metacarpofalangeale

The metacarpofalangeale gewrichten, in English metacarpophalangeal joints (MCP joints), are the joints between the heads of the metacarpal bones in the hand and the bases of the proximal phalanges of the fingers. They are synovial, diarthrodial joints that enable movement of the fingers and contribute to hand grip and precision manipulation.

Anatomy and biomechanics: The MCP joints are reinforced by a joint capsule, the radial and ulnar collateral ligaments, and a thickened palmar plate (volar plate) on the palmar aspect. The articular surfaces consist of convex metacarpal heads articulating with the concave bases of the proximal phalanges. In digits II–V, these joints are typically classified as ellipsoid (condyloid) joints and allow two main degrees of freedom: flexion-extension and abduction-adduction, with limited circumduction. The thumb’s MCP joint is functionally more hinge-like but participates in grasp with the thumb’s carpometacarpal joint.

Function and muscles: The MCP joints coordinate with the extensor mechanism and intrinsic hand muscles (interossei and lumbricals) to flex the metacarpophalangeal joints while extending the interphalangeal joints, enabling gripping, pinching, and precise finger movements. The volar plate and collateral ligaments help guide motion and protect against hyperextension and lateral stress.

Clinical relevance: MCP joints are commonly involved in rheumatic diseases, such as rheumatoid arthritis, which can cause synovitis and deformities. They are also sites of injury, including collateral ligament tears (notably the ulnar collateral ligament of the thumb MCP) and dislocations. Understanding their anatomy is important for diagnosing pain, stiffness, and deformity in the hand.