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Quick Test posted on 6.25.09:
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Esophageal Motility
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Physiology
The coordinated activity of the upper esophageal sphincter (UES), the esophageal body and the lower esophageal sphincter (LES) is responsible for the motor function of the esophagus.
Upper Esophageal Sphincter
The upper esophageal sphincter receives motor innervation directly from the brain (nucleus ambiguous). The sphincter is continuously in a state of tonic contraction, with a resting pressure of about 100 mm Hg (anteroposterior axis). The sphincter prevents passage of air from the pharynx into the esophagus and reflux of esophageal contents into the pharynx. During swallowing, a food bolus is moved by the tongue into the pharynx, which contracts while the UES relaxes. After the food bolus has reached the esophagus, the UES regains its resting tone.
Esophageal Body
When food passes through the UES, a contraction is initiated in the upper esophagus, which progresses distally toward the stomach. The wave initiated by swallowing is referred as primary peristalsis (Figure 20–2). It travels at a speed of 3 to 4 cm/s and reaches peak amplitudes of 60–140 mm Hg in the distal esophagus. Local stimulation by distention at any point in the body of the esophagus will elicit a peristaltic wave from the point of stimulus. This is called secondary peristalsis and aids esophageal emptying when the primary wave has failed to clear the lumen of ingested food or when the gastric contents reflux from the stomach. Tertiary waves are considered abnormal, but they are frequently seen in elderly subjects who have no symptoms of esophageal disease.
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| Fig. 20-2: Deglutition. Normal esophageal peristaltic waves and pressures during consecutive swallows. Note the orderly downward progression of the waves. |
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Quick Test Questions QUESTION 1: The most common primary esophageal motility disorder is
QUESTION 2: Which of the following is the most effective treatment for achalasia?
QUESTION 3: Pharyngoesophageal dysfunction is often caused by
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