Lunate

Last revised by Craig Hacking on 12 Dec 2023

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. 

  • none

  • 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

  • lateral projection

    • has a cup-shaped appearance, with the base of the capitate sitting in the cup

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: carpal bones
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  • Figure 2: lunate (Gray's illustration)
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  • Case 1: labeled 2
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  • Case 2: labeled 7
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  • Case 3: lunate replacement
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