Carpal Tunnel Syndrome
The flexor retinaculum is a strong fibrous band of tissue which crosses the carpal bones in the front of the hand (transverse carpal ligament). The flexor retinaculum is attached medially to the pisiform and the hook of hamate. Laterally, it is attached to the tubercle of the scaphoid and the crest of the trapezium.
The flexor retinaculum covers the median nerve and the flexor tendons. The structures that descend from the forearm to the hand either pass on the surface of the flexor retinaculum or inside the carpal tunnel. The ulnar nerve lies medial to the flexor retinaculum. The median nerve enters the hand through the carpal tunnel, deep to the flexor retinaculum. Other structures that pass through the carpal tunnel include all flexor tendons of the fingers and thumb.
Inflammation of the carpal tunnel compresses the median nerve and causes tingling, numbness, weakness or pain in the thumb, index finger, middle finger and half of the ring finger. Surgical release of the carpal tunnel is needed and the flexor retinaculum is cut to relieve the pressure being placed on the median nerve.