A functional and clinical reinterpretation of human perineal neuromuscular anatomy: Application to sexual function and continence

Abstract

Modern anatomical and surgical references illustrate perineal muscles all innervated by branches of the pudendal nerve but still organized into anatomically distinct urogenital and anal triangles with muscles inserting onto a central perineal body. However, these conflict with the anatomy commonly encountered during dissection. We used dissections of 43 human cadavers to characterize the anatomical organization of the human perineum and compare our findings to standard references. We found bulbospongiosus and the superficial portion of the external anal sphincter (EAS) were continuous anatomically with a common innervation in 92.3% of specimens. The superficial transverse perineal muscle inserted anterior and lateral to the midline, interdigitating with bulbospongiosus. The three EAS subdivisions were anatomically discontinuous. Additionally, in 89.2% of our sample the inferior rectal nerve emerged as a branch of S3 and S4 distinct from the pudendal nerve and innervated only the subcutaneous EAS. Branches of the perineal nerve innervated bulbospongiosus and the superficial EAS and nerve to levator ani innervated the deep EAS. In conclusion, we empirically demonstrate important and clinically relevant differences with perineal anatomy commonly described in standard texts. First, independent innervation to the three portions of EAS suggests the potential for functional independence. Second, neuromuscular continuity between bulbospongiosus and superficial EAS suggests the possibility of shared or overlapping function of the urogenital and anal triangles. Clin. Anat. 29:1053-1058, 2016. © 2016 Wiley Periodicals, Inc.

Spatial distribution of smooth muscle tissue in the male pelvic floor with special reference to the lateral extent of the rectourethralis muscle: Application to prostatectomy and proctectomy

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The anatomy of transanal minimally invasive surgery: Perineal distances and transanal angles

“…Damage to the superior hypogastric nerve trunks during mesorectal mobilization can lead to urinary incontinence and retrograde ejaculation. Traditionally, supply to the perineal muscles is described as being via branches of the pudendal nerve; however, a recent study by Piochocki et al () has described the inferior rectal nerve emerging from a branch of S3–S4 distinct from the pudendal nerve, and Barber et al () have described a nerve to levator ani originating directly from nerve roots S3–S5 ii also provides innervation to the deep part of the external anal sphincter. Additional structures at risk anteriorly are the vagina in women, and prostate and urethra in men.…”

The clinical anatomy of dyspareunia: A review

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