Rectum
Encyclopedia
- "Rectal" redirects here. For the route of administration, see Rectal (medicine)Rectal (medicine)The rectal route of administration is a way of administering drugs into the rectum to be absorbed by the rectum's blood vesselsThe rectum has numerous amounts of blood vessels available to absorbed the drug introduced into the rectum...
. - For the conic sections see Latus rectum or Semi-latus rectum
The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
in some mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, and the gut
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
in others, terminating in the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
. The human rectum is about 12 cm long. Its caliber is similar to that of the sigmoid colon
Sigmoid colon
The sigmoid colon is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm...
at its commencement, but it is dilated near its termination, forming the rectal ampulla
Rectal ampulla
The rectal ampulla is the dilated section of the rectum where feces are stored until they are eliminated via the anal canal. The caliber of the rectum at its commencement is similar to that of the sigmoid colon, but near its termination it dilates, forming the ampulla....
.
Role in human defecation
The rectum intestinum acts as a temporary storage site for feces. As the rectal walls expand due to the materials filling it from within, stretch receptors from the nervous systemNervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
located in the rectal walls stimulate the desire to defecate
Defecation
Defecation is the final act of digestion by which organisms eliminate solid, semisolid or liquid waste material from the digestive tract via the anus. Waves of muscular contraction known as peristalsis in the walls of the colon move fecal matter through the digestive tract towards the rectum...
. If the urge is not acted upon, the material in the rectum is often returned to the colon
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
where more water is absorbed. If defecation is delayed for a prolonged period, constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
and hardened feces results.
When the rectum becomes full, the increase in intrarectal pressure forces the walls of the anal canal
Anal canal
The anal canal is the terminal part of the large intestine.It is situated between the rectum and anus, below the level of the pelvic diaphragm. It lies in the anal triangle of perineum in between the right and left ischioanal fossa....
apart, allowing the fecal matter to enter the canal. The rectum shortens as material is forced into the anal canal and peristaltic wave
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
s propel the feces out of the rectum. The internal and external sphincter
Sphincter
A sphincter is an anatomical structure, or a circular muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological functioning...
allow the feces to be passed by muscles pulling the anus up over the exiting feces.
Supports of rectum
- Pelvic floor formed by levator aniLevator aniThe levator ani is a broad, thin muscle, situated on the side of the pelvis.It is attached to the inner surface of the side of the lesser pelvis, and unites with its fellow of the opposite side to form the greater part of the floor of the pelvic cavity....
muscles. - Fascia of Waldeyer
- Lateral ligaments of rectum which are formed by the condensation of pelvic fascia
- Rectovesical fascia of Denonvillers, which extends from rectum behind to the seminal vesicles and prostate in front.
- Pelvic peritoneum
- Perineal bodyPerineal bodyThe perineal body is a pyramidal fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle . It is found in both males and females...
Medical procedures
For the diagnosis of certain ailments, a rectal exam may be done.Suppositories
Suppository
A suppository is a drug delivery system that is inserted into the rectum , vagina or urethra , where it dissolves.They are used to deliver both systemically-acting and locally-acting medications....
may be inserted into the rectum as a route of administration
Route of administration
A route of administration in pharmacology and toxicology is the path by which a drug, fluid, poison, or other substance is taken into the body.-Classification:Routes of administration are usually classified by application location...
for medicine.
The endoscopic
Endoscopy
Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
procedures colonoscopy
Colonoscopy
Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
and sigmoidoscopy
Sigmoidoscopy
Sigmoidoscopy From Greek Sigma - eidos - scopy, to look inside an s-like object, is the minimally invasive medical examination of the large intestine from the rectum through the last part of the colon. There are two types of sigmoidoscopy, flexible sigmoidoscopy, which uses a flexible endoscope,...
are performed to diagnose diseases such as cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
.
Digital Rectal Stimulation, the insertion of one finger into the rectum, is used to induce peristalsis in patients whose own peristaltic reflex is inadequate to fully empty the rectum.
Manual Evacuation is the use of a gloved finger to evacuate faeces from the rectum, and is utilised primarily in acute constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
and also the long-term management of neurogenic bowel, seen most frequently in people with a spinal cord injury
Spinal cord injury
A spinal cord injury refers to any injury to the spinal cord that is caused by trauma instead of disease. Depending on where the spinal cord and nerve roots are damaged, the symptoms can vary widely, from pain to paralysis to incontinence...
or multiple sclerosis
Multiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
.
