Bone · Hand

Triquetral

Os triquetrum

A pyramid-shaped bone at the little-finger end of the proximal row. It does not touch the ulna: a disc of fibrocartilage is interposed between the two, so the ulna reaches the wrist only through soft tissue while the radius meets the carpus bone on bone. On its palm-side surface is a single oval facet, and that facet carries the pisiform. Its most consequential joint faces the other way — a spiral, helically curved surface shared with the hamate.