The normal narrowing in the middle of the oesophagus is caused by: (A) Azygos vein, (B) Hemiazygos vein, (C) Right main stem bronchus, (D) Left main stem bronchus
Answer is D. Middle constriction of oesophagus is due to left bronchus .27.5cm/11 inch from insisor teeth. BD CHAURASIA&;S HUMAN ANATOMY VOLUME 1, 6TH Edition . page no 282, fig 20.7