JointUpper limb

Metacarpophalangeal joints

articulationes metacarpophalangeae

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Study entry

Classification

Ellipsoid synovial joints.

Surfaces

Heads of the metacarpals with the bases of the proximal phalanges.

Capsule

Each with its own capsule, reinforced by two collateral ligaments (a cord-like part, from the head of the metacarpal to the base of the phalanx, and a fan-shaped part, to the palmar ligament) and by the palmar ligament (fibrocartilaginous plate on the anterior surface). The palmar ligaments of the 2nd to the 5th are joined by the deep transverse metacarpal ligaments.

Movements

In the 2nd to 5th fingers: flexion-extension, abduction-adduction and circumduction. In the thumb, only flexion-extension. The collaterals become taut in flexion, which is why the fingers cannot be abducted with the metacarpophalangeal joint fully flexed.

Blood supply

Deep digital arteries, branches of the superficial palmar arch.

Innervation

Digital nerves from the ulnar and median nerves.

Source: cap. 3, «Articulaciones del miembro superior: articulaciones metacarpofalángicas e interfalángicas»

Clinical correlation

Dupuytren contracture

Disease of the palmar fascia: the palmar aponeurosis gradually shortens, thickens and becomes fibrotic. The longitudinal bands on the medial side of the hand pull the 4th and 5th fingers, which stay half flexed at the metacarpophalangeal and proximal interphalangeal joints. It is usually bilateral, in men after 50, with probable inheritance. It begins with nodules attached to the skin of the palm and then raised cords form as far as the base of the 4th and 5th fingers. Treatment is to surgically remove the fibrosed fascia.

Skier's thumb and gamekeeper's thumb

Skier's thumb: rupture or chronic laxity of the collateral ligament of the 1st metacarpophalangeal joint, from hyperabduction when the ski pole holds the thumb while the hand hits the ground or sinks into the snow; in severe cases, the head of the metacarpal suffers an avulsion fracture. Gamekeeper's thumb (of someone riding a mechanical bull): sprain of the radial collateral ligament with avulsion of the lateral part of the proximal phalanx of the thumb.

Related clinical cases

Dupuytren contracture
Skier's thumb and gamekeeper's thumb