00:00 / 00:00
Anal conditions: Clinical
0 / 11 complete
The top and bottom of the anal canal are surrounded by the internal and the external anal sphincters, which are two muscular rings that control defecation.
The internal sphincter is under involuntary control, while the external sphincter is under voluntary control.
Within the anal canal, there are mucosal membrane infoldings that form the anal columns.
Above the dentate line, there’s the mucosa is lined by simple columnar epithelium, and below the dentate line, there’s the anoderm, which has no hair and sebaceous and sweat glands, and is lined by squamous epithelium.
Hemorrhoids are often caused by chronically or recurrently increased abdominal pressure, from a variety of causes.
Complications of hemorrhoids can include anemia due to chronic blood loss; strangulation if the blood supply to an internal hemorrhoid is cut off, leading to ischemia; and thrombosed hemorrhoids, which is when blood pools inside a hemorrhoid and forms clots.
Hemorrhoids are swollen veins in and around the anus. They may cause pain, itching, and bleeding. Anal fissures are tears in the skin around the opening of the anus. They may cause pain and bleeding. Abscesses are collections of pus caused by infection. Fistulas are tunnels that form between two organs or between an organ and the skin. Tumors are solid masses of tissue that form due to abnormal cell growth. They may be cancerous or noncancerous.
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.