What is Zenker's diverticulum and where is it located?

• A. A mucosal pouch in the lower esophagus near the diaphragm
• B. A pharyngoesophageal diverticulum at Killian's dehiscence just above the upper esophageal sphincter
• C. A diverticulum in the stomach near the cardia
• D. A diverticulum in the duodenum near the ampulla

Answer: (B)

Zenker's diverticulum is a pharyngoesophageal (hypopharyngeal) diverticulum that forms as a pouch through Killian's dehiscence, a weakness between the thyropharyngeus and cricopharyngeus muscles just above the upper esophageal sphincter. It is a false diverticulum because mucosa and submucosa herniate through the muscle layer rather than all layers of the esophageal wall. The hallmark is its location in the posterior hypopharynx just above the UES, at Killian's dehiscence. Other described sites — a pouch in the lower esophagus near the diaphragm, a diverticulum in the stomach near the cardia, or a diverticulum in the duodenum near the ampulla — correspond to different diverticula and are not Zenker's.