The anatomy of the perineal body in relation to abdominoperineal excision for low rectal cancer

Abstract

Aim Dissection of the perineal body (PB) during abdominoperineal excision (APE) for low rectal cancer is often difficult due to the lack of a natural plane of dissection. Understanding the PB and its relation to the anorectum is essential to permit safe dissection during the perineal phase of the operation and avoid damage to the anorectum and urogenital organs. This study describes the anatomy and histology of the PB relevant to APE. Method Six human adult cadaver pelvic exenteration specimens (three male, three female) from the Leeds GIFT Research Tissue Programme were studied. Paraffin‐embedded mega‐blocks were produced and serially sectioned at 50‐ and 250‐μm intervals. Sections were stained by immunohistochemistry to show collagen, elastin and smooth muscle. Results The PB was cylindrically shaped in the male specimens and wedge‐shaped in the female ones. Although centrally located between the anal and urogenital triangles, it was nearly completely formed by muscle fibres derived from the rectal muscularis propria. Thick bundles of smooth muscle, mostly arising from the longitudinal muscle, inserted into the PB and levator ani muscle (LAM). The recto‐urethralis muscle originated from the PB and separated the anterolateral PB from the urogenital organs. Conclusion Smooth muscle fibres derived from the rectal muscularis propria extend into the PB and LAM and appear to fix the anorectum. Dissection of the PB during APE is safe only when the smooth muscle fibres that extend into the PB are divided.

Denonvilliers’ fascia in men: a sheet plastination and confocal microscopy study of the prerectal space and the presence of an optimal anterior plane when mobilizing the rectum for cancer

“…As demonstrated in this study (Fig. 3a), some superficial fibres from the longitudinal rectal muscle contribute to the perineal body as shown by others [34] and project longitudinally or transversely to become continuous with the adipose fibrous meshwork within the prerectal space. It is therefore entirely plausible that mechanical stresses caused by rectal mobilization contribute to different configurations seen in the prerectal space [11].…”

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

“…For example, stretching of the perineal body during pregnancy does not substantially impact defecatory, urinary or reproductive muscle function (Meriwether et al, ). Similarly, surgical dissection through the perineal body does not adversely affect the functions of superficial perineal muscles in either males or females (Kraima et al, ).…”

Perineorrhaphy Compared With Pelvic Floor Muscle Therapy in Women With Late Consequences of a Poorly Healed Second-Degree Perineal Tear

“…13 Thin-sliced magnetic resonance imaging (MRI) and cadaver dissection studies has shown that the bulbocavernosus muscle, the superficial and deep transverse perineal muscle, the internal and external anal sphincters as well as the puboperinealis and puboanalis portions of the puborectalis muscle all attach to the perineal body. [14][15][16] The bulbocavernosus muscles cover the superficial parts of the vestibular bulbs and the major vestibular glands. They consist of striated muscles 15,17 and run from the body of the clitoris, beneath the labia majora surrounding the vaginal orifice, inserting in the upper and lateral part of the perineal body.…”

“…[14][15][16] The bulbocavernosus muscles cover the superficial parts of the vestibular bulbs and the major vestibular glands. They consist of striated muscles 15,17 and run from the body of the clitoris, beneath the labia majora surrounding the vaginal orifice, inserting in the upper and lateral part of the perineal body. 18 By contracting they cause a narrowing of the vaginal orifice and by compressing the deep dorsal vein of the clitoris, they contribute to female erection.…”