Esophageal diverticula are a group of diseases characterized by outpouching of one or more layers of the esophageal wall and classified by location. Zenker diverticulum (ZD) (pharyngoesophageal diverticulum, pharyngeal pouch) is a "false" diverticulum that is characterized by herniation of the esophageal mucosa and submucosa just above the upper esophageal sphincter. The etiology for the development of ZD remains unclear. However, it is suspected that incomplete upper esophageal sphincter relaxation leads to increased intraluminal pressure. The location where ZD forms is at an area of relative luminal wall weakness, which over time leads to a protruding diverticulum.

Patients with ZD initially present with transient oropharyngeal dysphagia that can progress to regurgitation of food, pulmonary aspiration, or appearance of a neck mass as the sac enlarges (may contain food, pills, sputum, or mucous). As many smaller, subclinical ZD presumably go undiagnosed, the timeline of progression is difficult to quantify. ZD has a slight male predominance (1.5:1), is associated with advanced age, and is more common in people from North America, Northern Europe, and Australia. Although ZD is the most common of the esophageal diverticula, it is relatively uncommon, seen in 1:5000-10 000 patients.