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". 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.