ERICH SCHREMPP / SCIENCE PHOTO LIBRARY ERICH SCHREMPP / SCIENCE PHOTO LIBRARY
Human hand. X-ray of a healthy human hand, showing its bones and a faint image of the surrounding flesh. Bones of the hand consist of eight small carpals in the wrist (lower centre), which arti- culate with the two long bones of the forearm. 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 thumb which gives humans an opposable thumb. This well-adapted hand, along with an upright posture, allowed our ancestors to use tools, facilitating human evolution.
Model release not required. Property release not required.