If you are starting to feel hip pain or stiffness, you’ll want to know more about the bones and muscles that make up the hip’s anatomy.
Hip Anatomy: Bones
The hip joint is made up of two bones: the pelvis and the femur (the thighbone). It is the largest ball-and-socket joint in your body. The "ball" is the rounded end of the femur (also called the femoral head). The "socket" is a concave depression in the lower side of the pelvis (also called the acetabulum). The femoral head fits into the acetabulum to form the hip joint. This anatomy allows for a lot of motion within the joint — for instance, walking, running, and climbing.
The femoral head attaches by way of the femoral neck to the rest of the femur. At the top of the femur, next to the femoral neck, there is another bump on the outside of your hip called the greater trochante to which muscles attach. Cartilage helps prevent friction between the femoral head and the acetabulum, but hip pain can occur if your cartilage begins to wear down or is damaged.
“I see a lot of patients who have injuries to the joint, especially to cartilage,” says Brian Parsley, MD, assistant professor in the department of orthopedic surgery at the Baylor College of Medicine in Houston, Texas.
Hip Anatomy: Muscles and Tendons
The motion of the ball-and-socket is controlled by several very powerful muscles which attach to the bones. The muscles you probably know the best are your “glutes” (gluteal muscles), the large, strong muscles that attach to the back of your hip bones and comprise the buttocks.
“The glutes attach to your greater trochanter; those muscles help hold your pelvis and your body up so you don’t fall over and also help you walk,” says Dr. Parsley. “On top of that layer of muscle is the iliotibial band, which starts at the brim of your pelvis outside the hip joint and runs down your leg.”
If the iliotibial band (a long tendon that many muscles in your hip and leg attach to) becomes too tight or overused, this can contribute to hip pain.
Some of the other muscles in the hip are:
- Adductor muscles on the inside of your thigh.
- Iliopsoas muscle, a hip flexor muscle that attaches to the upper thigh bone.
- Rectus femoris muscle, one of the quadriceps muscles on the front of your thigh.
Muscles play an important role in the health and well-being of your hip. All these muscles work together to provide you with range of motion in your hip while keeping your body stable and upright. “The underlying recommendation for preventing hip pain would be to try and maintain flexibility and muscle tone,” Parsley says.
Hip Anatomy: Pain Sources
General causes of hip pain include:
- Muscle strain
- Bone fracture (such as a fracture of the femoral neck)
- Bone spurs or other malformations of your hip
Parsley also sees a lot of patients with bursitis of the hips. This condition is caused when bursae, small fluid-filled sacks that act as cushions in parts of your body where there is friction between muscles, bones, and tendons, become inflamed or damaged from injury or infection.
One of the most common forms of bursitis is trochanteric bursitis (pain on the outside of your hip), but there are bursae in other parts of your hip as well. For example, there is one under the iliopsoas muscle in the front of your hip.
The hip is a complicated mechanism and therefore hip pain can originate in many different parts of the joint. Learning the anatomy of your hip will better enable you to pinpoint your pain and work with your doctor to keep it from limiting your life.