View source for Rectum

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==Overview==
{{Infobox Anatomy |
  Name         = {{PAGENAME}} |
  Latin        = |
  GraySubject  = 249 |
  GrayPage     = 1183 |
  Image        = Anorectum.gif |
  Caption      = Anatomy of the anus and rectum |
  Image2       = Gray1077.png |
  Caption2     = The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx. |
  Precursor    = [[Hindgut]] |
  System       = |
  Artery       = [[middle rectal artery]], [[inferior rectal artery]]  |
  Vein         = [[middle rectal veins]], [[inferior rectal veins]]  |
  Nerve        = [[inferior anal nerves]], [[inferior mesenteric ganglia]]<ref>{{GeorgiaPhysiology|6/6ch2/s6ch2_30}}</ref> |
  Lymph        = [[internal iliac lymph nodes]] |
  MeshName     = Rectum |
  MeshNumber   = A03.556.124.526.767 |
  DorlandsPre  = r_05 |
  DorlandsSuf  = 12697487  |
}} 	
{{SI}}
The '''rectum''' (from the Latin ''rectum intestinum'', meaning ''straight intestine'') is the final [[straight]] portion of the [[large intestine]] in some [[mammal]]s, and the [[Gastrointestinal tract|gut]] in others, terminating in the [[anus]]. The human rectum is about 12 cm long. At its commencement its caliber is similar to that of the [[sigmoid colon]], but near its termination it is dilated, forming the [[rectal ampulla]].

== Role in human defecation ==

The [[rectum intestinum]] acts as a temporary storage facility for feces. 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 [[defecation|defecate]]. If the urge is not acted upon, the material in the rectum is often returned to the [[Colon (anatomy)|colon]] where more water is absorbed. If defecation is delayed for a prolonged period, [[constipation]] and hardened feces results.

When the rectum becomes full the increase in intrarectal pressure forces the walls of the [[anal canal]] apart allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and [[peristalsis|peristaltic wave]]s propel the feces out of the rectum. The internal and external [[sphincter]] allow the faeces to be passed by muscles pulling the anus up over the exiting faeces.

==Medical procedures==
For the diagnosis of certain [[ailment]]s, a [[rectal exam]] may be done. 

[[Suppository|Suppositories]] may be inserted into the rectum as a [[route of administration]] for [[medicine]]. 

The [[endoscopy|endoscopic]] procedures [[colonoscopy]] and [[sigmoidoscopy]] are performed to diagnose diseases such as [[cancer]]. 

===Temperature taking===
[[Body temperature]] can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 3 to 5 minutes, or a digital [[thermometer]] until it "beeps", not more than 25 mm (1 inch) into the rectum via the [[anus]]. Due to recent concerns related to [[mercury poisoning]], the use of mercury thermometers is now discouraged. Normal rectal temperature generally ranges from 36 to 38 °C (97.6 to 100.4 °F) and is about 0.5 °C (1 °F) above oral (mouth) temperature and about 1 °C (2 °F) above [[axillary]] ([[armpit]]) temperature.

Many [[pediatrics|pediatricians]] recommend that parents take [[infants]] and [[toddler]]'s temperature in the rectum for two reasons: 
* (1) Rectal temperature is the closest to core body temperature and in children that young, accuracy is critical. 
* (2) Younger children are unable to cooperate when having their temperature taken by mouth (oral) which is recommended for children, ages 6 and above and for adults. 

In recent years, the introduction of ear (tympanic) thermometers and changing attitudes on privacy and modesty have led some parents and doctors to discontinue taking rectal temperatures.

== Sexual stimulation ==
Due to the proximity of the anterior wall of the rectum to the [[vagina]] in females or to the [[prostate]] in males and the shared nerves thereof, rectal stimulation or penetration can result in [[sexual arousal]]. For further information on this aspect, see [[anal sex]].

==Additional images==
<gallery>
 Image:Illu repdt female.jpg|Organs of the [[Sex organ|female reproductive system]].
 Image:Gray403.png|Median sagittal section of pelvis, showing arrangement of fasciæ.
 Image:Gray539.png|The arteries of the pelvis.
 Image:Gray1082.png|Section of [[mucous membrane]] of human rectum. X 60.
 Image:Gray1083.png|The [[blood vessel]]s of the rectum and anus. 
 Image:Gray1228.png|Median sagittal section of male pelvis.
 Image:Gray1230.png|Median sagittal section of female pelvis.
 Image:WeiblichesBeckenMedian.gif|Sagittal section of the lower part of a female trunk, right segment.
 Image:Penis.svg|The rectum can be seen the left of this illustration. 
 Image:Rectum.JPG|Cross section microscopic shot of the rectal wall.
</gallery>

==See also== 
* [[Gastrointestinal tract]]
* [[Rectal prolapse]]
* [[Latus rectum]] (conic section)
* [[Ellipse#Semi-latus rectum and polar coordinates|Semi-latus rectum]]
* [[pectinate line]]

==References==
<references/>

==External links==
* {{ViennaCrossSection|pembody/body15a}}
* {{ViennaCrossSection|pelvis/pelvis-e12-15}}
* {{SUNYAnatomyImage|7|8|08}}
* {{SUNYAnatomyLabs|43|11|01|01}} - "The Female Pelvis: The Rectum"
* [http://www.kmle.com/search.php?Search=rectum KMLE Medical Dictionary definition of rectum] retrieved from [http://www.kmle.com KMLE Medical Dictionary] on 2007-03-25


{{digestive_system}}
{{human anatomical features}}

[[Category:Digestive system]]
[[Category:Pelvis]]

[[ar:مستقيم]]
[[cs:Konečník]]
[[da:Endetarm]]
[[de:Mastdarm]]
[[es:Recto]]
[[eo:Rektumo]]
[[fr:Rectum]]
[[io:Rektumo]]
[[id:Rektum]]
[[it:Retto]]
[[he:חלחולת]]
[[lt:Tiesioji žarna]]
[[nl:Endeldarm]]
[[ja:直腸]]
[[no:Endetarmen]]
[[pl:Odbytnica]]
[[pt:Recto]]
[[ro:Rect]]
[[ru:Прямая кишка человека]]
[[simple:Rectum]]
[[sk:Konečník]]
[[fi:Peräsuoli]]
[[sv:Ändtarm]]
[[zh:直肠]]

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