The hip is simple in it's joint configuration, but very complex in its function. Like the shoulder, it is a ball and socket joint. That means that the thigh bone has a spherical head (femoral head) that fits into a cup-like socket (acetabulum) of the pelvis. This type of joint offers high freedom of motion to allow us to get down into a squat, high kick, dance, karate, etc. Compared to the shoulder, the hip has a little less motion in order to provide stability, and the femoral head can sit deeper in the socket of the acetabulum in order to prevent dislocation.
Because the hip is ball and socket, the joint is multi-axial, meaning it can move in many many planes of motion. When the foot is not touching ground (open chain) these actions are:
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