The wrist joint is a synovial type, biaxial variant joint which is formed by the distal articular surface of the radius with the articular surfaces of the scaphoid and lunate bones primarily and secondarily between the articular disc and the triquetrum. The wrist is the bridge that connects the forearm to the hand. It is actually composed of 8 carpal bones and 5 metacarpal bones. The palmar and dorsal radiocarpal and ulnocarpal ligaments secure the wrist and carpal joints. To further add to its stability, the radial and ulnar collateral ligaments also aid in securing the two joints. In between the distal and proximal rows of the carpal bones exists the intercarpal joints which contribute to wrist movement.
The reason that the wrist is so magnificent to study is that aside from being composed of 8 bones, these 8 small bones forms small joints with the bones beside it. So the wrist is actually composed of many small joints with 8 bones connecting to one another. The articular cartilage that covers the ends of the bones in the wrist are relatively thinner because it is not a weight bearing joint. Articular cartilage prevents damage to the bones by laying a thin covering that protects from friction. Another function aside from providing a slippery relief from friction is that the articular cartilage assumes another role as a shock absorber.
An opening between the hamate and trapezium bone provides a canal for the flexor tendons to the thumb and fingers together with the median nerve. This canal is also referred to as the carpal tunnel and significant injury or compression to the median nerve housed in the carpal tunnel can produce numbness to three radial fingers and thumb weakness.
A proximal and distal row arises as the carpal bones are organized into two groups. No tendons insert upon the proximal carpal row so for this reason, the bones present as an intercalated segment. Because of all of these underlying reasons, the movement solely relies on mechanical forces from the bones that meet. Intercarpal ligaments make the bones in the distal row at proximity or close to each other. The carpometacarpal joint arises from the bones of the distal row attaching to the metacarpal bones.
Hand movements involve movements of the metacarpophalangeal and interphalangeal joints primarily and secondarily among the carpometacarpal and intermetacarpal joints.
When you finally get a view on how diversely we use our hands and wrist, you get an idea of how difficult life will be without these magnificent tools. Because the wrist and hands are so complex and made up of several bones, they are prone to injury and damage. Basic anatomy knowledge makes us all aware of the fragile the most used part of the body is.