trapeziocapitate

Trapeziocapitate refers to a potential articulation between the trapezium and the capitate, two of the carpal bones in the wrist. In standard wrist anatomy the distal carpal row runs from radial to ulnar as trapezium, trapezoid, capitate, and hamate. The capitate usually articulates proximally with the scaphoid and lunate and distally with the bases of the second, third, and fourth metacarpals; the trapezium articulates proximally with the scaphoid and distally with the base of the first metacarpal. Because the trapezoid lies between the trapezium and capitate in the distal row, a direct trapeziocapitate joint is not always present.

When described, the trapeziocapitate is a small planar articulation or facet that occurs between the articular surfaces of trapezium and capitate. It is variable among individuals and may be absent in many; if present, it permits limited gliding between the bones and can contribute to the overall mobility of the wrist during flexion, extension, and radial/ulnar deviation.

Clinical relevance is limited but the variation may be noted in imaging and can be considered in cases of carpal instability or trauma. Developmentally, carpal bones arise from mesenchymal condensations that ossify to form the distal carpal row, of which trapezium, trapezoid, capitate, and hamate are components. See also carpal bones, intercarpal joints, and midcarpal joint.