Photograph of the skeleton of the left human hip (coxal) joint, viewed in posterior aspect. The spheroid femoral head forms a strong ball-and- socket joint with the acetabulum (hip socket). The joint is partially disarticulated in this specimen. The large projection on the left of the femoral head is the greater trochanter, on which ligaments are anchored that bind the femur to the ilium, the upper bone of the pelvis.