Surface markings are, proximally, the distal wrist crease; distally, the hook of the hamate bone.
The recurrent thenar branch of the median nerve, the motor branch to the thenar emminence, leaves the median nerve in or beyond the carpal tunnel, then curves back over the flexor retinaculum to reach the thenar emminence. It is endagered in carpal tunnel surgery if the incision over the carpal tunnel is mede too far laterally (thumb side).
The base and walls of the carpal tunnel are a concave bony channel formed by the carpal bones.
The flexor retinaculum, or transverse carpal ligament, forms the roof of the carpal tunnel. It attaches to the scaphoid tubercle and ridge of the trapezium laterally, and to the pisiform and hook of the hamate laterally.
From superficial to deep, the structures encountered in exposing the carpal tunnel, are:
The carpal tunnel transmits: