Human anus
Encyclopedia
The human anus is the external opening of the rectum
. Like other animals, its closure is controlled by sphincter
muscle
s. Feces
are expelled from the body through the anus during the act of defecation
, the primary function of the anus.
The anus plays a role in sexuality, though attitudes towards anal sex
vary; it is illegal in some countries. The anus is also the site of potential infections and other conditions including cancer
. The subject is often considered a taboo
part of the body, and it is known by a large number of usually vulgar
slang
terms. The traditional polite synonym for anus was fundament, though this euphemism
is rarely heard now that medical terms are widely acceptable.
fills with feces, pushing the feces against the walls of the anal canal
. Contractions of abdominal and pelvic floor muscles can create intra-abdominal pressure which further increases intra-rectal pressure. The internal anal sphincter (an involuntary muscle) responds to the pressure by relaxing, thus allowing the feces to enter the canal. The rectum shortens as feces are pushed into the anal canal and peristaltic waves
push the feces out of the rectum. Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, as the levator ani
muscles pull the anus up over the exiting feces.
To prevent diseases of the anus and to promote general hygiene, humans often clean the exterior of the anus after emptying the bowels. A rinse with water from a bidet or a wipe with toilet paper
are often used for this purpose.
s and is an erogenous zone
, which can make anal intercourse pleasurable for both the insertive partner and the receptive partner. Sigmund Freud
's theory of psychosexual development
, for example, described an anal stage
, hypothesizing that toddlers derive pleasure from retaining and expelling feces. This is the source of the term "anal-retentive
" and the derived, derogatory vulgarism "anal".
In addition to nerve endings, pleasure from anal intercourse occurs due to the shared wall between the anus and the prostate
for males and vagina
/G-Spot
for females. This allows for indirect stimulation of the G-Spot or clitoral
legs in women and prostate in men. For a male insertive partner, the tightness of the anus can be a source of pleasure via the tactile pressure on the penis. The anus also plays an important role in anal masturbation
, fingering
, fisting
, facesitting
, anilingus, and a variety of other penetrative and non-penetrative acts. Anal stretching can stimulate the nerves around the anus and can be considered pleasurable. Care must be taken to maintain elasticity. Lubricant is widely regarded as a necessity while performing anal sex.
Anal intercourse is sometimes referred to as sodomy
or buggery
, and is considered taboo
in a number of legal systems. It has been, and in some jurisdiction
s continues to be, a crime carrying severe punishment.
, as testosterone triggers androgenic hair
growth on the body, pubic hair begins to appear around the anus. Although initially sparse, it fills out by the end of puberty, if not earlier. However, in some ethnicities, androgenic hair is less common.
s are sometimes the source of anal itching
.
Care should be taken not to strip the anus of natural oils that keep the skin around the opening supple and elastic.
Penetration with a penis or sex toy
can irritate or tear the inside of the anus. Lubrication is often recommended to ease penetration. The risk of injury to the anal sphincter should be a concern. Similarly if the anus is torn, this can occasionally cause a fistula
formation which can not only cause fecal leaking, but also can be very difficult to treat.
Sphincter exercise can improve the tone of the outer sphincter muscle.
(hair removal), or Brazilian waxing can clear the perineum
of hair.
Anal bleaching
is a process in which the anus and perineum, which may darken after puberty depending on individual genetics, is lightened for a more youthful appearance.
True anal piercing
is rare because it may interfere with the function of the anus. However, surface piercings of the perineum are easier to care for and much more common.
, abscess
, wart
s, fistula
, anal fissure
, itch
ing and hemorrhoid
. The anus is also a frequent site of sexually transmitted infections. These benefit from medical intervention.
Birth defects of the anus include stenosis
and imperforation
. These benefit from surgical intervention.
Damaged anal sphincter (patulous anus in more severe cases) — caused by careless or sometimes necessarily sacrificial surgery in the perineal
region or by rough/abrupt penetration in anal sex
— can lead to flatus and/or fecal incontinence
, chronic constipation
and, ultimately, megacolon
.
In psychology
the Freud
ian term anal fixation is used.
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
. Like other animals, its closure is controlled by 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...
muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s. Feces
Feces
Feces, faeces, or fæces is a waste product from an animal's digestive tract expelled through the anus or cloaca during defecation.-Etymology:...
are expelled from the body through the anus during the act of defecation
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...
, the primary function of the anus.
The anus plays a role in sexuality, though attitudes towards 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...
vary; it is illegal in some countries. The anus is also the site of potential infections and other conditions including 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...
