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The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.. The CMC joint of the thumb or the first CMC joint, also known as the trapeziometacarpal (TMC) joint, differs significantly from the other four CMC joints and is therefore described separately.
Besides the metacarpophalangeal joints, the metacarpal bones articulate by carpometacarpal joints as follows: the first with the trapezium; the second with the trapezium, trapezoid, capitate and third metacarpal; the third with the capitate and second and fourth metacarpals; the fourth with the capitate, hamate, and third and fifth metacarpals;
The carpometacarpal joint connects the carpal bones to the metacarpus or metacarpal bones which are joined at the intermetacarpal articulations. In the fingers, finally, are the metacarpophalangeal joints (including the knuckles) between the metacarpal bones and the phalanges or finger bones which are interconnected by the interphalangeal joints
Joints of the hand, X-ray Interphalangeal ligaments and phalanges. Right hand. Deep dissection. Posterior (dorsal) view. The PIP joint exhibits great lateral stability. Its transverse diameter is greater than its antero-posterior diameter and its thick collateral ligaments are tight in all positions during flexion, contrary to those in the metacarpophalangeal joint.
The intermetacarpal joints are in the hand formed between the metacarpal bones. The bases of the second, third, fourth and fifth metacarpal bones articulate with one another by small surfaces covered with cartilage. The metacarpal bones are connected together by dorsal, palmar, and interosseous ligaments.
Joints of the hand, X-ray. The bones in each carpal row interlock with each other and each row can therefore be considered a single joint. In the proximal row a limited degree of mobility is possible, but the bones of the distal row are connected to each other and to the metacarpal bones by strong ligaments that make this row and the metacarpus a functional entity.
A real differentiation appeared an estimated 70 mya in early primates, while the shape of the human thumb CMC finally appears about 5 mya. The result of this evolutionary process is a human CMC joint positioned at 80° of pronation, 40 of abduction, and 50° of flexion in relation to an axis passing through the second and third CMC joints. [40]
The CMC joint of the thumb allows a wide range of motion while maintaining stability for grasp and pinch. [citation needed] With this in mind, failure to properly recognize and treat the Bennett fracture will not only result in an unstable, painful, arthritic CMC joint with diminished range of motion: it will also result in a hand with greatly ...