Where is anus

The anus is lined with a continuation of the external skin. A muscular ring anal sphincter keeps the anus closed until the person has a bowel movement. See also Overview of the Digestive System Overview of the Digestive System The digestive system, which extends from the mouth to the anus, is responsible for receiving food, breaking it down into nutrients a process called digestion , absorbing the nutrients into Merck and Co.

From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world. The Manual was first published in as a service to the community. Learn more about our commitment to Global Medical Knowledge. This site complies with the HONcode standard for trustworthy health information: verify here. Common Health Topics. Biology of the Digestive System. Most nearly 9 out of 10 cases anal cancers in the United States are squamous cell cancer.

These tumors start in the squamous cells that line most of the anal canal and the anal margin. Squamous cell cancers in the anal canal have grown beyond the surface and into the deeper layers of the lining. Squamous cell cancers of the anal margin perianal skin can be treated as an anal cancer or like squamous cell cancer of the skin.

It is important to see an expert if you are diagnosed with perianal cancer to determine the best course of treatment. The anal cancer information here focuses mainly on anal squamous cell carcinoma since it is the most common type of anal cancer. A small number of anal cancers are adenocarcinomas. These cancers start in cells that line the upper part of the anus near the rectum. They can also start in the glands under the anal mucosa that release secretions into the anal canal.

Most anal adenocarcinomas are treated the same as rectal carcinomas. For more information, see Colorectal Cancer. Adenocarcinomas can also start in apocrine glands a type of sweat gland of the perianal skin. Basal cell carcinomas are a type of skin cancer that can develop in the perianal skin.

These tumors are much more common in areas of skin exposed to the sun, such as the face and hands. Very few anal cancers are basal cell carcinomas. They are often treated with surgery to remove the cancer. These cancers start in cells in the skin or anal lining that make the brown pigment called melanin. Glandular cells make mucus. This helps poo pass through the anus. The anus.

The anus is the opening at the end of the large bowel. Stools pass through the anus when leaving the body. See also Anal cancer Anorectal melanoma. How we can help. If you need to talk, we'll listen.