Upper limb
Lunate bone
Os lunatum
- Origin
- Middle bone of the proximal row, crescent shaped in side view. Its convex top sits in the lunate fossa of the radius and its concave underside cups the head of the capitate.
- Insertion
- Attachment for the scapholunate ligament, the lunotriquetral ligament and the palmar radiocarpal ligaments.
- Function
- Carries the main load transfer from the hand to the radius and forms the hinge between the radial and ulnar pillars.
- Innervation
- Anterior and posterior interosseous nerves (articular branches, C6-C8)
- Movement & chain
- It tilts backwards in palmar flexion and rises as a bulge under the finger; in dorsiflexion it sinks away again.
- Palpation
- From the back, distal to Lister tubercle, clearest with the wrist in palmar flexion.
- Clinical
- Kienbock disease: avascular necrosis of the bone, with gradual wrist pain and loss of force in young adults. In high energy trauma, perilunate dislocation or palmar dislocation of the bone itself, threatening the median nerve.
- Segmental innervation
- C6-C8
- In clinical practice
- Persistent diffuse wrist pain without clear trauma in a young adult is reason to consider Kienbock disease and request imaging.
- Region in the model
- Upper limb