WebMD provides a medical diagram of the anus and explains its function and problems that can affect the anus.
MedlinePlus Trusted Health Information for You. Menu The anus is the opening of the rectum through which stool passes out of your body.
Anal swelling can occur for a variety of reasons. Most causes of a swollen anus are temporary and harmless, but some require medical.
Overview of the Anus and Rectum - Explore from the MSD Manuals - Medical Consumer Version.