Contents

Name of bone

Lunate

Location/Articulation

The lunate bone (semilunar bone) is a carpal bone (wrist bone) in the human hand that may be distinguished by its deep concavity and crescentic outline. It is situated in the center of the proximal row of the carpus (wrist) region between the forearm and hand (manus). In standard medical posture, the lunate carpal bone is situated between the lateral scaphoid bone and medial triquetral bone. The lunate carpal bone straddles  distally the bordering ulna and radius bones and proximally to the distal carpus (wrist) trapezium and trapezoid bones.

The etymology of the lunate bone derives from the Latin luna which means “moon,” as the lunate bone looks similar to a crescent moon.


Figure 1. Bones of the left hand, dorsal surface

Muscle and ligament attachments

Surface anatomy

  • The superior surface, convex and smooth, articulates with the radius.
  • The inferior surface is deeply concave, and of greater extent from before backward than transversely: it articulates with the head of the capitate, and, by a long, narrow facet (separated by a ridge from the general surface), with the hamate.
  • The dorsal and palmar surfaces are rough, for the attachment of ligaments, the former being the broader, and of a somewhat rounded form.
  • The lateral surface presents a narrow, flattened, semilunar facet for articulation with the scaphoid.
  • The medial surface is marked by a smooth, quadrilateral facet, for articulation with the triangular bone.


Figure 2. Surface anatomy of the lunate bone

Radiography

Physical examination

Embryology

Anomalies

Injuries/Disorders

The lunate bone is the most frequently dislocated carpal bone. 

It is also subject to Keinbock’s disease, an osteomalacia of the lunate. Kienbock’s disease is another name for avascular necrosis (death and fracture of bone tissue due to interruption of blood supply) with fragmentation and collapse of the lunate. This has classically been attributed to arterial disruption, but may also occur after events that produce venous congestion with elevated interosseous pressure.

Attachments:


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