Carpal tunnel syndrome, also known as median nerve compression, is a condition affecting the hand, which causes tingling, numbness or weakness in the hand or wrist. The median nerve is located on the palm side of your hand which is also known as the carpal tunnel. The median nerve is responsible for providing sensation to the thumb, the index finger, and parts of the ring finger. The nerve is responsible for the muscle going to the thumb. Carpal tunnel syndrome can occur in any or both of your hands.