Schatzki Ring Distal Esophagus

A 62-year-old man presents with a one-year history of intermittent solid-food dysphagia characterized by sudden food impaction episodes occurring every 4–6 weeks, typically with poorly chewed meat or bread ("steakhouse syndrome"). Between episodes, he swallows solids and liquids normally. Upper endoscopy and barium swallow reveal a smooth, thin, symmetric mucosal ring at the squamocolumnar junction (marked **A** in the diagram) with a luminal diameter of 12 mm, and a small sliding hiatus hernia below. There is no stricture, eosinophilic esophagitis, or malignancy. Which of the following best describes the pathophysiologic mechanism of dysphagia in this patient?