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The metacarpophalangeal joints (MCP) are situated between the metacarpal bones and the proximal phalanges of the fingers. [1] These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the proximal phalanges . [ 1 ]
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 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.
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 .
The TMC joint is a synovial joint between the trapezium bone of the wrist and the metacarpal bone at the base of the thumb. This joint is a so-called saddle joint (articulatio sellaris), unlike the CMC joints of the other four fingers which are ellipsoid joints. [17] This means that the surfaces of the TMC joint are both concave and convex.
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.
The first metacarpal bone is short and thick with a shaft thicker and broader than those of the other metacarpal bones. Its narrow shaft connects its widened base and rounded head; the former consisting of a thick cortical bone surrounding the open medullary canal; the latter two consisting of cancellous bone surrounded by a thin cortical shell.
It is broader, and extends farther upward, on the volar than on the dorsal aspect, and is longer in the antero-posterior than in the transverse diameter. On either side of the head is a tubercle for the attachment of the collateral ligament of the metacarpophalangeal joint.