Expansion
The right main bronchus is Wider, Shorter and more Vertical
Expansion
The right main bronchus is:
- Wider
- Shorter - about 2.5 cm, against 5 cm on the left
- More Vertical
So inhaled material takes the path of least resistance to the right. The commonest destinations are the posterior segment of the right upper lobe in a supine patient and the basal segments of the right lower lobe in an upright one.
The same anatomy explains endobronchial intubation: if the tube is advanced beyond the carina it enters the right main bronchus, and the left lung is not ventilated. Check for absent left-sided breath sounds and withdraw.