Intercarpal joints

The intercarpal joints are the articulations between the individual carpal bones of the wrist. The eight carpal bones are arranged in two transverse rows — a proximal row (scaphoid, lunate, triquetrum, pisiform) and a distal row (trapezium, trapezoid, capitate, hamate) — and the intercarpal joints comprise the synovial articulations that link these bones to one another. [1-3]

They are conventionally described in three groups:

1 - Joints of the proximal row (proximal intercarpal joints) — the articulations between scaphoid, lunate, and triquetrum (scapholunate and lunotriquetral joints), united by interosseous ligaments. The pisiform articulates separately with the palmar surface of the triquetrum.

• Scapholunate joint — between the scaphoid and lunate, united by the scapholunate interosseous ligament

• Lunotriquetral joint — between the lunate and triquetrum, united by the lunotriquetral interosseous ligament

• Pisotriquetral joint — between the pisiform and the palmar surface of the triquetrum (a separate synovial articulation)

Joints of the distal row (distal intercarpal joints) — the articulations among trapezium, trapezoid, capitate, and hamate, connected by dorsal, palmar, and interosseous intercarpal ligaments.

• Trapeziotrapezoid joint

• Trapezocapitate joint

• Capitohamate joint

Midcarpal joint — The midcarpal joint is a compound joint with an approximately S-shaped joint line separating the proximal and distal carpal rows.

Its individual bone-to-bone articulations are:

• Scaphoid–trapezium

• Scaphoid–trapezoid

• Scaphoid–capitate

• Lunate–capitate

• Lunate–hamate

• Triquetrum–hamate

Thus, the complete list of named bone-to-bone intercarpal articulations is:

• Scapholunate

• Lunotriquetral

• Pisotriquetral

• Trapeziotrapezoid

• Trapezoid-capitate

• Capitate-hamate

• Scaphoid-trapezium

• Scaphoid-trapezoid

• Scaphoid-capitate

• Lunate-capitate

• Lunate-hamate

• Triquetrum-hamate

An important distinction for anatomical nomenclature is that the last six are usually considered components of the midcarpal joint, rather than six completely independent joints. The scaphoid acts as an important bridge between the two carpal rows.