The triquetral bone (or triquetrum) is a somewhat pyramidal-shaped carpal bone with a base and distally and medially pointed apex. It articulates with three bones.

The base of the triquetral connects with the lunate bone. The lateral aspect of the bone articulates with the hamate bone, while the medial aspect is non-articular. And finally, the palmar surface connects with the pisiform bone.

Due to its appearance, the triquetral is sometimes also called the carpal cuneiform. The name of this bone is derived from Latin and means three-cornered.

The triquetral is easily distinguished by its single, circular, and isolated articular surface for the pisiform found on its palmar aspect. Overall, the triquetral has the following three articular surfaces:

Articular surface for lunate - almost square-shaped; directed proximally and laterally;
Articular surface for hamate - appears concave-convex; directed laterally and distally; broader proximally and narrower distally;
Articular surface for pisiform - single, oval-shaped.

The largest articular surface is for the hamate. The articular surfaces for the lunate and hamate are continuous with each other.

Note: 3D model displays the left triquetral.

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Triquetral