The hip bone, also known as the os coxae or innominate bone, is a large flat bone located in the pelvic region of the body. It is composed of three parts: the ILIUM, the ischium, and the pubis. The ILIUM is the uppermost part of the hip bone and is the largest of the three parts. It is connected to the sacrum at the back and the iliac crest at the front. The iliac crest is the curved ridge that runs along the top of the ILIUM. The ischium is the lowermost part of the hip bone and is located at the back. It is connected to the ischial tuberosity, which is a bony protrusion that provides support when sitting. The pubis is the middle part of the hip bone and is located at the front. It is connected to the pubic symphysis, which is a joint between the two pubic bones. The ilia are four small bones located at the sides of the hip bone. They are connected to the iliac crest and provide stability to the hip joint.