In erect posture commonest siteof foreign body in bronchus
Foreign bodies like pins,coins entering the trachea pass into the right bronchus,which is wider,more veical & is in line with trachea.Most of the human beings want to take the path of least resistance,so the foreign bodies in the trachea travel down into right bronchus and then into posterior basal segments of the lower lobe of the lung. Reference:B D Chaurasia's Human anatomy-Volume 1,5th edition,page no:288
Right lower lobe
Right upper lobe
Carina
Left lower lobe
Cardio thoracic surgery  