In the esophagus, the composition of the muscularis externa changes from the superior to the inferior end. Which of the following best describes the muscle type in the middle third of the esophagus?
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Correct answer: A mixture of skeletal and smooth muscle
The upper third of the esophagus is skeletal muscle (under voluntary control during swallowing), while the lower third is entirely smooth muscle. The middle third represents a transition zone containing both muscle types.
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