Anatomy of the flexor retinaculum of the wrist and the flexor carpi radialis tunnel.

The flexor retinaculum forms a retinacular bridge over the carpal tunnel extending from ulnar to radial direction. Its main function is to protect the contained without a significant mechanical action in supporting the transverse carpal arch. The osteofibrous tunnel of flexor carpi radialis is independent and presents four sections. The palmaris longus tendon presents a distal insertion forming the superficial layer of the aponeurosis palmaris. The flexor carpi ulnaris tendon has four distal insertions.