|Primary Type||Synovial Joint|
|Secondary Type||Condyloid Joint|
|Bones||Metacarpal, Proximal Phalanx (Hand)|
|Ligaments||Capsule, two collateral ligaments, palmar (volar) ligament|
|Innervation||Digital nerves from the ulnar and median nerves|
|Vasculature||Deep digital arteries from the superficial palmar arch|
|Conditions||Hitchhiker Thumb Deformity|
The metacarpophalangeal joints (MCP) are condyloid joints situated between the metacarpal bones and the proximal phalanges of the fingers. The are formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the proximal phalanges. The condyloid formation allows the movements of flexion, extension, abduction, adduction and circumduction.
Arthritis of the MCP is a distinguishing feature of Rheumatoid Arthritis, as opposed to the distal interphalangeal joint in Osteoarthritis.
Two collateral ligaments These strengthen the capsule on each side and pass from the head of the metacarpal to the base of the phalanx.
Palmar ligament (volar ligament) A fibrocartilaginous plate that connects the collateral ligaments and attaches firmly to the base of the proximal phalanx and loosely to the head of the metacarpal