Rectum
The posterior aspect of the rectum exposed by removing the lower part of the sacrum and the coccyx.
The
Rectum is the final portion of the large intestine in some
mammals, and the gut in others, terminating in the
anus.
Medical procedures
For the diagnosis of certain ailments, a rectal exam may be done.
Suppositories may be inserted into the rectum as a
route of administration for
medicine.
Electroejaculation may be conducted for the treatment of anejaculation and ejaculatory dysfunction in men.
Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a mercury thermometer for 2-3 minutes, or a digital
thermometer until it "beeps", not more than an 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 97.6 degrees Fahrenheit to 100.4 degrees Fahrenheit and is roughly one degree above oral (mouth) temperature and roughly two degrees above axillary (armpit) temperature. On average, the rectal temperature is 0.7 degrees higher than oral temperature. Many
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.
Anatomy of the anus and rectum
The rectum in human defecation
The rectum ampulla 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 defecate. If the urge is not acted upon, the material in the rectum is often returned to the
colon where more water is absorbed. If defecation is delayed for a prolonged period
constipation and hardened feces results.
When the rectum is 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 peristaltic waves propel the feces out of the rectum. The internal and external
sphincter allow the feces to be passed by muscles pulling the anus up over the exiting feces.
See
defecation for a fuller treatment.
Muscular anatomy of the human pelvis and rectum
The Levatores ani constrict the lower end of the rectum and vagina. They elevate and invert the lower end of the rectum after it has been protruded and everted during the expulsion of the feces. They are also muscles of forced expiration. The Coccygei pull forward and support the
coccyx, after it has been pressed backward during defecation or parturition. The Levatores ani and Coccygei together form a muscular diaphragm which supports the pelvic viscera.
Sexual stimuli
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 can result in
sexual arousal. As a
human sexual behavior, often this takes the form of
anal intercourse or penetration with specialised anal
sex toys such as
butt plugs.
See also
Category:Digestive system
da:Rectum
de:Mastdarm
nl:Endeldarm
es:recto