Temperature taking
related article: rectal thermometryRectal thermometry
Rectal thermometry is an umbrella term covering the practice, widely used in modern medicine and science, of taking a mammal's temperature by inserting a thermometer into the aforementioned mammal's rectum via the anus. This is generally regarded as the most accurate means of temperature-taking,...
Body temperature can also be taken in the rectum. Rectal temperature can be taken by inserting a medical thermometer
Medical thermometer
Medical thermometers are used for measuring human body temperature, with the tip of the thermometer being inserted either into the mouth under the tongue , under the armpit , or into the rectum via the anus .-Liquid-filled:The traditional thermometer is a glass tube with a bulb at one end...
not more than 25 mm (1 inch) into the rectum via the anus
Anus
The anus is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, unwanted semi-solid matter produced during digestion, which, depending on the type of animal, may be one or more of: matter which the animal cannot digest,...
. A mercury thermometer
Mercury-in-glass thermometer
A mercury-in-glass thermometer, also known as a mercury thermometer, was invented by German physicist Daniel Gabriel Fahrenheit in 1724 and is a thermometer consisting of mercury in a glass tube. Calibrated marks on the tube allow the temperature to be read by the length of the mercury within the...
should be inserted for 3 to 5 minutes; a digital thermometer should remain inserted until it beeps. Due to recent concerns related to mercury poisoning
Mercury poisoning
Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses...
, the use of mercury thermometers is outlawed. 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 axilla
Axillary
Axillary means "related to the axilla "."Axillary" may refer to:* Axillary artery* Axillary vein* Axillary nerve* Axillary bud...
(armpit) temperature.
Pediatricians
Pediatrics
Pediatrics or paediatrics is the branch of medicine that deals with the medical care of infants, children, and adolescents. A medical practitioner who specializes in this area is known as a pediatrician or paediatrician...
recommend that parents take infant
Infant
A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...
s' and toddler
Toddler
A toddler is a young child, usually defined as being between the ages of one and three. Registered nurse, midwife and author, Robin Barker, states 'Any time from eight months onwards your baby will begin to realise he is a separate person from you...
s' temperature in the rectum for two reasons:
- Rectal temperature is the closest to core body temperature and in young children, accuracy is critical.
- Younger children are unable to cooperate when having their temperature taken by mouth (oral), which is recommended for children ages 6 and above as well as adults.
In recent years, the introduction of tympanic (ear) thermometers and changing attitudes on privacy
Privacy
Privacy is the ability of an individual or group to seclude themselves or information about themselves and thereby reveal themselves selectively...
and modesty
Modesty
Standards of modesty are aspects of the culture of a country or people, at a given point in time, and is a measure against which an individual in society may be judged....
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 vaginaVagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
in females or to the prostate
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
in males and the shared nerves thereof, rectal stimulation
Stimulation
Stimulation is the action of various agents on nerves, muscles, or a sensory end organ, by which activity is evoked; especially, the nervous impulse produced by various agents on nerves, or a sensory end organ, by which the part connected with the nerve is thrown into a state of activity.The word...
or penetration can result in sexual arousal
Sexual arousal
Sexual arousal, or sexual excitement, is the arousal of sexual desire, during or in anticipation of sexual activity. Things that precipitate human sexual arousal are called erotic stimuli, or colloquially known as turn-ons. There are many potential stimuli, both physical or mental, which can cause...
. For further information on this aspect, see anal sex
Anal sex
Anal sex is the sex act in which the penis is inserted into the anus of a sexual partner. The term can also include other sexual acts involving the anus, including pegging, anilingus , fingering, and object insertion.Common misconception describes anal sex as practiced almost exclusively by gay men...
.
Additional images
See also
- Gastrointestinal tractGastrointestinal tractThe human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
- Murphy dripMurphy dripA Murphy drip is a rectal infusion apparatus to administer the medical procedure of proctoclysis, also known as rectoclysis. During the procedure, an end of the Murphy drip is inserted into the rectum and large quantities of liquid are infused into the rectum drop-by-drop...
- Pectinate linePectinate lineThe pectinate line is a line which divides the upper 2/3s and lower 1/3 of the anal canal. Developmentally, this line represents the hindgut-proctodeum junction....
- Rectal prolapseRectal prolapseRectal prolapse normally describes a medical condition wherein the walls of the rectum protrude through the anus and hence become visible outside the body.-Types:There are three chief conditions which come under the title rectal prolapse:...