CNRI / SCIENCE PHOTO LIBRARY CNRI / SCIENCE PHOTO LIBRARY
Adult hand bones. Coloured X-ray of the healthy hand of an adult, showing the bone arrangement. An outline of the flesh is seen. Bones of the hand consist of eight small carpals in the wrist (centre left), which articulate with the two long forearm bones (far left). Five metacarpal bones (at centre) make up the palm of the hand. Each finger has three phalanges, except the thumb which has two such bones. This skeleton enables the human hand to be used with great flexibility, helped especially by the joint between the wrist and the opposable thumb. This well-adapted hand allowed our ancestors to use tools, facilitating human evolution.
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