Tomographical anatomy of the pelvis, pelvic floor, and related structures.

The sectional anatomy of the pelvic floor was studied in plastinated sections of adult pelves by computed tomography and by magnetic resonance imaging. In sectional anatomy, the levator ani is composed of three portions that can be clearly distinguished by their planes of cleavage and by the course of their fiber bundles. No muscular connections are found between the levator ani portions and the pelvic organs. The fascia of the levator ani in always interposed between the muscle and the pelvic organs. The sectional anatomy of the sphincter ani externus reveals a subdivision into a subcutaneous and a deep portion. Although the puborectalis portion of the levator ani and the deep portion of the sphincter ani externus are more or less continuous, in sectional anatomy they can be distinguished due to their different origins and attachments.