<P> The midcarpal joint is formed by the scaphoid, lunate, and triquetral bones in the proximal row, and the trapezium, trapezoid, capitate, and hamate bones in the distal row . The distal pole of the scaphoid articulates with two trapezial bones as a gliding type of joint . The proximal end of the scaphoid combines with the lunate and triquetrum to form a deep concavity that articulates with the convexity of the combined capitate and hamate in a form of diarthrodial, almost condyloid joint . </P> <P> The cavity of the midcarpal joint is very extensive and irregular . The major portion of the cavity is located between the distal surfaces of the scaphoid, lunate, and triquetrum and proximal surfaces of the four bones of the distal row . Proximal prolongations of the cavity occur between the scaphoid and lunate and between the lunate and triquetrum . These extensions reach almost to the proximal surface of the bones in the proximal row and are separated from the cavity of the radiocarpal joint by the thin interosseous ligaments . There are three distal prolongations of the midcarpal joint cavity between the four bones of the distal row . The joint space between trapezium and trapezoid, or that between trapezoid and capitate, may communicate with cavities of the carpometacarpal joints, most commonly the second and third . The cavity between the first metacarpal and carpus is always separate from the midcarpal joint; the joint cavity between the hamate and fourth and fifth metacarpals is a separate cavity more often than not, but it may communicate normally with the midcarpal joint . </P> <P> The wrist is perhaps the most complicated joint in the body . It permits movements in three planes - extension / flexion, ulnar deviation / radial deviation, and pronation / supination - and allows complex patterns of motion under significant strain . </P> <P> Optimal wrist function requires stability of the carpal components in all joint positions under static and dynamic conditions . </P>

The midcarpal joint separates the proximal and distal rows of carpal bones