The joints of hand are:
- Intercarpal joints.
- Midcarpal joint.
- Carpometacarpal joints.
- Intermetacarpal joints.
These are plane type of synovial joints, which interconnect the carpal bones. They contain the following joints:
- Joints between the carpal bones of the proximal row.
- Joints between the carpal bones of the distal row.
- Midcarpal joint between the proximal and distal rows of the carpal bones.4) Pisotriquetral joint created between pisiform and palmar surface of triquetral bone.
The carpometacarpal joints are plane type of synovial joints with the exception of the carpometacarpal joint of the thumb, that is a saddle joint. The distal surfaces of the carpals of distal row articulate with all the bases of metacarpals. Functionally and medically, first carpometacarpal joint is the most essential carpometacarpal joint and for this reason described in detail latter.
These are plane type of synovial joints and created by the articulation of the bases of adjacent metacarpals of the fingers.
There are the following 3 joint cavities among the above-mentioned joints: Joint cavities of intercarpal, carpometacarpal, and intermetacarpal joints:
- A continuous common cavity of all intercarpal and metacarpal joints, with the exception of that of first carpometacarpal joint.
- Cavity of first carpometacarpal joint.
- Cavity of pisotriquetral joint.
Movements of the intercarpal and carpometacarpal joints.
Movements at the intercarpal, carpometacarpal (with the exception of first), metacarpophalangeal, and interphalangeal joints.
First Carpometacarpal Joint
It’s synovial joint of saddle variety.
Proximal: Distal surface of the trapezium.
Distal: Proximal surface of the base of 1st metacarpal.
Both proximal and distal articular surfaces are reciprocally concavo-convex; for this reason permit broad range of movements at this joint.
1) Capsular ligament (joint capsule): It’s thick loose fibrous sac, which encloses the joint cavity. It’s connected proximally to the margins of articular surface of the trapezium and distally to the circumference of the base of first metacarpal bone. The inner surface of the capsule is lined by the synovial membrane.
2) Lateral ligament: It’s a broad fibrous band stretching from lateral surface of the trapezium to the lateral side of the base of 1st metacarpal bone.
3) Anterior (palmar) ligament: It extends obliquely from palmar surface of trapezium to the ulnar side of the base of 1st metacarpal.
4) Posterior (dorsal) ligament: It also extends obliquely from dorsal surface of trapezium to the ulnar side of the base of 1st metacarpal.
The joints are surrounded by different muscles and tendons of the thumb. Additionally, it’s related to:
1) radial artery on its posteromedial sides.
2) First dorsal interosseous muscle on its medial side.
By radial artery.
By Median Nerve.
The different movements, which take place at the first carpometacarpal joint are as follows:
- Flexion and extension.
- Abduction and adduction.
- Medial and lateral rotation.