The femur (/ ˈ f iː m ər /, pl. femurs or femora / ˈ f ɛ m ər ə /), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrate, the largest bone of the human geishax.xyz head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with the tibia and kneecap, forming the knee joint. The femur of an adult male is about 19 inches long and a bit under an inch in diameter. The proximal end of the femur (the part closest to the heart) is the head of the femur. The head of the femur is a ball that makes up part of the hip joint. It allows the leg to move at all angles.
The femur extends from the hip to the knee and represents one fourth of the height of the average adult. You can feel the lower end of the femur at the knee. The upper end is deeply buried in the muscles at the hip, but you can feel the bony bump of the greater trochanter on the outer side of the hip. The femur is a very large, strong bone that is difficult to break. A broken femur is usually caused by a severe accident; vehicle accidents are one of the primary causes. Older adults can fracture.
The average adult male femur is 48 centimeters ( in) in length and cm ( in) in diameter and can support up to 30 times the weight of an adult.  It forms part of the hip joint (at the acetabulum) and part of the knee joint, which is located above.