Carpal tunnel syndrome is due to inflammation of which nerve?

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

Answer: (B)

Carpal tunnel syndrome happens when the median nerve is compressed as it travels through the carpal tunnel in the wrist. The tunnel is bounded by wrist bones and the flexor retinaculum and contains the median nerve plus several flexor tendons; inflammation or swelling of these tendons can narrow the space and squeeze the nerve. This leads to numbness, tingling, and sometimes weakness in the areas served by the median nerve—typically the thumb, index, middle, and the radial side of the ring finger, and can involve the thumb’s thenar muscles. The other nerves listed don’t pass through the carpal tunnel in the same way: the ulnar nerve travels toward the little finger side of the hand, the radial nerve supplies the back of the hand and parts of the dorsal wrist, and the musculocutaneous nerve mainly supplies the anterior arm. Because the symptoms and the anatomical route point to a problem with the median nerve, that is the nerve involved.