The normal narrowing in the middle of the oesophagus is caused by
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
Azygos vein
Hemiazygos vein
Right main stem bronchus
Left main stem bronchus
Thorax