![]() ![]() The lymphatic drainage of the upper anal canal and internal anal sphincter drain upwards into the submucosal and intramural lymphatics of the rectum that then drain to perirectal nodes of the mesorectum and ultimately to the inferior mesenteric nodes. Above the dentate line, via the terminal branches of the superior rectal vein into the inferior mesenteric vein and portal system, and below the dentate line via the inferior rectal vein into the pudendal vein passing to the internal iliac vein. The venous drainage of the anal canal is divided into two patterns. The arterial supply of the anus is derived from branches of the superior rectal artery, the inferior rectal branch of the pudendal artery, and branches of the median sacral artery. The dentate line, identified by the termination of the anal columns, lies 1 to 2 cm above the anal verge. The upper anal canal is lined by columnar tissue that transitions into squamous epithelium at the dentate line. The anal verge can be identified visually as the part of the anal canal remaining closed when the buttocks are gently retracted. Outside of the anal verge lies the anal margin, also referred to as the perianal skin, which commonly encompasses a radius of 5 cm. The anal canal is defined as the caudal part of the large intestine extending from the anorectal ring to the anal verge and is ~3 to 5 cm in length.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |