Anal valves

Anal Valves

Illustration of the anal valves and surrounding structures.

The anal valves are small crescent-shaped folds of mucous membrane located in the anal canal. They are part of the anorectal junction and play a role in maintaining continence. The anal valves are situated at the lower end of the anal columns, which are vertical folds in the lining of the anal canal.

Anatomy

The anal valves are found at the distal ends of the anal columns, which are also known as the columns of Morgagni. These columns are formed by the underlying anal sinuses, which are small recesses that open into the anal canal. The anal valves connect adjacent anal columns, forming a series of small pockets known as the anal crypts.

The anal crypts are important because they can become sites of infection or inflammation, leading to conditions such as anal abscesses or anal fistulas. The anal valves themselves are composed of mucous membrane and are supported by connective tissue.

Function

The primary function of the anal valves is to help maintain continence by contributing to the closure of the anal canal. They work in conjunction with the internal anal sphincter and the external anal sphincter to control the passage of stool and gas.

The anal valves also play a role in the sensation of the anal canal, as they are part of the sensitive lining that detects the presence of stool and triggers the urge to defecate.

Clinical Significance

Problems with the anal valves can lead to various anorectal disorders. For example, if the anal crypts become blocked, they can lead to the formation of an anal abscess, which may require surgical intervention. Chronic inflammation or infection of the anal crypts can result in the development of an anal fistula, a tract that forms between the anal canal and the skin around the anus.

In some cases, the anal valves may become hypertrophied or enlarged, which can contribute to symptoms such as discomfort or difficulty with bowel movements.

Related Pages

• Anal canal
• Anal columns
• Anal sphincter
• Anorectal abscess
• Anal fistula