This cavity, is bounded by, but excludes: superiorly an artificial plane that extends from the symphysis pubis to the superior iliac crests; inferiorly the inferior aperture of true pelvis and pelvic diaphragm; and laterally the pelvic wall. The bony pelvis extends superiorly with the ilia, which anteriorly are incomplete, presenting a wide interval between the anterior borders of the ilia. The volume can be divided into the superior cavity of false pelvis and the inferior cavity of true pelvis. Note, the contents and structures that form the boundaries are excluded from the cavity.