Anatomic and clinical evidence of intrapelvic pudendal nerve and its relation with striated sphincter of the urethra

OBJECTIVE: To demonstrate that somatic innervation of the urethrae striate sphincter is intrapelvic and not through an internal pudendal nerve, an extrapelvic nerve in its entire path. To study the relationship of the pelvic plexus with genito-urinary organs and its surgical implications. METHODS: 6 embryos and 2 fetuses, sliced and stained with techniques suitable for nervous structures were studied. Sequential observation of the pelvic plexus structures and the internal pudendal nerve was carried out using light microscopy. Three-dimensional reconstruction of the two fetuses was performed to study the relationships of these structures with the genito-urinary organs. RESULTS: A nervous branch was identified in the 19, 25 and 30 mm long specimens that started at the internal pudendal nerve and joined the hypogastric ganglion close to the site of pelvic nerves binding. Hypogastric ganglion efferent branches penetrating the striate sphincter after a short descendent run were seen in the 30 and 39 mm embryos. CONCLUSIONS: Our findings confirm that the urethrae striate sphincter received the autonomous and somatic innervation from the pelvic plexus and, therefore, is susceptible to damage during cancer related surgery of the pelvic organs. An improved knowledge of these structures and the use of nerve preservation surgical techniques can reduce the incidence of post-operative incontinence in this type of surgery.