The extrinsic hand muscles are located in the forearm where their bellies form the proximal fleshy roundness. The wrist consists of diverse muscles, tendons and bones, including the eight carpal bones, the radius and the ulna. The anatomical structures perform very powerful activities or fine delicate microscopic movements.
The human hand has five fingers and 27 bones, not including the sesamoid bone, the number of which varies between people, 14 of which are the phalanges (proximal, intermediate and distal) of the fingers. The metacarpal bones connect the fingers and the carpal bones of the wrist. Each human hand has five metacarpals and eight carpal bones. Among humans, the hands play an important function in body language and sign language.