Triquetrum Bone

The triquetrum is a pyramidal-shaped, three-faced, formerly cuneiform types bone and one of eight carpal bones that forms part of the medial side of the proximal row of the carpus between the lunate and pisiform bones. It is the 2nd commonly fractured carpal bone and the name triquetrum has come from the Latin word triquetrous which means “three-cornered” sometimes it is also called triquetral bone, triangular bone, or cuneiform bone.  It is on the ulnar side of the hand and makes a connection with the pisiform, hamate, and lunate bones that do not articulate with the ulna.

Structure

It is a three-faced bone seen within the proximal row of carpal bones situated beneath the pisiform, forming the carpal arch, within which lies in the carpal tunnel and under the pisiform.

To facilitate its palpation in an exam, the hand help to deviate radially on the palmar perspective so that the triquetrum moves out from under the ulnar styloid process. Its apex points disto-medially towards the pisiform bone, which is situated upon its palmar facet. It sits upon the hamate bone, which is in the distal row of carpal bones, and its base faces laterally articulating with the lunate bone.

Surfaces

The superior surface is situated on a medial side, rough, non-articular portion,

The lateral surface is convex in shape and articulates with the triangular articular disk of the wrist joint.

The inferior surface is concavely directed lateralward, sinuously smooth curved shape, for articulation with the hamate.

The dorsal surface is rough for the articulation of ligaments.

The volar surface oval shape facet is situated on its medial part, for articulation with the pisiform with rough ligamentous attachment.

The lateral surface, by a flat, quadrilateral facet on the base of the pyramid shape, for articulation with the lunate.

The medial surface roughened the summit of the pyramid, for the attachment of the ulnar collateral ligament of the wrist.

 

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