There are eight small carpal bones in the wrist that are firmly bound in two rows of four bones each. The five long, thin metacarpal bones of the palm extend from the carpus to each of the digits of the hand. Each of the digits of the hands contains 3 phalanges except for the thumbs that contain only 2.
More than 30 individual muscles in the hand and forearm work together to achieve these diverse movements. These muscles provide the hands with flexibility, extremely precise control, and gripping strength that are necessary for activities ranging from writing and typing to producing music and gripping a ball in sports. Muscles in the forearms flex and extend the phalanges by pulling on long tendons that run through the wrist and hand.
The muscles of the hand can be broken down into three main regions: the thenar(lateral or thumb side of the palm), hypothenar (medial or little finger side of the palm) and intermediate (middle of the hand) muscles.
The ligaments are tough bands of connective tissue that connect the bones to support them and keep them in place. Important ligaments of the hand are:
- Collateral ligaments
- Volar plate
- Radial and ulnar collateral ligaments
- Volar radiocarpal ligaments
- Dorsal radiocarpal ligaments
- Ulnocarpal and radioulnar ligaments