Trapezoid Bone

Description

Normal anatomy of the carpal bones. Diagram of the wrist (frontal view) shows the eight carpal bones and the three carpal arcs (Gilula arcs), which are shown as pink (arc I), blue (arc II), and red (arc III) lines. C (capitate), H (hamate), L (lunate), P (pisiform), S (scaphoid), Tm (trapezium), Td (trapezoid), Tr (triquetrum)

Wrist radiograph with carpal bones labeled

Alternative Names

• Carpal Trapezoid
• Os trapezoideum
• Lesser Multangular Bone
• Intermediate Multangular Bone
• Trapezoid

General

• The smallest carpal bone in the distal row
• Located lateral to the Capitate
• Trapezium and Trapezoid are collectively known as the multangulars

Anatomic Description

• Dorsal surface is larger than the palmar surface
• The distal surface is triangular, with a palmar apex
• The medial and lateral surfaces are both narrow
• The medial surface is concave while the lateral surface is convex

Articulations

• Scaphoid articulates with the proximal surface
• Base of the second metacarpal articulates with the distal surface
• Trapezium articulates with the lateral surface
• Capitate articulates with the medial surface

Ligament Attachments

• Trapezio-trapezoid
• Trapezio-capitate
• Dorsal intercarpal
• Scapho-trapezium-trapezoid

Vascular Supply

• The dorsal intercarpal and basal metacarpal arches

Innervation

• Anterior interosseous branch of the median nerve
• Posterior interosseous branch of the radial nerve
• Dorsal and the deep branches of the ulnar nerve

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Clinical Significance

• Trapezoid Fracture
• Carpal Instability
• CMC arthritis

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See Also

• Hand and Wrist Anatomy (Main)
• Hand And Wrist Anatomy
• Wrist Pain (Main)

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