The lunate (os lunatum or semilunar) is one of the carpal bones and is a component of the proximal carpal row.
On this page:
Gross anatomy
Osteology
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.
Articulations
along with the scaphoid and triquetrum forms the distal articular surface of the radiocarpal joint
-
intercarpal articulations
scaphoid (lateral)
capitate (distal)
triquetrum (medial)
hamate (distal and medial) - only in type II lunate
articulates with the triangular fibrocartilage complex
Attachments
Musculotendinous
none
Ligamentous
-
intrinsic ligaments
-
extrinsic ligaments
palmar: radiolunotriquetral, radioscapholunate, ulnolunate ligaments
Arterial supply
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
Variant anatomy
variation in articular facets (see: lunate morphology)
-
associated accessory ossicles
os hypotriquetrum
bipartite lunatum 6
Radiographic appearance
Plain radiograph
-
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
Development
Ossification
Ossification typically begins at age four and is complete by age six or seven 2.
History and etymology
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".
Related pathology
scapholunate advanced collapse (SLAC wrist)
Unable to process the form. Check for errors and try again.