Cross section of the femur bone viewed under polarized light showing the thick layer of medullary bone within the medullary cavity. Disclaimer: AAAS and EurekAlert! are not responsible for the ...

The three images are cross sections of femurs from a marsupial (the Virginia opossum, left), a placental (the eastern chipmunk, center) and a 66-million-year-old multituberculate fossil (right). The ...

The femur — your thigh bone — is the largest and strongest bone in your body. When the femur breaks, it takes a long time to heal. Breaking your femur can make everyday tasks much more difficult ...