Introduction Little detailed information is available concerning autonomic and somatic nerve supply to the clitoris, potentially causing difficulties for nerve preservation during pelvic and perineal surgery. Aim To identify the location and type (nitrergic, adrenergic, cholinergic and sensory) of nerve fibers in the clitoris and to provide a three-dimensional (3D) representation of their structural relationship in the human female fetus. Methods Serial transverse sections were obtained from five human female fetuses (18–31 weeks of gestation) and subjected to histological and immunohistochemical investigations; digitized serial sections were used to construct a 3D representation of the pelvis. Main Outcome Measures Pelvic-perineal nerve location and type were evaluated qualitatively. Results The female neurovascular bundle (NVB) is the anteroinferior terminal portion of the inferior hypogastric plexus that runs along the postero-lateral then lateral face of the vagina and is rich in nNOS-positive fibers. The cavernous nerve (CN) is a thin ventrocaudal collateral projection of the NVB, and this projection does not strictly follow the NVB course. The CN runs along the lateral surface of the vagina and urethra and penetrates the homolateral clitoral crus. The CN provides adrenergic, cholinergic, and nitrergic innervation to the clitoris, but not sensory innervation. The spongious nerve (SN) is the terminal and main projection of the NVB and provides nitrergic innervation to the vestibular bulbs. The dorsal clitoris nerve (DCN), somatic branche of the pudendal nerve, runs along the superior surface of the clitoral crus and body and has a segmental proerectile nitrergic activity related to communicating branches with the CN. Conclusions “Computer-assisted anatomic dissection” allowed the identification of the precise location and distribution of the autonomic and somatic neural supply to female erectile bodies, providing an anatomical basis for nerve-sparing surgical techniques, and participating to the understanding of neurogenic female sexual dysfunction.

Sphincter continence and sexual function require co-ordinated activity of autonomic and somatic neural pathways, which communicate at several levels in the human pelvis. However, classical dissection approaches are only of limited value for the determination and examination of thin nerve fibres belonging to autonomic supralevator and somatic infralevator pathways. In this study, we aimed to identify the location and nature of communications between these two pathways by combining specific neuronal immunohistochemical staining and three-dimensional reconstruction imaging. We studied 14 normal human fetal pelvic specimens (seven male and seven female, 15-31 weeks' gestation) by three-dimensional computer-assisted anatomic dissection (CAAD) with neural, nitrergic and myelin sheath markers. We determined the precise location and distribution of both the supra-and infralevator neural pathways, for which we provide a three-dimensional presentation. We found that the two pathways crossed each other distally in an X-shaped area in two spatial planes. They yielded dual innervation to five targets: the anal sphincter, levator ani muscles, urethral sphincter, corpus spongiosum and perineal muscles, and corpora cavernosa. The two pathways communicated at three levels: proximal supralevator, intermediary intralevator and distal infralevator. The dorsal penis ⁄ clitoris nerve (DN) had segmental nitrergic activity. The proximal DN was nNOS-negative, whereas the distal DN was nNOS-positive. Distal communication was found to involve interaction of the autonomic nitrergic cavernous nerves with somatic nitrergic branches of the DN, with nitrergic activity carried in the distal part of the nerve. In conclusion, the pelvic structures responsible for sphincter continence and sexual function receive dual innervation from the autonomic supralevator and the somatic infralevator pathways. These two pathways displayed proximal, intermediate and distal communication. The distal communication between the CN and branches of the DN extended nitrergic activity to the distal part of the cavernous bodies in fetuses of both sexes. These structures are important for erectile function, and care should therefore be taken to conserve this communication during reconstructive surgery.

Introduction: Knowledge of the anatomy of the male pelvic floor is important to avoid damaging the pelvic floor muscles during surgery. We set out to explore the structure and innervation of the smooth muscle of the whole pelvic floor using male fetuses. Material and Methods: We removed en-bloc the entire pelvis of three male fetuses. The specimens were serially sectioned before being stained with Masson's trichrome and hematoxylin and eosin, and immunostained for smooth muscles, and somatic, adrenergic, sensory and nitrergic nerve fibers. Slides were digitized for 3D reconstruction. Accepted Article Results: We individualized a middle compartment that contains smooth muscle (SM) cells. This compartment is in close relation with the levator ani muscle (LAM), rectum, and urethra. We describe a posterior part of the middle compartment posterior to the rectal wall and an anterior part anterior to the rectal wall. The anterior part is split into 1) a centro-levator area of SM cells localized between the right and left LAM, 2) an endo-levator area that upholsters the internal aspect of the LAM, and 3) an infra-levator area below the LAM. All these areas are innervated by autonomic nerves coming from the inferior hypogastric plexus. The core and the infra-levator area receive the cavernous nerve and nerves supplying the urethra. Conclusion: We thus demonstrate that these muscular structures are smooth and under autonomic influence. These findings are relevant for the pelvic surgeon, and especially the urologist, during radical prostatectomy, abdominoperineal resection and intersphincteric resection.