. The subject is often considered a taboo
Taboo
A taboo is a strong social prohibition relating to any area of human activity or social custom that is sacred and or forbidden based on moral judgment, religious beliefs and or scientific consensus. Breaking the taboo is usually considered objectionable or abhorrent by society...
part of the body, and it is known by a large number of usually vulgar
VULGAR
Vulgar is the fourth studio album released by Dir En Grey on September 10, 2003 in Japan and on February 21, 2006 in Europe. A limited edition containing an additional DVD was also released. It featured the video of the song "Obscure", albeit a censored version...
slang
Slang
Slang is the use of informal words and expressions that are not considered standard in the speaker's language or dialect but are considered more acceptable when used socially. Slang is often to be found in areas of the lexicon that refer to things considered taboo...
terms. The traditional polite synonym for anus was fundament, though this euphemism
Euphemism
A euphemism is the substitution of a mild, inoffensive, relatively uncontroversial phrase for another more frank expression that might offend or otherwise suggest something unpleasant to the audience...
is rarely heard now that medical terms are widely acceptable.
Defecation
Intra-rectal pressure builds as the rectumRectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
fills with feces, pushing the feces against 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....
. Contractions of abdominal and pelvic floor muscles can create intra-abdominal pressure which further increases intra-rectal pressure. The internal anal sphincter (an involuntary muscle) responds to the pressure by relaxing, thus allowing the feces to enter the canal. The rectum shortens as feces are pushed into the anal canal and peristaltic waves
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...
push the feces out of the rectum. Relaxation of the internal and external anal sphincters allows the feces to exit from the anus, finally, as the levator ani
Levator ani
The 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 pull the anus up over the exiting feces.
To prevent diseases of the anus and to promote general hygiene, humans often clean the exterior of the anus after emptying the bowels. A rinse with water from a bidet or a wipe with toilet paper
Toilet paper
Toilet paper is a soft paper product used to maintain personal hygiene after human defecation or urination. However, it can also be used for other purposes such as blowing one's nose when one has a cold or absorbing common spills around the house, although paper towels are more used for the latter...
are often used for this purpose.
Sexuality
The anus has a relatively high concentration of nerve endingNerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
s and is an erogenous zone
Erogenous zone
An erogenous zone is an area of the human body that has heightened sensitivity, the stimulation of which may result in the production of erotic sensations or sexual excitement.People have erogenous zones all over their bodies, but which areas are more sensitive than others vary...
, which can make anal intercourse pleasurable for both the insertive partner and the receptive partner. Sigmund Freud
Sigmund Freud
Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...
's theory of psychosexual development
Psychosexual development
In Freudian psychology, psychosexual development is a central element of the psychoanalytic sexual drive theory, that human beings, from birth, possess an instinctual libido that develops in five stages. Each stage — the oral, the anal, the phallic, the latent, and the genital — is characterized...
, for example, described an anal stage
Anal stage
The anal stage, in Freudian psychology, is the period of human development occurring at about one to two years of age. Around this age, the child begins to toilet train, which brings about the child's fascination in the erogenous zone of the anus...
, hypothesizing that toddlers derive pleasure from retaining and expelling feces. This is the source of the term "anal-retentive
Anal retentive
The term anal-retentive , commonly abbreviated to anal, is used conversationally to describe a person who pays such attention to detail that the obsession becomes an annoyance to others, and can be carried out to the detriment of the anal-retentive person. The term derives from Freudian...
" and the derived, derogatory vulgarism "anal".
In addition to nerve endings, pleasure from anal intercourse occurs due to the shared wall between the anus and the prostate
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
for males and vagina
Vagina
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...
/G-Spot
G-spot
The Gräfenberg Spot, often called the G-Spot, is a bean-shaped area of the vagina. Many women report that it is an erogenous zone which, when stimulated, can lead to strong sexual arousal, powerful orgasms and female ejaculation...
for females. This allows for indirect stimulation of the G-Spot or clitoral
Clitoris
The clitoris is a sexual organ that is present only in female mammals. In humans, the visible button-like portion is located near the anterior junction of the labia minora, above the opening of the urethra and vagina. Unlike the penis, which is homologous to the clitoris, the clitoris does not...
legs in women and prostate in men. For a male insertive partner, the tightness of the anus can be a source of pleasure via the tactile pressure on the penis. The anus also plays an important role in anal masturbation
Anal masturbation
Anal masturbation is manual erotic stimulation focusing on the anus and rectum. For humans, common methods of anal masturbation include manual stimulation of the anal opening and the insertion of an object or objects such as fingers, feet, fists, phallic shaped items, water play, or sex toys such...
