<prompt> Constrictions of esophagus when measured from upper incisiors are present at15 cm, 20 cm , 40 cm15 cm, 25 cm, 25 cm20 cm, 30 cm, 40 cm30 cm, 40 cm, 60cm  <response>: The second constriction is at 25 cm from the upper incisor teeth, where it is crossed by the aoic arch and left main bronchus. The third constriction is at 40 cm from the upper incisor teeth, where it pierces the diaphragm; the lower esophageal sphincter LES is situated at this level. ref - BDC vol2 , britannica.com 