Hand and Wrist
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The wrist is a complex series of 20 articulations binding 15 bones, acting as a universal joint that moves through multiple axes of motion. The motion of the wrist allows positioning of the hand freely in space. Load is transmitted from the hand to the forearm through the 3 columns of the wrist. To ensure stability, ligaments acts as checkreins in a series of rings which span from the distal radius to the hand.
Fingers (digits) are composed of three bones; the proximal, middle and distal phalanges. The thumb is composed of a proximal and distal phalanx. There are broadly-speaking two sets of muscles that control motion; the intrinsic (arising from within the hand) and the extrinsic (arising from the forearm). Tendons arise from these muscles. There are a complex array of flexor and extensor tendons that control motion of the digits. The flexor tendons are contained by pulleys, which prevent bowstringing of the tendons off the bones of the digits.
