The hip joint is located in the body where the trunk meets the legs. It is comprised of the bones, tendons, ligaments and muscles. This joint is involved in the majority of everyday movements and activities such as walking, sitting and standing and acts as a stabilising structure when weight bearing.
The head of the femur and pelvis are the bones that make up the hip joint making a ball and socket joint. The pelvis is comprise of three bones fused together; the Ilium, Ischium and Pubic bone.. A ball and socket joint is where one rounded surface of the bone moves within a depression of another bone.
The ligaments that attach bone to bone provide stability to the structure for the hip and are classified as either intracapsular and extracapsular. The intracapsular ligament is the ligamentum teres . There are three extracapsular ligaments; Iliofemoral ligament, Pubofemoral and Ischiofemoral. Attached to these ligaments are muscles, there are however other muscles that also contribute to the movement of the hip.
The major muscles that contribute to the movement of the hips are gluteus maximus, gluteus medius, piriformis, iliopsoas, rectus femoris, semitendinosus, biceps femoris, tensor fascia latae.
Each muscle group creates different movements at the hip and also supports the motions that they are associated with.
- When moving the hip into flexion the iliopsoas, rectus femoris, sartorius, pectineus are the muscles involved in creating the movement. The degree to which flexion at the hip can occur depends on whether the knee is flexed, this relaxes the hamstring muscles, and can increases the range of flexion that can be achieved. An example for thus type of movement is stepping.
- To extend the hip joint; gluteus maximus, semimembranosus, semitendinosus and biceps femoris (the hamstrings) are involved. Extension at the hip joint is limited by the joint capsule and the iliofemoral ligament. These structures become taut during extension to limit further movement. What this movement would look like is going from siting down to standing up.
- With Abduction of the hip; gluteus medius, gluteus minimus, piriformis and tensor fascia latae promote movement. An example for this movement is stepping o the side.
- Adduction of the hip requires the adductors longus, brevis and magnus, pectineus and gracilis to promote this movement.
- External rotation of the hip involves the biceps femoris, gluteus maximus, piriformis, assisted by the obturators, gemilli and quadratus femoris. The most common movement that utilises external rotation is stretching of the glute muscles.
- Internal rotation of the hip involves the anterior fibres of gluteus medius and minimus, tensor fascia latae. An example of this movement is preforming the step across as part of a grape vine step.