Anatomy of the Anus
The anus is the last part of the digestive tract. it's at the end of the rectum. It's where stool comes out of the body. It consists of a muscular ring (called a sphincter) that opens during a bowel movement to allow stool (feces) to pass
through, as well as flat cells that line the inside of the anus.
Most anal cancers start in these flat lining cells. These are also called squamous cells. The lower part of the anus, where it meets the skin, is called the anal margin.
Anus Conditions
Internal hemorrhoids: Swollen veins inside the anus or rectum. These cannot be seen from outside the body.
External hemorrhoids: Blood vessels that swell near the opening of the anus or bulge outside.
Anal cancer: Cancer of the anus is rare. Infection with human papillomavirus (HPV), anal
sex, and multiple sexual partners increase the risk.
Anal herpes: Anal sex may spread the herpes viruses HSV-1 and HSV-2. Symptoms include
painful sores around the anus that come and go.
Anal warts: Infection by the human papillomavirus (HPV) can lead to warts in and around the anus.
Anal fistula: An abnormal channel developing between the anus and the skin of the buttocks. Inflammatory bowel disease (Crohn's and ulcerative colitis) or previous surgery are common causes.
Anal fissure: A tear in the lining of the anus, often caused by constipation. Pain, especially with bowel movements, is the main symptom.
Anal abscess: A pocket of infection in the soft tissue around the anus. Antibiotics and surgical drainage may be required to effectively treat an abscess of the anus.
Anal itching: Itching in or around the anus is a common problem. In most cases, no serious cause is responsible.
Proctalgia fugax: Sudden, severe pain in the area of the anus and rectum, lasting seconds or minutes, then disappearing. The cause is unknown.
Constipation: Difficulty passing stools is common, and can cause anal pain, anal fissures, and bleeding from hemorrhoids.
Anal bleeding: Bright red blood from the anus is sometimes from hemorrhoids, but requires evaluation to rule out a more serious cause.
Anus Tests
Physical examination: A doctor may inspect the outside of the anus, and insert a gloved finger to feel for abnormal areas on the inside of the anus. Sigmoidoscopy: An endoscope (flexible tube with a lighted camera on its tip) is inserted into the anus and moved into the colon. Sigmoidoscopy can only reach part of the colon for viewing.
Colonoscopy: An endoscope is inserted into the anus, and the entire colon is viewed to look for problems.
Fistulography (fistulogram): A liquid that helps improve image contrast is injected into an abnormal opening in or near the anus, and X-ray films are taken. Fistulography can detect an abnormal connection (fist | +.--nthe anus
and skin. Q)
All blood vessels are lined with a thin layer of simple squamous epithelium known as the endothelium that keeps blood cells inside of the blood vessels and prevents clots from forming. The endothelium lines the entire circulatory system, all the way to the interior of the heart, where it is called the endocardium.
There are three major types of blood vessels: arteries, capillaries and veins. Blood vessels are often named after either the region of the body through which they carry blood or for nearby structures.
For example, the brachiocephalic artery carries blood into the brachial (arm) and cephalic (head) regions. One of its branches, the subclavian artery, runs under the clavicle; hence the name subclavian. The subclavian artery runs into the axillary region where it becomes known as the axillary artery.
Blood
The average human body contains about 4 to 5 liters of blood. As a liquid connective tissue, it transports many substances through the body and helps to maintain homeostasis of nutrients, wastes, and gases. Blood is made up of red blood cells, white blood cells, platelets, and liquid plasma.