Functional Anatomy The hip joint is a ball and socket joint formed between the head of the femur (thigh bone) and the hip socket (acetabulum). The important parts of the hip are:- Ball and Socket Joint - The joint between the head of the femur and the acetabulum (socket) of the pelvis. Joint Capsule - flexible sac around the joint allowing a wide range of movements. The capsule keeps in place the lubricating synovial fluid. Greater Trochanter - the attachment point for many of the buttock muscles (hip abduction and external rotation) Lesser Trochanter - the attachment of iliopsoas muscle (hip flexion) Hip Movements - in the standing position Flexion - move your leg forwards. Extension - move your leg backwards. Abduction - move your leg away from your side. Adduction - move your leg towards to other leg. Internal Rotation - rotate your foot towards the other (toes pointing towards each other). External Rotation - rotate your foot away from the othe