Hip bones and thigh muscles. Artwork of a frontal (anterior) view of the left hip, showing bones and some thigh muscles (red). At lower right is the femur (thigh bone). The head of the femur (ball-shaped) is covered in cartilage (grey) that cushions it in the acetabulum, the hip socket in the pelvis. The pelvis bones that form part of the hip joint are the ischium and pubis (centre left) and the ilium (upper centre). At top left are bones of the lower spine (coccyx, sacrum, lumbar vertebrae). The muscles shown are attached to the tuberosity of the ischium. These include the adductor magnus and the hamstring muscles (biceps femoris, semimembranosus, semitendinosus).