<prompt> The distance of aoic constriction of the oesophagus from the upper incisor teeth15 cm22.5 cm27.5 cm40 cm  <response>: First constriction, at the pharyngo-esophageal junction, 9 cm 6 inches from the incisor teeth. Second constriction, where its crossed by the arch of aoa, 22.5 cm 9 inches from the incisor teeth. Third constriction, where its crossed by the left principal bronchus, 27.5 cm 11 inches from the incisor teeth. Fouh constriction, where it pierces the diaphragm, 40 cm 15 inches from the incisor teeth. Ref - sciencedirect.com 