The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straightportion of the large intestine in some mammals, and the gut in others. The human rectum is about 12 centimetres (4.7 in) long,[2] and begins at the rectosigmoid unction (the end of the sigmoid colon), at the le!el of the third sacral !ertebra or the sacral promontor" depending upon #hat definition is used.[$] %ts caliber is similar to that of the sigmoid colon at its commencement, but it is dilated near its termination, forming the rectal ampulla. %t terminatesat the le!el of the anorectal ring (the le!el of the puborectalis sling) or the dentate line, again depending upon #hich definition is used.[$] %n humans, the rectum is follo#ed b" the anal canal, before the gastrointestinal tract terminates at the anal !erge.Contents 1 &tructure 2 'unction $ (linical significance o $.1 )*aminationo $.2 +oute of administrationo $.$ (onstipationo $.4 ,ther disease 4 &ociet" and culture o 4.1 &e*ual stimulation - .istor" o -.1 )t"molog" / 0dditional images 7 &ee also 1 +eferences 2 )*ternal lin3sStructureThe rectum is a component of the lo#er gastrointestinal tract. The rectum is a continuation of the sigmoid colon, and connects to the anus. The rectum follo#s the shape of the sacrum, andends in an e*panded section called the rectal ampulla. 4nli3e other portions of the colon, the rectum does not ha!e taeniae coli.[4] 5$27The rectum connects #ith the sigmoid colon at the le!el of &$, and connects #ith the anal canal as it passes through the pel!ic floor muscles.[4] 5$27&upports of the rectum include5[citation needed] 6el!ic floor formed b" le!ator ani muscles. 7alde"er8s fascia Lateral ligaments of rectum #hich are formed b" the condensation of pel!ic fascia +ecto!esical fascia of 9enon!illers, #hich e*tends from rectum behind to the seminal!esicles and prostate in front. 6el!ic peritoneum 6erineal bod"FunctionThe rectum acts as a temporar" storage site for feces. 0s the rectal #alls e*pand due to the materials filling it from #ithin, stretch receptors from the ner!ous s"stem located in the rectal#alls stimulate the desire to defecate. %f the urge is not acted upon, the material in the rectum is often returned to the colon #here more #ater is absorbed from the feces. %f defecation is dela"ed for a prolonged period, constipation and hardened feces results.[citation needed]7hen the rectum becomes full, the increase in intrarectal pressure forces the #alls of the analcanal apart, allo#ing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic #a!es propel the feces out of the rectum. The internal and e*ternal sphincter allo# the feces to be passed b" muscles pulling the anus up o!er the e*iting feces.Clinical significanceExamination:ain article5 +ectal e*am'or the diagnosis of certain ailments, a rectal e*am ma" be done. These include faecal impaction, prostatic cancer and benign prostatic h"pertroph" in men, faecal incontinence, andinternal haemorrhoids.[-] 5172;11