The hip is the largest weightbearing joint in the body. It is a ball-and-socket supported by muscles, capsular ligaments and tendons.
Learn more about the bones, muscles, ligaments, tendons, blood vessels and nerves that make up the hip below.
All of the anatomical parts below work together to flex, extend, abduct, adduct, and rotate the hip. Disorders of any of these structures can create pain, dysfunction, and movement problems.
Bones and Joints
The hip is the joint at which the femur (thigh bone) joins the pelvis. The joint is a ball and socket. The ball is the head of the femur bone, and the socket is called the acetabulum. The deep circular acetabulum is actually where the three bones of the pelvis (the ilium, ischium, and pubis) meet and fuse in teenage years. Lining the acetabulum and head of the femur is smooth cartilage which helps the hip glide and rotate without pain.
Labrum
The labrum is a circular, fibrous cartilage ring that lines the edge of the hip socket. It has an important role in providing stability to the hip joint and forming a seal around the head of the femur. The hip and the shoulder are the only two joints that have a labrum.
Ligaments
Ligaments are strong fibrous tissue that connect bones to other bones. The hip capsule which surrounds the hip joint and supports it is actually three ligaments combined together.
These three ligaments are:
Iliofemoral Ligament - a Y-shaped ligament at the front of the hip. It helps limit overextension and rotation. It is the thickest ligagment in the body!
Pubofemoral Ligament - a Triangular shaped ligament on the inner part of the hip joint which connects the pubis bone to the femur.
Ischiofemoral Ligament - a ligament on the back side of the hip
There is also a small, round ligament called the Ligamentum Teres that connects the femoral head to the acetabulum. It is not involved in hip movement but has an important role in the infant hip, as it supplies blood to the head of the femur bone.
Muscles and Tendons
Tendons connect muscles to bone. There are several important tendons around the hip which attach the strong muscles of the pelvis and thigh to the hip bones.
Gluteal Muscles - also known as the buttocks, these three muscles (gluteus minimus, gluteus medius, and gluteus maximus) are very important for hip stability. They originate on the back of the pelvis and insert on the side of the hip at the greater trochanter.
Adductors - the three adductor muscles on the inside of the thigh work together to pull the leg towards the midline. Tears and inflammation in the adductor tendons can create hip and groin pain.
Ilipsoas - this deep, strong muscle runs from the low back, through the pelvis all the way to the inside of the thigh to attach below the head of the femur. The iliopsoas is a powerful hip flexor which can quickly become irritated when the hip has disease.
Rectus Femoris - This muscle on the front of the thigh works with the iliopsoas to flex the hip
Hamstrings - these three muscles (semimembranosus, semitendinosus, and biceps femoris) run from the back side of the pelvis down to the knee. The are able to extend the hip and also flex the knee.
Nerves and Arteries
Nerves are the conduits that transfer signals to and from the brain about pain, movement, touch, and temperature. The sciatic nerve in the back of the hip and the femoral nerve in front of the femur are the two largest nerves in the thigh. Smaller nerves include the obturator nerve, and lateral femoral cutaneous nerve (LFCN).
Blood vessels also pass through the hip to supply the lower limbs. The femoral artery is one of the largest arteries in the body and passes from the pelvis into the upper thigh to supply the leg.