About Your Hip
The hip is one of the body's largest weight-bearing joints.
The Healthy Hip Anatomy
The hip joint is a ball-and-socket joint consisting of the thigh bone (femur) and a rounded socket (acetabulum). The top of the femur is shaped like a ball and is referred to as the femoral head. The femoral head fits into the acetabulum to form the joint.
The joint space between the femoral head and the acetabulum is filled with fluid, which allows the hip head to slide smoothly inside the socket with every movement. In a healthy hip, articular cartilage covers the bone surfaces of the hip joint. Cartilage is a rubbery tissue that acts as a cushion and gliding surface to allow smooth movement within the joint. Thin, smooth tissue called synovial membrane covers all remaining surfaces of the hip joint. In a healthy hip, synovial membrane produces a small amount of fluid that lubricates the joint to reduce friction.
Ligaments are soft tissue structures that connect bone to bone. A joint capsule is a watertight sac that surrounds a joint. In the hip, the joint capsule is formed by a group of three strong ligaments that connect the femoral head to the acetabulum and provide stability to the joint.
The gluteals make up the muscles of the butt on the back of the hip and are the key muscles for keeping the pelvis level as you walk. The inner thigh is formed by the adductor muscles which function to pull the leg inward toward the other leg. The muscles in front of the hip joint function to flex the hip, and the muscles in the back of the thigh function to extend the hip, pulling it backward. Smaller muscles going from the pelvis to the hip help to stabilize and rotate the hip.