, fingering
Fingering (sexual act)
Fingering is the manual manipulation of the clitoris, vulva, vagina, or anus for the purpose of sexual arousal and stimulation. It may constitute the entire sexual encounter or it may be part of mutual masturbation, foreplay or other sexual activities. To "finger oneself" is to masturbate in this...
, fisting
Fisting
Fisting is a sexual activity that involves inserting a hand into the vagina or rectum. Once insertion is complete, the fingers either naturally clench into a fist or remain straight. In more vigorous forms of fisting, such as "punching", a fully clenched fist may be inserted and withdrawn slowly...
, facesitting
Facesitting
Facesitting, also known as queening, is a sexual practice in which one partner sit on or over the other's face, typically to allow or force oral-genital or oral-anal contact. It is common for this position to form part of BDSM, involving dominance and submission, though this need not be the case...
, anilingus, and a variety of other penetrative and non-penetrative acts. Anal stretching can stimulate the nerves around the anus and can be considered pleasurable. Care must be taken to maintain elasticity. Lubricant is widely regarded as a necessity while performing anal sex.
Anal intercourse is sometimes referred to as sodomy
Sodomy
Sodomy is an anal or other copulation-like act, especially between male persons or between a man and animal, and one who practices sodomy is a "sodomite"...
or buggery
Buggery
The British English term buggery is very close in meaning to the term sodomy, and is often used interchangeably in law and popular speech. It may be, also, a specific common law offence, encompassing both sodomy and bestiality.-In law:...
, and is considered taboo
Taboo
A taboo is a strong social prohibition relating to any area of human activity or social custom that is sacred and or forbidden based on moral judgment, religious beliefs and or scientific consensus. Breaking the taboo is usually considered objectionable or abhorrent by society...
in a number of legal systems. It has been, and in some jurisdiction
Jurisdiction
Jurisdiction is the practical authority granted to a formally constituted legal body or to a political leader to deal with and make pronouncements on legal matters and, by implication, to administer justice within a defined area of responsibility...
s continues to be, a crime carrying severe punishment.
Puberty
During pubertyPuberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
, as testosterone triggers androgenic hair
Androgenic hair
Androgenic hair, colloquially body hair, is the terminal hair that develops on the body during and after puberty. It is differentiated from the head hair and less visible vellus hair, which are much finer and lighter in color. The growth of androgenic hair is related to the level of androgens in...
growth on the body, pubic hair begins to appear around the anus. Although initially sparse, it fills out by the end of puberty, if not earlier. However, in some ethnicities, androgenic hair is less common.
Health
Hygiene is important for good anal health. Washing with a mild soap and water will keep the anus clean. Harsh soaps or wiping vigorously with toilet paper can irritate the skin around the anus, making it itchy or sore. PinwormPinworm
The pinworm , also known as threadworm or seatworm, is a nematode and a common human intestinal parasite, especially in children...
s are sometimes the source of anal itching
Pruritus ani
Pruritus ani is the irritation of the skin at the exit of the rectum, known as the anus, causing the desire to scratch. The intensity of anal itching increases from moisture, pressure, and rubbing caused by clothing and sitting...
.
Care should be taken not to strip the anus of natural oils that keep the skin around the opening supple and elastic.
Penetration with a penis or sex toy
Sex toy
A sex toy is an object or device that is primarily used to facilitate human sexual pleasure. The most popular sex toys are designed to resemble human genitals and may be vibrating or non-vibrating...
can irritate or tear the inside of the anus. Lubrication is often recommended to ease penetration. The risk of injury to the anal sphincter should be a concern. Similarly if the anus is torn, this can occasionally cause a fistula
Anal fistula
Anal fistula, or fistula-in-ano, is an abnormal connection between the epithelialised surface of the anal canal and the perianal skin....
formation which can not only cause fecal leaking, but also can be very difficult to treat.
Sphincter exercise can improve the tone of the outer sphincter muscle.
Cosmetics
Shaving, trimming, depilatoryHair removal
Hair removal is the removal of body hair, and describes the methods used to achieve that result.Hair typically grows all over the human body during and after puberty. Men tend to have more body hair than women. Both men and women tend to have hair on the head, eyebrows, eyelashes, armpits, pubic...
(hair removal), or Brazilian waxing can clear the perineum
Perineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
of hair.
