Lower esophageal sphincter lies at what distance from the incisor teeth?: (A) 15cm, (B) 25cm, (C) 40cm, (D) 50cm
Answer is C. Ans. is 'c' i.e., 40cm * 2nd constriction is at T4 level where arch of aorta crosses esophagus.Esophageal constrictionsNumberDistance from incisorBony levelAnatomical landmark1st15 cm (6 inches)C6At its beginning (pharyngo-esophageal junction)2nd22.5 cm (9 inches)T4Crossing of aortic arch3rd27.5 cm (11 inches)T6Crossing of left main bronchus4th37.5 - 40 cm (15-16 inches)T10Piercing diaphragm (at lower esophageal sphmotor)