In anatomy, the hip is the bony projection of the femur which is known as the greater trochanter, and the overlying muscle and fat. The hip joint is the joint between the femur and acetabulum of the pelvis and its primary function is to support the weight of the body in both static (e.g. standing) and dynamic (e.g. walking or running) postures.
The hip bones are divided into 5 areas, which are:
The sacrum: This is a bone at the base of the vertebral column that is created by the fusion of 4 vertebrae. It attaches to the ilium on the sides. It also provides a point of muscle attachment for back muscles.
The coccyx (also called the tail bone): This is a small bone that attaches to the base of the sacrum. It is created from the fusion of 4 small vertebrae.
The ilium: This is the largest area of the hip bones. It consists of 2 large broad plates, one on each side, which serve to support the internal organs, and to provide attachment for muscles of the back, sides, and buttocks. The hip joint of the femur is part of the ilium.
The ischium: The ischium consists of 2 broad curves of bone, one on each side, which lie below the ilium, and are attached to the pubis in the front and the ilium in the back. The ischium serves as a place of attachment for muscles. When a person's butt hurts from sitting on a hard surface, it is the result of the sharp ischium pressing on the buttocks.
The pubis: The pubis is the front-most area of the hip bones. It attaches to the ilium on the sides and the ischium on the bottom. It provides structural support, and serves as a place of attachment for the muscles of the inner thigh.
©2014 Charles Pesson, MD