The hip joint is a very large and flexible joint with a wide range of motion since it is a ball and socket joint. The rounded ball is at the top of the femur or thigh bone. This femoral head is enclosed by a cup-shaped socket created by the pelvic bone known as the acetabulum.
The surfaces of the ball and socket are covered by a material known as the articular cartilage, which is made of hyaline. This hyaline cartilage cushions the bones and acts as a shock absorber. It also allows them to move smoothly.
Ligaments, which are strong bands of tissue, connect the ball to the socket and keep the hip joint steady. Other ligaments surround the joint and ensure that it rarely dislocates even after severe trauma.
The ball and socket of the hip joint is also surrounded by a tough, fibrous capsule which helps keep the bones in their correct position. This capsule is lined by synovium, which produces the synovial fluid that lubricates the joint and ensures that the bones do not rub against each other as they move. This fluid also nourishes the articular cartilage.
The hip joint is also encircled by many muscles, which help hold it together and prevent disarticulation. These muscles also power the joint and allow it to move by rotating it (turning it around), flexing it and extending it (moving it forward and backward). These muscles which include gluteus maximus, medius and minimus are attached to the joint by tendons.
Written by: Marian Kim, FizzNiche Staff Writer