Essential Anatomy of the Anorectum for Colorectal Surgeons Focused on the Gross Anatomy and Histologic Findings

Abstract

The anorectum is a region with a very complex structure, and surgery for benign or malignant disease of the anorectum is impossible without accurate anatomical knowledge. The conjoined longitudinal muscle consists of smooth muscle from the longitudinal muscle of the rectum and the striate muscle from the levator ani and helps maintain continence; the rectourethralis muscle is connected directly to the conjoined longitudinal muscle at the top of the external anal sphincter. Preserving the rectourethralis muscle without damage to the carvernous nerve or veins passing through it when the abdominoperineal resection is implemented is important. The mesorectal fascia is a multi-layered membrane that surrounds the mesorectum. Because the autonomic nerves also pass between the mesorectal fascia and the parietal fascia, a sharp pelvic dissection must be made along the anatomic fascial plane. With the development of pelvic structure anatomy, we can understand better how we can remove the tumor and the surrounding metastatic lymph nodes without damaging the neural structure. However, because the anorectal anatomy is not yet fully understood, we hope that additional studies of anatomy will enable anorectal surgery to be performed based on complete anatomical knowledge.

High Prevalence of Slow Transit Constipation in Patients With Gastroparesis

“…Sacral nerve roots provide much of the extrinsic innervation to the pelvic floor and distal colon, and the pelvic floor contains a high degree of skeletal muscle under voluntary control. 27 In contrast, the extrinsic innervation to the rest of the GI tract and colon is largely from the autonomic nervous system via the vagus and thoracolumbar nerves. 17,18 This may fit with the argument of a strong central/learned component to dyssynergic defecation, 28 as opposed to underlying disordered motility.…”

The Five Diaphragms in Osteopathic Manipulative Medicine: Myofascial Relationships, Part 1

“…The endopelvic fascia covers the muscles that form the pelvic floor (levator ani and the ischiococcygeus muscle), the internal obturator and the piriformis muscle; finally, it merges with the presacral and periosteal fascia of the pubic area [42]. In the path of the endopelvic fascia, we find other small portions of connective tissue such as the Denonvilliers fascia (between the rectum and the seminal vesicles in men or between the rectum and vagina in women or the rectogenital fascia), the Walderyer fascia (between the posterior portion of the rectum at the caudal level of the sacrum and the presacral fascia or rectosacral fascia) [43]. The transversalis fascia comes into contact with the Gerota fascia or renal fascia, which covers the kidneys and adrenal glands; the transversalis fascia comes into contact with the Toldt fascia (fascia that covers the Gerota fascia anteriorly), which expands to involve many abdominal and pelvic viscera, to merge with the endopelvic fascia and the Fredet fascia (between the pancreatic-duodenal visceral peritoneum and the ascending mesocolon) [44].…”

Large intestine embryogenesis: Molecular pathways and related disorders (Review)

“…The transverse colon and sigmoid colon maintain a mobile mesentery, whereas the descending colon becomes immobile as its mesentery fixes to the dorsal wall. As regards the rectum, the upper third is intraperitoneal, the middle third retroperitoneal, whereas the lower third is infraperitoneal along with the superior anus (8).…”