The top of the thigh bone or femur is called the femoral head. It is a rounded ball of bone that is covered by smooth gliding cartilage called articular cartilage. It fits in to the socket of the hip joint called the acetabulum. The femoral head is connected to the thigh bone by a section of bone called the femoral neck.
The round ball-shaped proximal end of the Femur that articulates with the socket formed by the ischium, pubis, and acetabulum (joined together by the triradiate cartilage). image image image image