The triquetral (triquetrum, cuneiform of the hand, pyramidal bone, cubital bone, triangular bone) is one of the eight carpal bones found in the hand. It is situated at the medial end of the proximal row, medial to the lunate and proximal to the hamate. The pisiform is located anteriorly, whilst the triquetral articulates with the triangular articular cartilage and ulnar styloid at the wrist. It is not palpable.
Anterior view in anatomical position of left triquetral
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The triquetral is pyramidal in shape, hence its name. There is an oval articular facet on the distal palmar surface for articulation with the pisiform. The medial and distal surfaces run together, limited only by a ridge distally. The hamate surface has a complex shape which is broader proximally. The square lunate surface is placed laterally.
- The ulnar collateral ligament attaches to the distal part of the distal surface.
- Articulates with the triangular articular cartilage and the ulnar styloid at the wrist
- Articulates with the lunate at the intercarpal joint
- Articulates with the pisiform at the pisotriquetral joint
- Articulates with the hamate at the midcarpal joint.
The triquetral begins to ossify in the third year.
- May fracture.