Anus and prostate

Your anus is located on your backside, between your butt checks. Your anus is closed off by two rings of muscle: the internal anal sphincter and the external anal sphincter. Around the anus there are 'corpora cavernosa' or masses of erectile tissue that prevent moisture and air from escaping unintentionally.

Anus and sphincters

The anus is the last part of the rectum. It is closed off by two rings of muscle called sphincters. The external anal sphincter is located approximately 1 cm from the opening of your anus. You can flex and relax this muscle on your own, just as you can flex and relax the muscles in your arms and legs. 

The internal anal sphincter is situated 0.5 cm deeper inside your anus. You can't consciously relax this second sphincter on your own.  The internal anal sphincter will only relax when a light pressure is applied, for example, from a stool on the inside that is ready to be discharged, or from a finger or penis from the outside. If you feel relaxed, the internal anal sphincter will relax more easily.  

'Corpora cavernosa'

Besides the sphincters, the networks of blood vessels (known as corpora cavernosa) inside the anus ensure that moisture and air will not escape when you don't want them to. If too much pressure is applied, these blood vessels can stick out, which can lead to haemorrhoids.

Relaxing your sphincter

If your sphincters are not relaxed enough, it can feel very unpleasant, or even painful, if someone's finger or penis goes inside. Start slowly, take it easy and listen to your body. Breathing in and out slowly can help you train your sphincter to relax more easily.

Prostate

From inside your rectum you can feel your prostate about 5 cm past your sphincter on your stomach side. Your prostate makes sure your urethra is closed off during an ejaculation (when you come). That way, the sperm can only go in one direction: out through the penis.  Your prostate also adds certain other substances to the sperm.

Erogenous zones

The area around your prostate and your anus has many nerve endings. That is why the anus and the prostate are very sensitive erogenous zones. It something touches your prostate during sex, for example a finger or a penis in your anus, that will give you an exciting sensation.  That is why the prostate is also known as the male G spot. 

Fragile mucous membrane

The inside of your anus and rectum is covered with mucous membrane. This mucous membrane is very fragile and can be easily damaged, which means blood can enter your intestines.  The mucous membrane also easily absorbs viruses. That is why having anal sex without a condom puts you at more risk of becoming infected with HIV or other STIs, regardless of whether you are fucking actively or being fucked. 

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