There are two hip bones, one on the right and one of the left. The hip bones are categorized as innominate bones and they are two irregularly shaped bones that form part of the pelvic girdle which connects the axial skeleton to the lower limbs.

The posterior aspect of the pelvis is also the terminal portion of the vertebral canal and it is composed of the sacrum. This is the largest bone in this region and its thickness aids its function of supporting and transmitting the weight of the body.

The segment of the vertebral column that is more commonly known as the tail bone is the coccyx. The coccyx is the terminal portion of the vertebral column and is composed of four vertebrae that have fused to form a single triangular shaped bone.

While the sciatic foramina is not a bone, it has been included in this chapter as it takes shape due the the position of the bones and the ligaments in this region.

The sacrotuberous ligament and sacrospinous ligament help define the borders of this foramina through which important structures pass.