Triquetral bone

The triquetral bone (

The triquetral 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.

The triquetral bone has nutrient foramina for entering the nutrient vessels into the bone which comes from branches of the radial, ulnar, and interosseous arteries.^[4]

Ossification

The triquetral bone ossifies between 9 months and 50 months (4 years and 2 months).^[5]

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.^{[3] : 708}

Fracture

Triquetral fractures can occur due to forceful flexion of the wrist, causing an

Etymology

The etymology derives from the Latin triquetrus which means "three-cornered." Therefore, it is sometimes also called the triangular bone or os triangulare. However, os triangulare may also refer to a nearby accessory bone.

Additional images

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  Triquetral bone of the left hand (shown in red). Animation.
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  Triquetral bone of the left hand. Close up. Animation.
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  Triquetral bone.
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  Right hand posterior view (dorsal view). Thumb on bottom.
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  Right hand anterior view (palmar view). Thumb on top.
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  Bones of the left hand. Palmar surface. Triquetral shown in yellow.
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  Bones of the left hand. Dorsal surface. Triquetral shown in yellow.
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  Cross section of wrist (thumb on left). Triquetral shown in red.
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  Triquetral fracture indicated by the white arrow.
• 
  Triquetral fracture as seen on lateral view of a radiograph.

References

See also

Wikimedia Commons has media related to Triquetral bone.

This article uses anatomical terminology.

• Pisiform bone