Final answer:
The skeletal muscle in the esophagus is found in the muscularis externa of its upper third.
Step-by-step explanation:
Skeletal muscle is found in the muscularis externa of the upper third of the esophagus. The histology of the esophagus reveals that the muscularis layer changes according to its location: it is composed of skeletal muscle in the upper third, a combination of skeletal and smooth muscle in the middle third, and exclusively smooth muscle in the lower third. This muscle composition allows the esophagus to effectively transfer food from the mouth to the stomach through peristaltic movements, with the help of the upper and lower esophageal sphincters controlling the entry and exit of food respectively.