Image: Upper leg bone of a modern human

Upper leg bone of a modern human

Cast of a upper leg bone (femur) of a modern human.

This  bone shows the structure of the femur of an upright walker or bipedal animal. The ball joint, the part that joins the pelvis, sits directly over the outside of the knee. (Quadrupedal animals have femurs in which the ball joint, the part that joins the pelvis, sits directly over the inside of the knee.) The angle subtended by the femur at the knee in bipedal walkers is greater than that of quadrupedal walkers. This results in the inner bump of the knee joint being longer than the outer bump.
 

Photographer:
Stuart Humphreys
Rights:
© Australian Museum

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