Lunate Bone

Key Features & Anatomical Relations

The lunate bone (semilunar bone) is one of the eight carpal bones of the hand. It’s semilunar-shaped and found in the proximal row of carpal bones. It’s classified as a short bone and includes the following bony features:

- surfaces: proximal, distal, palmar, and dorsal surfaces;

- landmarks: radial, scaphoid, capitate, hamate, and triquetrum articular facets.

More information regarding these bony features can be found in the Surfaces and Landmarks tabs for this bone.

The lunate bone is located:

- proximal to the capitate and hamate bones;

- distal to the radius;

- medial to the scaphoid bone;

- lateral to the triquetrum bone.

It articulates with the:

- radius at the radiolunate joint, contributing to the formation of the radiocarpal (wrist) joint;

- triquetrum bone at the lunotriquetral joint;

- hamate bone at the lunohamate joint;

- capitate bone at the lunocapitate joint;

- scaphoid bone at the scapholunate joint.

Ossification

Ossification of the lunate bone occurs at one ossification center, which appears within the fourth to fifth years (Standring, 2016). Complete ossification occurs during adolescence.

Variations

In some individuals:

- carpal fusion, or coalition, between the lunate and triquetrum bones may be present, forming the os lunatotriquetrum;

- several accessory bones may be associated with the lunate bone (Tubbs, Shoja and Loukas, 2016).

Surface Anatomy

With regard to surface anatomy, the dorsal surface of lunate bone can be palpated on the dorsal aspect of the wrist, proximal to the capitate bone, during flexion of the wrist joint.

List of Clinical Correlates

- Dislocation of lunate bone (most commonly dislocated carpal bone)

- Perilunate dislocation

- Kienböck’s disease

- Fracture of lunate bone

References

Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Tubbs, R. S., Shoja, M. M. and Loukas, M. (2016) Bergman's Comprehensive Encyclopedia of Human Anatomic Variation. Wiley.