Midcarpal Joint

Description

The midcarpal joint

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

Name

• Midcarpal Joint

General

• Functional compound synovial joint of the wrist
• Located between the proximal carpal row and distal carpal row
• Permits flexion/extension, adduction/adduction of the wrist

Gross Anatomy

• Proximally bounded by the Joints of the Proximal Carpal Row
  • From lateral to medial: scaphoid, lunate, triquetrum, pisiform
• Distally bounded by the Joints of the Distal Carpal Row
  • From lateral to medial: trapezium, trapezoid, capitate, hamate
• Two saddle joints:
  • First between the capitate, hamate and scaphoid, lunate, triquetrum
  • Second between the trapezium, trapezoid and scaphoid
• The carpometacarpal joints of digits 2-5 communicate with the midcarpal bones in a single synovial cavity

Joint Capsule

• Forms a series of synovial gliding joints between the proximal and distal rows
• Lined with hyaline cartilage, encompassed in fibrous capsule lined with synovial membrane
• Large, and irregular it separates the two rows
• Does not blend with the wrist joint cavity due to interosseous intercarpal ligaments

Movement

• Consists of two saddle joints which allow movement in two planes
• Flexion/extension and abduction/adduction of the wrist
• Primary joint involved in radial/ulnar deviation

Ligaments

• Interosseous Intercarpal Ligaments
• Palmer Midcarpal Ligaments (Palmer Intercarpal Ligaments)
• Dorsal Midcarpal Ligaments (Dorsal Intercarpal Ligaments)
• Radial Collateral Ligament of the Wrist
• Ulnar Collateral Ligament of the Wrist

Vascular Supply

• Posterior carpal branches of the radial artery
• Posterior carpal branches of the ulnar artery
• Anterior interosseous artery (branch of the ulnar artery)

Innervation

• Deep terminal branch of the ulnar nerve
• Anterior interosseous branch of the median nerve
• Posterior interosseous branch of the radial nerve

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Clinical Significance

• Carpal Instability

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See Also

• Wrist Anatomy Main
• Physical Exam Wrist
• Hand Pain Main

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