Figure 8 shows the structure of the femur, or thighbone. femur, which is the body's longest bone, connects the pelvic bones to the lower leg Notice that a tough membrane covers all of the bone except the ends Blood vessels and nerves enter and leave the bone through the membrane. Beneath the bone's outer membrane is a layer of compact bone, which is hard and dense, but not solid. As you can see in Figure 8, small canals run through the compact bone. These canals carry blood vessels and nerves from the bone's surface to the living cells within the bone