Hip joint and its intracapsular ligaments
The hip joint (Latin: articulatio coxae) is an articulation formed between the acetabulum of the hip bone (Read more!) and the head of the femur (Read more!). Therefore, the hip joint connects the pelvic girdle to the free lower extremity. It is a synovial joint and is classified as the ball-and-socket joint.
In the joint, the following structures articulate:
- Articular surface of the femoral head
- Lunate surface of the acetabulum
- Acetabular labrum that is connected to the lunate surface and the outer edge of the transverse acetabular ligament.
The hip joint is surrounded by the articular capsule that is attached to the outer edge of the acetabulum and acetabular labrum. At the front of the femur, it is attached to the intertrochanteric line, but at the back, it attaches above the intertrochanteric crest.
Ligaments
The stability of the hip joint is increased with the help of two groups of ligaments. They are named based on their location in relation to the fibrous capsule - intracapsular ligaments and extracapsular ligaments.
The intracapsular ligaments are located inside the hip joint cavity. In contrast, the extracapsular ligaments are situated outside the capsule and are continuous with its outer surface.
The hip joint cavity contains two intracapsular ligaments:
- Transverse acetabular ligament - connects the ends of the lunate surface and passes above the acetabular notch;
- Ligament of head of femur (ligamentum teres of femur) - a small structure that runs from the acetabular notch and transverse acetabular ligament to the fovea capitis of the femoral head.