What are the esophageal zones in esophageal spasm?

Updated: Aug 07, 2019
  • Author: Ahmad Malas, MD; Chief Editor: BS Anand, MD  more...
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The upper zone is composed entirely of striated muscle. This zone initiates the contractions that propel the food bolus down the esophagus. The upper esophageal sphincter (UES), named the cricopharyngeus muscle, is located in the upper zone.

The middle zone is composed of striated and smooth muscle. The inner circular muscle layer and the outer longitudinal muscle layer work in conjunction to propel the food bolus down the esophagus.

The lower zone contains the lower esophageal sphincter (LES). This sphincter is a thickening of the smooth muscle that is contracted tonically to prevent reflux. At rest, the pressure in the LES is usually 15-25 mm Hg. For food to pass into the stomach, the LES relaxes at the appropriate time.

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