The metacarpophalangeal joints (MCP) refer to the joints between the metacarpal bones and the phalanges of the fingers. That means the MCP joint is the knuckle between the hand and the finger. These 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 first phalanges, with the exception of that of the thumb, which is a ginglymus.