Os Coxæ

The os coxæ (or os innominatum) forms the skeleton of the hip or haunch, and is the largest of the flat bones. It consists primarily of three parts, the ilium, ischium, and pubis, which meet to form the acetabulum, a large cotyloid cavity for articulation with the head of the femur. These parts are fused at about one year of age, but it is convenient to describe them separately.