The hip is a ball-and-socket joint that connects the lower limb to the pelvic bone, allowing a wide range of motion while providing stability and supporting the body’s weight. The hip joint is made up of bones, cartilage, muscles, ligaments, tendons, nerves, and blood vessels.
The hip’s structure allows it to perform a variety of movements, including flexion, extension, abduction, adduction, internal rotation, and external rotation. It plays a crucial role in activities such as walking, running, and jumping. However, its function can be affected by conditions such as osteoarthritis, fractures, and bursitis.
Bones: The hip joint involves the following bones:
Femur: The femur is the longest bone in the body and forms the upper part of the hip joint. It consists of a rounded head that articulates with the acetabulum of the pelvis, forming a ball-and-socket joint.
Pelvis: The pelvis is a ring-like structure formed by the fusion of several bones, including the ilium, ischium, and pubis. The acetabulum, a cup-shaped socket, is located in the pelvis and articulates with the femur.
Muscles: The muscles around the hip joint are responsible for its movement and stability. The major muscles of the hip include:
Gluteus maximus: Located in the buttocks, the gluteus maximus is the largest muscle of the body. It extends the hip joint, allowing us to stand up from a sitting position or move the thigh backward.
Gluteus medius and minimus: These muscles are situated on the lateral side of the hip. They assist in hip abduction (moving the leg away from the midline of the body) and stabilization of the pelvis during walking.
Iliopsoas: This muscle group includes the iliacus and psoas major muscles. They flex the hip joint, bringing the thigh towards the abdomen.
Adductor muscles: Located on the inner side of the thigh, the adductor muscles (adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus) help in hip adduction, bringing the leg toward the midline of the body.
Hamstring muscles: The hamstring muscles (biceps femoris, semitendinosus, and semimembranosus) are located at the back of the thigh. They flex the knee joint and also assist in hip extension.
Quadriceps femoris: Comprising the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius, the quadriceps femoris muscle group extends the knee and also assists in hip flexion.
Ligaments: Ligaments are strong bands of connective tissue that stabilize the hip joint. The main ligaments of the hip include:
Iliofemoral ligament: Also known as the Y-shaped ligament, it is the strongest ligament in the body. It connects the pelvis (ilium) to the femur, providing stability and limiting hyperextension of the hip joint.
Pubofemoral ligament: This ligament connects the pubic bone to the femur. It supports the front of the hip joint and prevents excessive abduction.
Ischiofemoral ligament: Located posteriorly, this ligament connects the ischium to the femur. It reinforces the back of the hip joint, restricting excessive internal rotation.
Nerves and Blood Vessels: The hip is supplied by nerves from the lumbar and sacral plexuses, including the femoral, sciatic, and obturator nerves. The main blood supply to the hip joint is provided by the medial and lateral circumflex femoral arteries, branches of the femoral artery.
Fascial Compartments: Fascia is a fibrous connective tissue that separates and compartmentalizes various structures. In the hip region, several fascial compartments exist:
Anterior compartment: This compartment contains the hip flexor muscles, including the iliopsoas, sartorius, and rectus femoris.
Medial compartment: It consists of the adductor muscles, which perform hip adduction.
Posterior compartment: This compartment contains the gluteal muscles, including the gluteus maximus, gluteus medius, and gluteus minimus.