This cross-sectional segment is bounded superiorly by a virtual horizontal plane at the level of the junction between T8 and T9 (and thus also includes part of the thoracic volume below this level); and inferiorly it extends to the perineum, including the volume of the true and false pelvic cavities and part but not necessarily the entire external genitalia. The volume includes the entire transverse thickness of the body over the longitudinal extent between the superior (upper) and inferior (lower) boundaries including the skin and subcutaneous tissue. The segment relates to the cross-sectional or projectional volume as perceived by transmissive or emissive imaging.