The carpal tunnel is a narrow space in the wrist. It contains wrist bones and a ligament (transverse carpal ligament) across the wrist where the palm and forearm meet. Tendons and the median nerve pass through this space to your hand. The median nerve supplies feeling and some movement to part of the hand.

Carpal tunnel syndrome is usually caused when an illness or other problem makes the carpal tunnel space too small. This puts pressure on the median nerve and causes pain, tingling, and other symptoms.