Trapezium bone

Recommended video: Bones of the wrist and hand [23:54]

Overview of the bones of the hand and wrist.

The trapezium bone is one of the eight carpal bones of the hand. It is a cube shaped bone located on the radial side of the hand, in the distal carpal row, at the base of the thumb. It articulates with the first metacarpal, second metacarpal, scaphoid and trapezoid bones. The articulation between the first metacarpal and the trapezium, the carpometacarpal joint of the thumb, is a sellar (saddle) shaped joint which provides the human hand with the wide mobility common described as having “opposable thumbs”.

The main feature of this carpal bone is a tubercle located on the bone’s anterior (palmar) aspect, termed the tubercle of trapezium bone. Adjacent to this tubercle is the groove of trapezium bone. The palmar surface of the trapezium bone provides attachment for the flexor retinaculum and proximal attachment for the three thenar muscles of the hand (opponens pollicis, abductor pollicis brevis, flexor pollicis brevis). The groove contains the tendon of flexor carpi radialis. The lateral surface of the trapezium bone is the site of attachment for the radial collateral ligament.