Anal bleaching
Anal bleaching
Anal bleaching is the process of lightening the color of the skin around the anus. It is done for cosmetic purposes, to make the anus more uniform with the surrounding area....
is a process in which the anus and perineum, which may darken after puberty depending on individual genetics, is lightened for a more youthful appearance.
True anal piercing
Anal piercing
An anal piercing is a body piercing around the surrounding area of the anus.Anal piercings are not very common compared to many other body piercings...
is rare because it may interfere with the function of the anus. However, surface piercings of the perineum are easier to care for and much more common.
Pathology
Diseases of the anus include anal cancerAnal cancer
Anal cancer is a type of cancer which arises from the anus, the distal orifice of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer. The etiology, risk factors, clinical progression, staging, and treatment are all different. Anal cancer is typically a...
, abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
, wart
Wart
A wart is generally a small, rough growth, typically on a human’s hands or feet but often other locations, that can resemble a cauliflower or a solid blister. They are caused by a viral infection, specifically by human papillomavirus 2 and 7. There are as many as 10 varieties of warts, the most...
s, fistula
Anal fistula
Anal fistula, or fistula-in-ano, is an abnormal connection between the epithelialised surface of the anal canal and the perianal skin....
, anal fissure
Anal fissure
An anal fissure is a break or tear in the skin of the anal canal. Anal fissures may be noticed by bright red anal bleeding on the toilet paper, sometimes in the toilet. If acute they may cause severe periodic pain after defecation but with chronic fissures pain intensity is often less...
, itch
Itch
Itch is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to classify it as any one type of sensory experience. Modern science has shown that itch has many similarities to pain, and while both are unpleasant sensory experiences, their behavioral response...
ing and hemorrhoid
Hemorrhoid
Hemorrhoids or haemorrhoids , are vascular structures in the anal canal which help with stool control. They become pathological or piles when swollen or inflamed. In their physiological state they act as a cushion composed of arterio-venous channels and connective tissue that aid the passage of...
. The anus is also a frequent site of sexually transmitted infections. These benefit from medical intervention.
Birth defects of the anus include stenosis
Stenosis
A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
and imperforation
Imperforate anus
An imperforate anus or anal atresia is a birth defect in which the rectum is malformed. Its cause is unknown.-Features:There are several forms of imperforate anus:* A low lesion, in which the colon remains close to the skin...
. These benefit from surgical intervention.
Damaged anal sphincter (patulous anus in more severe cases) — caused by careless or sometimes necessarily sacrificial surgery in the perineal
Perineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
region or by rough/abrupt penetration in 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...
— can lead to flatus and/or fecal incontinence
Fecal incontinence
Fecal incontinence is the loss of regular control of the bowels. Involuntary excretion and leaking are common occurrences for those affected. Subjects relating to defecation are often socially unacceptable, thus those affected may be beset by feelings of shame and humiliation...
, chronic constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
and, ultimately, megacolon
Megacolon
Megacolon is an abnormal dilation of the colon . The dilatation is often accompanied by a paralysis of the peristaltic movements of the bowel...
.
In psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
the Freud
Sigmund Freud
Sigmund Freud , born Sigismund Schlomo Freud , was an Austrian neurologist who founded the discipline of psychoanalysis...
ian term anal fixation is used.
See also
- Anal stageAnal stageThe anal stage, in Freudian psychology, is the period of human development occurring at about one to two years of age. Around this age, the child begins to toilet train, which brings about the child's fascination in the erogenous zone of the anus...
(Freudian psychosexual stage) - Anococcygeal nerveAnococcygeal nerveThe anococcygeal nerve is a nerve in the pelvis which provides sensory innervation to the skin over the coccyx.-Structure:The anococcygeal nerve arises from a small plexus known as the coccygeal plexus...
- CloacaCloacaIn zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...
- CoccydyniaCoccydyniaCoccydynia is a medical term meaning pain in the coccyx or tailbone area, usually brought on by sitting too abruptly.-Diagnosis:A number of different conditions can cause pain in the general area of the coccyx, but not all involve the coccyx and the muscles attached to it. The first task of...
- CoccyxCoccyxThe coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between...
- Digestive system
- FlatulenceFlatulenceFlatulence is the expulsion through the rectum of a mixture of gases that are byproducts of the digestion process of mammals and other animals. The medical term for the mixture of gases is flatus, informally known as a fart, or simply gas...
- HemorrhoidHemorrhoidHemorrhoids or haemorrhoids , are vascular structures in the anal canal which help with stool control. They become pathological or piles when swollen or inflamed. In their physiological state they act as a cushion composed of arterio-venous channels and connective tissue that aid the passage of...