As mentioned previously, the hip bone is the largest bone from the ones that form the bony pelvis. It is also known as the coxal bone (from Latin os coxae), pelvic bone, and innominate bone. The hip bone is irregular-shaped and composed of three smaller bones that fuse together - ilium, ischium, and pubis.
- The ilium is the largest uppermost bone, forming the massive upper wing-like portion.
- The ischium is the curved anteroinferior and posteroinferior portion.
- The pubis is the curved most anterior segment.
All three bones completely fuse during early adolescence. They meet at the acetabulum - a central cup-shaped fossa found on the lateral surface of the bone. It articulates with the head of the femur, forming the hip joint. Both hip bones meet anteriorly at the pubic symphysis, and posteriorly they connect with the sacrum at the sacroiliac joints.