A Zenker's diverticulum is a pouch that forms off the back wall of the esophagus. Food particles get caught in this pouch and swallowing is difficult. The problem originates from an overly tight cricopharyngeus muscle, which sits at the top of the esophagus and just below the development of the Zenker's pouch. Over many years, the pressures in the throat caused by swallowing against a tight cricopharyngeus muscle creates a weak spot in the back wall of the esophagus, and gradually a pouch or "diverticulum" forms.
A Zenker's diverticulum can be treated with surgery through the neck and the pouch is removed. However, most of the time, the diverticulum can be treated endoscopically through the mouth (without any cuts in the neck). The cricopharyngeus muscle is divided endoscopically either with a laser or with a stapler device, and there is no more obstruction for swallowing.