Topographical Relationship Between the Plexus Pelvinus and Pelvic Peritoneal Reflections in Male Beagles

This study aimed to clarify the anatomical location of the plexus pelvinus in male Beagles and to determine whether the caudal end of the pelvic peritoneal reflection can offer a practical landmark for identifying this plexus. Gross anatomical examination of the pelvic cavity was performed in three male Beagle cadavers by sequential dissection from a lateral approach. The fossa pararectalis, excavatio rectogenitalis, excavatio vesicogenitalis, and excavatio pubovesicalis were identified by direct examination of the pelvic peritoneum and its reflections, and spatial relationships to the N. hypogastricus, N. pelvinus, plexus pelvinus, and rectal branches were assessed. The morphology of the pelvic peritoneum was similar in all specimens, and all four recesses were consistently identified. The plexus pelvinus was formed by convergence of the N. hypogastricus and N. pelvinus and was located beneath the parietal peritoneum facing the excavatio rectogenitalis and fossa pararectalis at the level of the prostata. The cranial end was at the level of the ampulla ductus deferentis and the caudal end was at the caudal end of the prostata. Rectal branches coursed caudally beneath the parietal peritoneum along the excavatio rectogenitalis and entered the rectum from the ventral aspect. These findings indicate that, in male Beagles, the excavatio rectogenitalis and prostata represent practical anatomical landmarks for identifying the plexus pelvinus and provide a clearer anatomical basis for topographical interpretation of the male canine pelvis.