Final answer:
The upper esophageal sphincter is made up of skeletal muscle and controls the movement of food from the pharynx to the esophagus.
Step-by-step explanation:
The upper esophageal sphincter is part of the mechanism involved in the passage of food through the esophagus. This sphincter, specifically, is responsible for controlling the movement of food from the pharynx into the esophagus. When considering its muscular composition, the upper esophageal sphincter is made up of skeletal muscle, which is under voluntary control, in contrast to the lower esophageal sphincter which involves smooth muscle.