There are five carpometacarpal joints in each hand. The first carpometacarpal joint (Joint of the Thumb) is a saddle shaped joint while the remaining four are all synovial ellipsoid joints. The articulation takes place between the carpus and second to fifth metacarpal bones. The joint of the thumb is described at its own separate page (Carpometacarpal Joint of the Thumb) while the remaining four are described below.
Ligaments of the carpometacarpal joints:
The following ligaments are important and must be studied with detail.
- Dorsal Ligaments: They are the strongest and connect dorsal surfaces of carpal and metacarpal bones. The second, third and fourth metacarpals have two ligaments while the fifth has only one, which is continuous with a similar palmar ligament, thus forming an incomplete capsule.
- Palmar Ligaments: They are all similar to one another except the ligaments of the third metacarpal, which are three in number.
- Interosseous ligaments: They consist of two, short, thick fibrous bands, which are limited to one part of the joint. They connect contiguous distal margins of the capitate and hamate with adjacent surfaces of the third and fourth metacarpal bones.
Synovial membranes of carpometacarpal joints:
These membranes are often continuous with the membranes of intercarpal joints.
Blood supply of carpometacarpal joints:
The second to fifth carpometacarpal joints are supplied by the posterior carpal branches of the radial and ulnar arteries, by twigs from the anterior interosseous artery, and from the palmar digital arteries.
Nerve Supply of carpometacarpal joints:
The second to fifth carpometacarpal joints are innervated by the deep terminal branches of the ulnar nerve, the anterior interosseous branch of the median nerve, and the posterior interosseous branch of the radial nerve.
Movements of carpometacarpal joints:
Slight gliding movements occur, which are effected by the long flexor and extensor muscles of the digits.