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The rectum receives fecal material from the descending colon, transmitted through regular muscle contractions called peristalsis. [11] As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous system located in the rectal walls stimulate the desire to pass feces, a process called defecation. [11]
In humans, the anal canal is approximately 2.5 to 4 cm (0.98 to 1.57 in) long, from the anorectal junction to the anus. [2] [3] [4] It is directed downwards and backwards.. It is surrounded by inner involuntary and outer voluntary sphincters which keep the lumen closed in the form of an anteroposterior sl
It is an important anatomical landmark in humans, and forms the boundary between the anal canal and the rectum according to the anatomic definition. [1] Colorectal surgeons instead define the anal canal as the zone from the anal verge to the anorectal ring (palpable structure formed by the external anal sphincter and the puborectalis muscle ...
In humans, the anus (pl.: anuses or ani; from Latin ānus, "ring", "circle") [1] [2] is the external opening of the rectum located inside the intergluteal cleft.Two sphincters control the exit of feces from the body during an act of defecation, which is the primary function of the anus.
One is situated near the commencement of the rectum, on the right side. A second extends inward from the left side of the tube, opposite the middle of the sacrum. A third, the largest and most constant, projects backward from the forepart of the rectum, opposite the fundus of the urinary bladder.
Anatomy photo:43:11-0107 at the SUNY Downstate Medical Center — "The Female Pelvis: The Rectum" This page was last edited on 26 January 2025, at 13:24 (UTC). ...
The final branch which is important for the digestive system is the inferior mesenteric artery, which supplies the regions of the digestive tract derived from the hindgut, which includes the distal 1/3 of the transverse colon, descending colon, sigmoid colon, rectum, and the anus above the pectinate line.
The internal anal sphincter, IAS, or sphincter ani internus is a ring of smooth muscle that surrounds about 2.5–4.0 cm of the anal canal.It is about 5 mm thick, and is formed by an aggregation of the smooth (involuntary) circular muscle fibers of the rectum.