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What is Which muscle causes opening of the upper end of esophagus? and explain in detail?
Ans. is 'd' i.e., Cricopharyngeus of inferior constrictor Upper esophageal sphinctor* The upper esophageal sphincter surrounds the upper part of the esophagus.* It consists of skeletal muscle, but is not under voluntary control.* Opening of the upper esophageal sphincter is triggered by the swallowing reflex.* The primary muscle of the upper esophageal sphincter is the cricopharyngeal part of the inferior pharyngeal constrictor.