The upper esophageal sphincter, which doctors may also call the pharyngoesophageal sphincter ... or who have had a stroke often have dysphagia from upper esophageal dysfunction.

Responses to 1- and 5-mL water boluses are shown. Note that with the smaller 1-mL bolus, UES relaxation is complete and there is only a small intrabolus pressure (shaded). With the larger 5-mL ...