Flexor retinaculum (transverse carpal ligament): strong fibrous band bridging the carpal arch (anterior concavity of the carpus), converting it into the osseofibrous carpal tunnel for passage of the digital flexor tendons.
Rectangular band formed by thickening of the deep fascia in front of the carpal bones.
Attachments
Medially: attached to the pisiform and the hook of the hamate.
Laterally: attached to the tubercle of the scaphoid and the crest of the trapezium.
Gives an additional slip on each side.
Medial (superficial) slip, the volar carpal ligament, attaches to the pisiform; the ulnar nerve and vessels pass deep to it.
Lateral (deep) slip attaches to the medial lip of the groove of the trapezium, forming a separate osseofibrous tunnel for the tendon of flexor carpi radialis.