A sphincter is a circular muscle that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning. The rectum is the concluding part of the large intestine that terminates in the anus. The average length of the human rectum may range between 10 and 15 cm. Its diameter can be compared to that of the sigmoid colon (the part of the large intestine nearest the rectum) at its onset. Combine these and you get Rincter.
by Rincter May 1, 2020