Zenker’s diverticulum is a rare pulsion disorder consisting of an esophageal mucosal herniation posteriorly between the cricopharyngeal muscle and the inferior pharyngeal constrictor muscle (at the junction of the pharynx and esophagus). It is actually a false diverticulum. Zenker’s diverticulum is also called pharyngoesophageal diverticulum.

The frequency of occurrence of Zenker’s diverticulum in the United States and Europe is estimated to range from 0.01% to 0.11% of the population. The disorder is rare in the Middle East and Asia. Women are affected more frequently than men. The disorder is more often seen in the elderly, with age of onset typically occurring between 60 to 80 years.

Zenker’s diverticulum does not occur in any animal other than humans, so the etiology is poorly understood. Theoretically, the patient with Zenker’s diverticulum has relaxation of the cricopharyngeal muscle that is poorly or improperly synchronized with the act of swallowing. The resultant increased pressure is cumulative, over time producing the posterior herniation of the esophageal mucosa between the inferior pharyngeal constrictor muscle and the cricopharyngeal muscle.