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• Zenker's diverticula (ZD) is thought to be due to the result of motor abnormalities of the esophagus.
• ZD emerge from a defect within the Killian's triangle that's a natural place for the weak point of the muscular wall of the hypopharynx.
• Killian's triangle is formed by the oblique fibers of the inferior pharyngeal constrictor muscle and the cricopharyngeal sphincter.
• This posterior pouch includes only mucosa and submucosa, thus, a ZD should be considered a pseudodiverticulum.
• Chronic strain on the Killian's triangle leads to an evagination of the sphincter, which may be because of the following

● High pressures in the food bolus in the course of swallowing ● Difficulty in swallowing because of abnormalities of the upper esophageal sphincter (UES)

• This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the hypopharyngeal pressure gradient.
• The consequences of numerous studies illustrate the kinds of observations made in patients with ZD
• A variety of situations predisposing to herniation within Killian's triangle, inclusive of atypical esophageal motility, esophageal shortening, or disorders related to altered u.s.function.
• Increased intrabolus pressures found in patients with ZD can be secondary to impaired bolus passage in combination with or as a result of gastroesophageal reflux disease.
• An unanswered question is how spasms of UES provoked by acid reflux should cause improved intrabolus pressures during swallowing, given that swallowing is often distinct from episodes of acid reflux disorder.
• As the diverticulum enlarges, it may compress the pharyngoesophageal segment as well as increased stiffness and the intrabolus pressure.
• Increased intrabolus pressure is also increased in older patients who perform multiple swallows to achieve bolus clearance.
• Finally, incoordination of pharyngeal contraction and UES opening has also been variably demonstrated by some investigators