Search results
Results From The WOW.Com Content Network
The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 35–40 centimetres (14–16 in) in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus sigma + -oid).
The rectum follows the shape of the sacrum and ends in an expanded section called an ampulla where feces is stored before its release via the anal canal. An ampulla (from Latin bottle ) is a cavity, or the dilated end of a duct, shaped like a Roman ampulla . [ 5 ]
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name sigmoid means S-shaped (see sigmoid; cf. sigmoid sinus). The walls of the sigmoid colon are muscular and contract to increase the pressure inside the colon, causing the stool to move into the rectum.
The anus is the site of potential infections and other conditions, including cancer (see anal cancer). [4] With anal sex, the anus can play a role in sexuality. Attitudes toward anal sex vary, and it is illegal in some countries. [5] The anus is often considered a taboo part of the body, [5] and is known by many, usually vulgar, slang terms.
A rectal prolapse occurs when walls of the rectum have prolapsed to such a degree that they protrude out of the anus and are visible outside the body. [2] However, most researchers agree that there are 3 to 5 different types of rectal prolapse, depending on whether the prolapsed section is visible externally, and whether the full or only partial thickness of the rectal wall is involved.
Sigmoidoscopy ("sigma", the Greek term for letter "s/ς" + "eidos" + "scopy": namely, to look inside an "s"/"ς"-like object) is the minimally invasive medical examination of the large intestine from the rectum through to the nearest part of the colon, the sigmoid colon.
During defecation patients may need to support the perineum on both sides, or evacuate fecal pellets from the rectum with a finger. There may be post defecation incontinence. These rectal wall abnormalities may be an important missed cause of obstructed defecation. S-shaped rectum and corkscrew rectum are both treated in the same way.
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