Your hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the pelvis. The ball is the femoral head, which is the upper end of the femur (thigh bone). The surface of the ball and socket is covered with cartilage, a smooth, coating layer that protects the bones and enables them to glide easily across each other. The acetabulum is ringed by strong fibrocartilage called the labrum. The labrum, often referred to as the “gasket” of the ball and socket joint, forms a seal around the socket, creating a tight suction and helping to provide stability to the joint.