Triquetrum !
The triquetrum is a wrist bone on the little-finger side of the first row; after the scaphoid it is the carpal bone most often fractured.
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What it is
A pyramid-shaped wrist bone on the little-finger side.
What it does
One of the eight carpal bones that let the wrist bend and carry load to the forearm.
Key facts
- Joints with
- Lunate, pisiform, hamate; TFCC
- Landmarks
- Pyramid shape; facet for the pisiform
Relations
- Lateral
- Lunate, joined by the lunotriquetral ligament
- Above
- TFCC and the ulnocarpal ligaments, which separate it from the ulnar head
- Below
- Hamate, at a spiral-shaped joint
- In front
- Pisiform on its palmar facet; the ulnar nerve and ulnar artery pass close by in Guyon's canal
- Behind
- Dorsal ridge with the dorsal radiocarpal ligament and dorsal intercarpal ligament
- Medial
- Ulnar collateral ligament of the wrist; the ECU tendon passes near it
How to find it
With the wrist in radial deviation it is felt on the back of the little-finger side, just distal to the ulnar styloid process; the pisiform sits on its palmar surface.
Examination
- Lunotriquetral ballottement (shuck) test: the lunate and triquetrum are shifted against each other; pain or excess movement suggests a lunotriquetral ligament injury
On imaging
Dorsal chip fractures often show only on the lateral or an oblique view, as a small flake behind the proximal row; CT if X-rays are unclear. Body fractures are usually part of a perilunate (greater arc) injury.
Clinical notes
- Its upper surface meets the triangular fibrocartilage, not the ulna, so TFCC tears and ulnocarpal impaction load it and cause pain on the little-finger side of the wrist
- A dorsal chip fracture is usually treated in a splint and heals well, but tenderness here also raises the question of a lunotriquetral ligament injury
Anatomical variants
- Lunotriquetral coalition (fusion with the lunate), the most frequent carpal coalition, usually painless and seen by chance on X-ray
Development
Ossifies around age 2–3, the third carpal bone to appear.
Test yourself
Think of the answer, then tap the question to see it.
What is the most common fracture of the triquetrum?
A small dorsal chip fracture after a fall or forced flexion; it is usually the second most fractured carpal bone.
Why do chip avulsions of the triquetrum occur on its dorsal ridge?
The dorsal radiocarpal and dorsal intercarpal ligaments both attach there.
Which test assesses the ligament between the lunate and the triquetrum?
The lunotriquetral ballottement (shuck) test: pain or excess movement suggests a lunotriquetral ligament injury.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- os triquetrum TA2 1253
- Official Spanish (DeCS)
- Hueso piramidal
- English (TA2)
- Triquetrum
- Also called
- triquetral bone
Related
- Dorsal intercarpal ligament
- Dorsal radiocarpal ligament
- ECU
- FCU tendon
- Flexor retinaculum
- Lunotriquetral ligament
- Midcarpal ligaments
- Pisiform ligaments
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Hand Carpal Bones; 8.2 Bones of the Upper Limb (OpenStax (Rice University), 2022) · adapted, CC BY 4.0.
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Representative model, for educational purposes only.
