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November 21, 2009
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Achalasia

Medical Author: Jay W. Marks, MD
Medical Editor: Dennis Lee, MD

What is achalasia?

Achalasia is a rare disease of the muscle of the esophagus (swallowing tube). The term achalasia means "failure to relax" and refers to the inability of the lower esophageal sphincter (a ring of muscle between the lower esophagus and the stomach) to open and let food pass into the stomach. As a result, patients with achalasia have difficulty swallowing food.

How does the normal esophagus function?

The esophagus has three functional parts. The uppermost part is the upper esophageal sphincter, a specialized ring of muscle that forms the upper end of the tubular esophagus and separates the esophagus from the throat. The upper sphincter remains closed most of the time to prevent food in the main part of the esophagus from backing up into the throat. The main part of the esophagus is referred to as the body of the esophagus, a long, muscular tube approximately 20 cm (8 in) in length. The third functional part of the esophagus is the lower esophageal sphincter, a ring of specialized esophageal muscle at the junction of the esophagus with the stomach. Like the upper sphincter, the lower sphincter remains closed most of the time to prevent food and acid from backing up into the body of the esophagus from the stomach.

The upper sphincter relaxes with swallowing to allow food and saliva to pass from the throat into the upper esophageal body. The muscle in the upper esophagus just below the upper sphincter then contracts, squeezing food and saliva further down into the esophageal body. The ring-like contraction of the muscle progresses down the body of the esophagus, propelling the food and saliva towards the stomach. (The progression of the muscular contraction through the esophageal body is referred to as a peristaltic wave.). By the time the peristaltic wave reaches the lower sphincter, the sphincter is open, and the food passes into the stomach.



Next: How is esophageal function abnormal in achalasia? »

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Achalasia

Swallowing problems overview

The swallowing tract extends from the mouth to the stomach. The act of swallowing normally occurs in three phases. In the first phase, food or liquid is contained in the mouth by the tongue and palate (oral cavity). This phase is the only one we can control.

The second phase of swallowing begins when the brain makes the decision to swallow. At this point, a complex series of reflexes begin. The food is thrust from the oral cavity into the throat (pharynx). At the same time, two other events occur: A muscular valve at the bottom of the pharynx opens, allowing food to enter the swallowing tube (esophagus), and other muscles close the airway (trachea) to prevent food from entering the airways. This second phase of swallowing takes less than half a second.

The third phase of swallowing begins when food enters the esophagus. The esophagus, which is about nine inches long, is a muscular tube that produces wav...

Read the Swallowing Problems article »










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