The intercarpal articulation is the joint between the two rows of carpal bones and is formed by the distal articular facets of the navicular, lunate, and triquetral bones on one side, and by the proximal facets of the trapezium, trapezoid, capitate, and hamate bones on the other side. The first row of the carpal bones practically forms a socket for the head of the capitate and the proximal portion of the hamate. The proximal row exhibits a convex and the distal row a concave surface. The line of the joint is not a simple curve, but has an irregular U-shape. The articular cavity of the joint is very complicated, since it extends from the actual articular line both proximally and distally between the individual carpal bones of both rows. It is separated from the radiocarpal joint by the ligaments between the proximal carpal bones, and similar ligaments connect the bones of the second row and separate the intercarpal from the carpo-metacarpal articulation. The latter separation is incomplete, however, and these two articulations usually communicate between the capitate and the trapezoid bone. The thin articular capsule is similar to that of the radiocarpal articulation.