Name of bone
The trapezium bone (greater multangular bone) is a carpal bone in the wrist. It is distinguished by a deep groove on its palmar surface. The trapezium is situated at the radial side of the carpus, between the scaphoid and the first metacarpal bone. It articulates at the first metacarpal distally, the scaphoid proximally, the trapezoid medially, and the second metacarpal medially.
The etymology derives from the Greek trapezion, which means "irregular quadrilateral;" literally, "a little table," from trapeza meaning table. Also, from tra- "four" and peza "foot" or "edge."
Muscle and ligament attachments
The tubercle of trapezium is an anatomic tubercle; the abductor pollicis brevis muscle sometimes attaches here.
- The superior surface is directed upward and medialward. Medially, the surface is smooth, and it articulates with the scaphoid. Laterally, it is rough and continuous with the lateral surface.
- The inferior surface is oval, with a saddle-shaped surface for articulation with the base of the first metacarpal bone.
- The dorsal surface is rough.
- The palmar surface is narrow and rough. At its upper part is a deep groove, running from above obliquely downward and medialward; it transmits the tendon of the flexor carpi radialis, and is bounded laterally by an oblique ridge. This surface gives origin to the opponens pollicis and to the abductor and flexor pollicis brevis. It also allows for attachment to the transverse carpal ligament.
- The lateral surface is broad and rough for the attachment of ligaments.
- The medial surface presents two facets: the upper, large and concave, articulates with the trapezoid; the lower, small and oval, articulates with the base of the second metacarpal.
Figure 1. Surface anatomy of the left trapezium bone.