finger, and the radial half of the ring finger, reflecting its sensory and motor branches to the hand. The weakness often affects the thenar muscles, leading to problems with thumb opposition.

The ulnar nerve would produce symptoms on the little finger side of the hand and affect other intrinsic hand muscles; the radial nerve affects the back of the hand and wrist extension; and the sciatic nerve is a nerve of the leg, not the wrist. Thus, the median nerve is the one involved in carpal tunnel syndrome.