Innervation and histology of the clitoral-urethal complex: a cross-sectional cadaver study.

Introduction: Despite its central role in sexual function, we lack a description of the nerve distribution and histology for the central components of the clitoris.

Aim: This study aims to characterize microscopic anatomy of the clitoral-urethral complex (CUC) and aid our understanding of sexual sensation

Methods: The CUC was excised from three female fresh-frozen cadavers en bloc and prepared in 5-μm longitudinal sections with hematoxylin and eosin and S100 immunohistochemistry for neural elements. Approximately 20 sections were obtained from each specimen. On low power microscopy, the 30 most innervated fields on each section were identified. On high power, the total number of nerves per field was quantified, then was averaged. The histologic characteristics of each clitoral component were described. Two investigators evaluated all specimens.

Main Outcome Measures: Descriptives of large (≥3 fibers) and small nerves based on location in the CUC.

Results: Nerve quantification revealed the glans to be the most populated by small nerves (52.1, standard deviation [SD] 26.2). As slices through each specimen moved caudad toward the urethra, the number of small nerves dramatically decreased from 40.4 (SD 10.8) in the body and 29.8 (SD 8.8) (superior CUC) near the bulb to 23.7 (SD 9.8) in the middle CUC and 20.5 (SD 10.4) (inferior CUC) near the urethra. Although the variation in small nerves was striking, large nerves were somewhat uniform and comprised a minority of the overall quantity. Neuroanatomy was consistent for all cadaver specimens.

Conclusions: Our study provided a description of the nerve distribution throughout the central CUC. Increased density of small nerves in the glans suggests this is the location of heightened sensation. Decreasing quantity of nerves in segments closer to the urethra may indicate these zones are less important for sexual sensation. Knowledge of human clitoral innervation is important for understanding the complexities of the female sexual response cycle.