Anal sphincter

Anal Sphincter

The anal sphincter is a group of muscles at the end of the rectum that surrounds the anus, controlling the release of feces from the body. The anal sphincter is an essential part of the digestive system and plays a crucial role in maintaining continence.

Anatomy

The anal sphincter is composed of two main parts: the inner anal sphincter and the outer anal sphincter. The inner sphincter is involuntary, meaning it is not under conscious control, and is composed of smooth muscle. The outer sphincter is voluntary, meaning it can be consciously controlled, and is composed of skeletal muscle.

Function

The primary function of the anal sphincter is to control the expulsion of feces from the body. When the rectum is full, the increase in pressure triggers the desire to defecate. The inner sphincter relaxes, allowing feces to enter the anal canal. The outer sphincter then relaxes to allow the feces to be expelled from the body.

Disorders

Disorders of the anal sphincter can lead to conditions such as fecal incontinence and anal fissure. Fecal incontinence is the inability to control bowel movements, leading to unexpected leakage of stool. An anal fissure is a small tear in the thin, moist tissue (mucosa) that lines the anus, often caused by passing hard or large stools.

Treatment

Treatment for disorders of the anal sphincter often involves a combination of medication, dietary changes, and in some cases, surgery. Medications can help to control diarrhea or constipation, which can contribute to fecal incontinence. Dietary changes can help to regulate bowel movements. Surgery may be necessary in cases where the sphincter muscle has been damaged or weakened.

See Also

• Digestive system
• Fecal incontinence
• Anal fissure