Triquetral bone

Triquetral bone
File:Triangular bone (left hand) 01 palmar view.png Left hand anterior view (palmar view). Triquetral bone shown in red.
The left triquetal bone
Details
Latin	os triquetrum, os pyramidale, os triangulare
Articulations	articulates with three bones: lunate laterally pisiform in front hamate distally triangular articular disk which separates it from the lower end of the ulna.
Identifiers
MeSH	A02.835.232.087.319.150.831
Dorlands /Elsevier	o_07/12598819
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	23715
Anatomical terms of bone [[[d:|edit on Wikidata]]]

The triquetral bone (/traɪˈkwɛtrəl/ or /traɪˈkwiːtrəl/; also called triquetrum, pyramidal, three-cornered or triangular bone, and formerly cuneiform bone) is located in the wrist on the medial side of the proximal row of the carpus between the lunate and pisiform bones. It is on the ulnar side of the hand, but does not articulate with the ulna. It connects with the pisiform, hamate, and lunate bones. It is the 3rd most commonly fractured carpal bone.

Structure

The triquetral is one of the eight carpal bones of the hand. It is a three-sided bone found within the proximal row of carpal bones. Situated beneath the pisiform, it is one of the carpal bones that form the carpal arch, within which lies the carpal tunnel.

The triangular bone may be distinguished by its pyramidal shape, and by an oval isolated facet for articulation with the pisiform bone. It is situated at the upper and ulnar side of the carpus. To facilitate its palpation in an exam, the hand must be radially deviated so that the triquetrium moves out from under the ulnar styloid process. The triquetrum may be difficult to find, since it also lies under the pisiform.

Ossification

The triquetral bone ossifies between 9 months and 50 months (4 years and 2 months).

Surfaces

The superior surface presents a medial, rough, non-articular portion, and a lateral convex articular portion which articulates with the triangular articular disk of the wrist.

The inferior surface, directed lateralward, is concave, sinuously curved, and smooth for articulation with the hamate. The dorsal surface is rough for the attachment of ligaments.

The volar surface presents, on its medial part, an oval facet, for articulation with the pisiform; its lateral part is rough for ligamentous attachment.

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

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

In animals

In reptiles and amphibians, the bone is instead referred to as the ulnare, since (at least in the most primitive fossils) it articulates with the ulna.

Function

The carpal bones function as a unit to provide a bony superstructure for the hand.

History

The etymology derives from the Latin triquetrus which means "three-cornered."

Additional images

• Triangular bone (left hand) - animation01.gif

  Triquetral bone of the left hand (shown in red). Animation.

• Triangular bone (left hand) - animation02.gif

  Triquetral bone of the left hand. Close up. Animation.

• Triquetral bone.jpg

  Triquetral bone.

• RightHumanPosteriorDistalRadiusUlnaCarpals - Triquetral bone.png

  Right hand posterior view (dorsal view). Thumb on bottom.

• RightHumanAnteriorDistalRadiusUlnaCarpals - Triquetral bone.png

  Right hand anterior view (palmar view). Thumb on top.

• Gray219 - Triangular bone.png

  Bones of the left hand. Palmar surface. Triquetral shown in yellow.

• Gray220- Triangular bone.png

  Bones of the left hand. Dorsal surface. Triquetral shown in yellow.

• Ospoignet - Triquetral bone.png

  Cross section of wrist (thumb on left). Triquetral shown in red.

• Dorsale Triquetrumabsprengung - CT VRT with arrow.png

  Triquetral fracture indicated by the white arrow.

• TriQFracture.PNG

  Triquetral fracture as seen on X ray.

See also

This article uses anatomical terminology; for an overview, see Anatomical terminology.

• Pisiform bone