<prompt> Investigation of choice for Zenkers diveculum is:Barium swallowEndoscopyEsophageal MenometryCT  <response>: A i.e. Barium swallow: Zenker pharygo-esophageal diveiculum is an acquired pulsion diveiculum herniating through Kilian dehiscenceQ, an area of congenital weakness between the horizontal oblique fibers of cricopharyngeus muscle. It is outpouching of posterior hypopharyngeal wall mucosa sub mucosa through oblique transverse muscle bundles pseudo-diveiculum of cricopharyngeal muscle at pharyngoesophageal junction in the midline of Killian dehiscence triangle of Laimer, at level of Cs-_ It may present with upper oesophageal dysphagia as diveiculum fills preferentially Zeinker diveiculum Posterior with food obstructs the lumen of oesophagus, compressible neck mass, regurgitation - aspiration of undigested pouch content food, noisy deglutition and halitosis foul breath. Aspiration 30, perforation carcinoma 0.5 are possible complications. - X-ray demonstrates air fluid level in superior mediastinum. Barium swallow is investigation of choiceQ and demonstrates barium filled sac or bulge extending posterirly just above cricopharyngeal impression in upper half of semilunar depression on lateral view; extending caudally usually to the left below the arcuate line of piriform sinuses on frontal view with paial or complete obstruction of oesophagus from external pressure of sac contents. - Once suspected, clinically radiologically, the diagnosis of Zenkers diveiculum is estabilished by barrium swallomQ. No other study is often required. Endoscopy is usually difficult potentially dangerousQ, owing to obstruction of true oesophageal lumen by the diveiculum 1t increased risk of diveicular perforation. Killian-Jamieson Pouch diveicula are protrusion arising on anterolateral wall of proximal cervical oesophagus just below the level of cricopharyngeus, in region of anatomic weakness caused by passage of inferior laryngeal nerve. 