Back in elementary school, you probably heard a zillion jokes with the punch line: "Uranus!" But seriously, how much do you really know about your anus? Learning about this key piece of anatomy may seem like a laughing matter — but it's an important part of sexual health for many women and men. Read on to get the lowdown on the anus: what it is, why it's important, and how to keep it healthy.

Anal Info

The anus is the opening at the end of the rectum from which solid waste (feces) leaves the body. It's located right between the buttocks — behind the vagina in women and behind the testicles in men. Muscles inside and outside the anus, called "sphincters," open to let feces out or close to hold it in.

The anus is full of thousands of nerve endings both inside and outside, making it very sensitive. For some people, the anus is an erogenous zone that can respond to sexual touch and stimulation. For others, it's a hands-off zone that needs to be respected. It's okay to enjoy anal stimulation, and it's also okay to dislike it — both preferences are common.

Anal Sex

Anal sex play is often associated with gay men. However, many men and women, regardless of whether they're gay, lesbian, straight, or bisexual, enjoy anal stimulation. And many, including gay men, don't. Some straight couples use anal sex as a way to preserve the woman's virginity. For those who like it, anal stimulation can be part of masturbation, intercourse, or oral sex.

Anal intercourse is sex play that involves insertion of the penis or a sex toy into the anus. "Rimming" is slang for oral stimulation of the anus. Both acts, if unprotected, can put each partner at risk for various intestinal parasites, hepatitis, herpes, and other sexually transmitted infections. Unprotected anal intercourse is, of course, high risk for HIV. Proper use of latex barriers — condoms for anal intercourse and Sheer Glyde dams for rimming — can reduce the risk of contracting an infection. It's important to use a water-based lubricant with condoms — it makes anal sex feel better and makes condoms less likely to break.

Anal Health

Hygiene is important for good anal health, but there's no need to overdo it. Washing daily 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. Penetration with a penis or sex toy can irritate or tear the inside of the anus. Use common sense — pay attention to how your body feels during anal stimulation, and stop if you feel pain or discomfort. And if you do play with sex toys for anal sex, make sure to use condoms on them and keep them clean, especially if they are shared.

The anus is a frequent site of sexually transmitted infection. If you notice any pain, sores, discharge, or lumps around or inside the anus, make an appointment with a clinician as soon as possible. The staff at the nearest Planned Parenthood health center can help you out, too.