Ligament · Hand

Palmar carpal ligament

Ligamentum carpi palmare

A transverse thickening of the deep fascia of the forearm, lying across the front of the wrist just above and superficial to the flexor retinaculum — and routinely confused with it. The flexor retinaculum beneath is the roof of the carpal tunnel; this thinner, more superficial band roofs a second and much smaller passage on the little-finger side, Guyon's canal, through which the ulnar nerve and artery reach the hand. On the ulnar side it attaches around the pisiform and the tendon of flexor carpi ulnaris; on the radial side it fades into the fascia over the front of the distal radius. Telling the two apart is the whole value of knowing it exists: the median nerve passes beneath the retinaculum, while the ulnar nerve passes over the retinaculum and beneath this ligament.