Visceral branches of the inferior hypogastric plexus: a cadaveric and immunohistochemical study

The inferior hypogastric plexus, also known as the pelvic plexus, represents an important autonomic structure of the lesser pelvis, providing sympathetic and parasympathetic innervation to the pelvic viscera. This study aimed to investigate the detailed morphology, topography, and neural composition of its branches and secondary plexuses, including the vesical, prostatic, middle rectal, and uterovaginal plexuses, with particular emphasis on their terminal visceral branches and their anatomical variability.

A total of 50 formalin-fixed human cadavers were examined using macroscopic dissection and analysis performed under an operating microscope. Special attention was paid to surgically relevant structures, including the Walsh bundle. Immunohistochemical techniques were employed to characterize adrenergic and cholinergic fiber components within the examined structures.

Adrenergic fibers were predominantly associated with periarterial pathways, whereas cholinergic fibers typically coursed independently of vascular structures. Contrary to some prior reports, the vesical plexus did not contribute fibers to the prostatic plexus; both plexuses were most often identifiable as distinct and independent nerve bundles. The vesical plexus showed a predominance of cholinergic fibers, while the prostatic plexus was mainly adrenergic. Rectal nerves within the mesorectum were largely cholinergic, with increased adrenergic contribution distally and convergence with somatic pudendal motor fibers. In females, the uterovaginal plexus followed the uterine artery, with predominantly adrenergic fibers in the vaginal part and mixed innervation in the uterine part.

These findings may provide clinically relevant insights for nerve-sparing pelvic surgery and the prevention of iatrogenic damage, while offering an updated perspective on the functional organization of the autonomic innervation of the pelvis.