Trapezoid bone

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Trapezoid bone
Trapezoid bone (left hand) 01 palmar view.png
Left hand anterior view (palmar view). Trapezoid bone shown in red.
Gray226.png
The left trapezoid bone.
Latin os trapezoideum, os multangulum minus
Gray's p.225
Articulations articulates with four bones:
scaphoid proximally
second metacarpal distally
trapezium bone laterally
capitate medially
MeSH Trapezoid+Bone
TA A02.4.08.010
FMA FMA:23724
Anatomical terms of bone

The trapezoid bone (lesser multangular bone) is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges. It is homologous with the "second distal carpal" of reptiles and amphibians.

Structure[edit]

The trapezoid is a four-sided carpal bone found within the hand. The trapezoid is found within the distal row of carpal bones.[1] :708

Surfaces[edit]

The superior surface, quadrilateral, smooth, and slightly concave, articulates with the scaphoid.

The inferior surface articulates with the proximal end of the second metacarpal bone; it is convex from side to side, concave from before backward and subdivided by an elevated ridge into two unequal facets.

The dorsal and palmar surfaces are rough for the attachment of ligaments, the former being the larger of the two.

The lateral surface, convex and smooth, articulates with the trapezium.

The medial surface is concave and smooth in front, for articulation with the capitate; rough behind, for the attachment of an interosseous ligament.

Function[edit]

The carpal bones function as a unit to provide a bony superstructure for the hand.[1] :708

History[edit]

The etymology derives from the Greek trapezion which means "irregular quadrilateral," from tra- "four" and peza "foot" or "edge." Literally, "a little table" from trapeza meaning "table" and -oeides "shaped."

Additional images[edit]

See also[edit]

This article uses anatomical terminology; for an overview, see anatomical terminology.

References[edit]

This article incorporates text from a public domain edition of Gray's Anatomy.

  1. ^ a b Drake, Richard L.; Vogl, Wayne; Tibbitts, Adam W.M. Mitchell; illustrations by Richard; Richardson, Paul (2005). Gray's anatomy for students. Philadelphia: Elsevier/Churchill Livingstone. ISBN 978-0-8089-2306-0.