What is the role of the esophageal middle zone in the pathophysiology of esophageal spasm?

Updated: Aug 07, 2019
  • Author: Ahmad Malas, MD; Chief Editor: BS Anand, MD  more...
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The middle zone propels the food bolus from the upper zone to the lower zone. This segment consists of two muscle layers, an inner circular layer and an outer longitudinal layer.

In the middle zone, the striated muscle transitions to the smooth, or involuntary, muscle. The wave propagates down the esophagus by coordinated contractions. Again, the longitudinal muscles must contract before the circular muscle contracts. Furthermore, the contraction of the muscles must proceed caudally in an organized manner. If the muscle contraction is not orderly, the food bolus cannot progress effectively.

Two forces propel the food from cephalad to caudad. First, gravity pulls the food caudally. Second, the organized contractions of the muscles propel the food caudally. If a myotomy is performed, the contractions will be ineffective. Only gravity propels the food caudally. Thus, patients who have had a myotomy can be more likely to report dysphagia.

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