When people hear the phrase “carpal tunnel,” they often think of the pain, numbness, or tingling that occurs when a major nerve (the median nerve) of the hand is squeezed or compressed. However, the carpal tunnel is a narrow passageway in the wrist that protects this nerve and the flexor tendons that bend the fingers and thumb. Carpel tunnel syndrome occurs when the tissues of the carpel tunnel swell, putting pressure on the median nerve.