Prostate massage Male genital anatomy, showing the location of the prostate with respect to the rectum The abundance of nerve endings in the anal region and rectum can make anal sex pleasurable for men or women. An Encyclopedia states that "the inner third of the anal canal is less sensitive to touch than the outer two-thirds, but is more sensitive to pressure" and that "the rectum is a curved tube about eight or nine inches long and has the capacity, like the anus, to expand".
With its glans or body as a whole estimated to have around 8, sensory nerve endings,   the clitoris surrounds the vagina and urethra ,  and may have a similar connection with the anus. In pornography, anal sex is commonly portrayed as a desirable, painless routine that does not require personal lubricant ; this can result in couples performing anal sex without care, and men and women believing that it is unusual for women, as receptive partners, to find discomfort or pain instead of pleasure from the activity.
Researchers say adequate application of a personal lubricant, relaxation, and communication between sexual partners are crucial to avoid pain or damage to the anus or rectum. The review suggests that anal sex is exotic among the sexual practices of some heterosexuals and that "for a certain number of heterosexuals, anal intercourse is pleasurable, exciting, and perhaps considered more intimate than vaginal sex". Because of this, some couples practice anal intercourse as a form of contraception , often in the absence of a condom.
This is sometimes termed technical virginity. Carpenter stated that this view "dates to the late s, with explicit 'rules' appearing around the turn of the twentieth century, as in marriage manuals defining petting as 'literally every caress known to married couples but does not include complete sexual intercourse.
McBride's clinical review on heterosexual anal intercourse and other forms of anal sexual activity, it is suggested that changing norms may affect the frequency of heterosexual anal sex.
As a result, we do not know the extent to which anal intercourse differs qualitatively from coitus. Women engaged in anal intercourse less commonly than men. This may be because of the taboo nature of anal sex and that teenagers and caregivers subsequently avoid talking to one another about the topic.
It is also common for subject review panels and schools to avoid the subject. A study found that They used condoms during anal sex However, many gay men and men who have sex with men in general those who identify as gay, bisexual , heterosexual or have not identified their sexual identity do not engage in anal sex.
Those who enjoy either role may be referred to as versatile. There are little published data on how many heterosexual men would like their anus to be sexually stimulated in a heterosexual relationship. Anecdotally, it is a substantial number. What data we do have almost all relate to penetrative sexual acts, and the superficial contact of the anal ring with fingers or the tongue is even less well documented but may be assumed to be a common sexual activity for men of all sexual orientations.
In , a non-scientific study Munson was conducted of more than members of a lesbian social organization in Colorado. When asked what techniques they used in their last ten sexual encounters, lesbians in their 30s were twice as likely as other age groups to engage in anal stimulation with a finger or dildo. Because of the view that anal sex is not "real sex" and therefore does not result in virginity loss, or pregnancy, teenagers and other young people may consider vaginal intercourse riskier than anal intercourse and believe that a STI can only result from vaginal intercourse.
For example, besides the risk of HIV transmission being higher for anal intercourse than for vaginal intercourse,    the risk of injury to the woman during anal intercourse is significantly higher than the risk of injury to her during vaginal intercourse because of the durability of the vaginal tissues compared to the anal tissues.
Research has found that psychological factors can in fact be the primary contributors to the experience of pain during anal intercourse and that adequate communication between sexual partners can prevent it, countering the notion that pain is always inevitable during anal sex. In some people, ASA may cause autoimmune infertility. Anal sex alone does not cause anal cancer; the risk of anal cancer through anal sex is attributed to HPV infection, which is often contracted through unprotected anal sex.
Because of this, men who have sex with men have a high risk of this cancer. Greek artwork of sexual interaction between men and boys usually depicted fondling or intercrural sex , which was not condemned for violating or feminizing boys,  while male-male anal intercourse was usually depicted between males of the same age-group.
Seducing those not of proper age for example, non-adolescent children into the practice was considered very shameful for the adult, and having such relations with a male who was no longer adolescent was considered more shameful for the young male than for the one mounting him; Greek courtesans, or hetaerae , are said to have frequently practiced male-female anal intercourse as a means of preventing pregnancy.
The latter was allowed because anal intercourse was considered equivalent to vaginal intercourse in this way; men were said to "take it like a woman" muliebria pati, "to undergo womanly things" when they were anally penetrated, but when a man performed anal sex on a woman, she was thought of as playing the boy's role. Larco Museum Collection In Japan, records including detailed shunga show that some males engaged in penetrative anal intercourse with males,  and evidence suggestive of widespread male-female anal intercourse in a pre-modern culture can be found in the erotic vases, or stirrup-spout pots, made by the Moche people of Peru; in a survey, of a collection of these pots, it was found that 31 percent of them depicted male-female anal intercourse significantly more than any other sex act.
Therefore, the reverse of common practices was often portrayed. The Larco Museum houses an erotic gallery in which this pottery is showcased.