Upper limb
Triquetral bone
Os triquetrum
- Origin
- Ulnar bone of the proximal row, triangular in shape. It meets the lunate radially, the hamate distally and the pisiform on the palmar side; proximally the TFCC disc lies between it and the ulna rather than the ulna itself.
- Insertion
- Attachment for the lunotriquetral ligament, the ulnocarpal ligaments and the triquetrohamate ligament.
- Function
- Carries the ulnar pillar of the wrist and limits ulnar deviation through its oblique contact with the hamate.
- Innervation
- Posterior interosseous nerve and dorsal branch of the ulnar nerve (articular branches, C7-C8)
- Movement & chain
- In ulnar deviation it slides distally along the hamate and emerges from under the ulnar styloid process.
- Palpation
- From the back, just distal to the ulnar styloid process, clearest with the wrist in radial deviation.
- Clinical
- After the scaphoid the most commonly fractured carpal, usually as a dorsal chip after a fall in dorsiflexion. Lunotriquetral ligament injury produces a clicking, painful ulnar wrist.
- Segmental innervation
- C7-C8
- In clinical practice
- In ulnar wrist pain, separate this bone from the TFCC and the distal radio-ulnar joint: all three hurt on ulnar deviation and loading.
- Region in the model
- Upper limb