Clinical anatomy of the pelvic floor.
The study presented here comparing cross-sectional anatomy of the fetal and the adult pelvic connective tissue with the results of modern imaging techniques and actual surgical techniques shows that the classical concepts concerning the subdivision of the pelvic connective tissue and muscles need to be revised. According to clinical requirements, the subdivision of the pelvic cavity into anterior, posterior, and middle compartments is feasible. Predominating connecting tissue structures within the different compartments are: Paravisceral fat pad within the anterior compartment (Fig. 17, I), rectal adventitia or perirectal tissue within the posterior compartment (Fig. 17, II), and uterosacral ligaments within the middle compartment. The nerve-vessel guiding plate can be found in all of these compartments; it starts within the posterior compartment and it ends within the anterior one. It constitutes the morphological border between the anterior and posterior compartments in the male. This border is supplied by the uterosacral ligaments in the female. Whereas in gross anatomy no further border is discernable between anterior and posterior or middle compartment, the rectal fascia (hardly visible in embalmed cadavers) demarcates the rectal adventitia and is one of the most important pelvic structures for the surgeon. In principle, the outlined subdivision of the pelvic connective tissue is identical in the male and in the female; facts that become clear from early human life and that are already established during this period (Fig. 18). The uterus is interposed between the bladder and rectum and subdivides the pelvic peritoneum into two pouches thus establishing the only real difference between male and female pelvic cavity. The preferential direction of the pelvic connective tissue fibers is not changed by the interposition of the uterovaginal complex. The pelvic floor muscles are composed of the portions of the levator ani muscle, the muscles of the cavernous organs and the deep transverse perineal muscle in the male. The latter does not exist in the female. We have clearly shown that the different muscles can already be found in early human life and that they are never intermingled with the muscular walls of the pelvic organs. The levator ani muscle of the female, however, is intermingled with connective tissue long before the female sexual hormones exert influence. We have also shown that the distinct sexual differences within the pelvic floor muscles as well as within the sphincter muscles can already be found in early human life. Both the external urethral and the external anal sphincter muscles are not completely circular. The external anal sphincter is intimately connected with the internal sphincter as well as with the longitudinal muscle. Whereas the innervation and function of the urethral sphincter muscles are mostly clear, cloacal development, innervation, and function of all parts of anal sphincter complex are not completely clarified. As to the support of the pelvic viscera, we believe that intact pelvic floor muscles, an undisturbed topography of the pelvic organs, and an undisturbed perineum are of more importance than the so-called pelvic ligaments. Our hypothesis points to the fact that the support of pelvic viscera is multistructural. Thus in pelvic surgery, a lot of techniques have to be revised with the aim to preserve or to reconstruct all the structures mentioned. This is a multidisciplinary task that can only be solved by cooperation of morphologists, urologists, gynecologists, and coloproctologic surgeons or by creating a multidisciplinary pelvic floor specialist.