Lunate

Last revised by Dr Daniel J Bell on 24 Sep 2021

The lunate (os lunatum or semilunar) is one of the carpal bones and is a component of the proximal carpal row.

The lunate is crescent-shaped with a proximal convex articular facet and a distal concave articular facet. On the medial surface is a square-shaped facet and on the lateral surface is a semilunar facet. It is broader anteriorly than it is posteriorly. 

  • nil
  • branches from the dorsal radiocarpal arch and dorsal intercarpal arch supply the lunate via the dorsal and palmar surfaces (80%) or palmar surface only (20%) 2
  • frontal projection (neutral wrist position)
    • more than one-half should contact distal radial articular surface 3
    • should have a 'square shape' and the intercarpal joints should be uniformly 1-2 mm wide
    • forms part of the carpal arcs

Ossification typically begins at age four and is complete by age six or seven 2

From the Latin "luna" meaning moon, referring to the crescent-moon shape of the lunate. It was first named the "lunatum" in 1653 by Lyser, and has also been termed the "lunare" or "semilunare".

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Cases and figures

  • Figure 1: expected position os epilunate
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  • Figure 2: carpal bones
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  • Figure3: lunate (Gray's illustration)
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