Note that the midcarpal joint is not strictly a single joint anatomically; however, the various articulations between the two rows of carpal bones function as a single unit.
The medial compartment consists of the articulation between the distal surfaces of triquetral, lunate and scaphoid and the proximal surfaces of hamate and capitate. The distal surface is largely convex, the proximal surface concave, except for the most medial part in which the opposite is true, giving a sellar shape.
A fibrous capsule encloses the joints of the carpus, with a synovial membrane lining this capsule, attaches to the margins of the articular surface of each carpal bone.
See wrist (region)
There are two types of joint system within the midcarpus: the uniaxial joint of scaphoid and distal row, and the biaxial joint between lunate, triquetrum and distal row. The intercarpal joints of the proximal row accommodate these movements and allow the joint surfaces to stay congruent.
Four ligaments stabilise the midcarpal joint:
- A dorsal ligament
- A palmar ligament
- A radial ligament
- An ulnar ligament.