The hip joint is a simple ball and socket joint. A ball-shaped piece of bone fits inside a socket, allowing movement in many directions.
- The ball, or femoral head, is at the top of the thigh bone
- The socket, or acetabulum, is in the pelvic bone
The surfaces of the hip joint are covered with a smooth, cushioning layer called articular cartilage. A slippery liquid called synovial fluid allows the two adjoining bones to move smoothly.
The ball and socket join in the hip to help keep the hip stable. A layer of cartilage, called the labrum, surrounds the socket and provides more depth and stability. The hip is also surrounded by a joint capsule, which adds even more stability.
The hip is one of the largest joints in the body and absorbs a lot of stress during our daily activities, such as walking running or jumping.
Some of the strongest muscles in the body attach around the hip joint, enabling us to do all these activities.