Question

why do the walls of the trachea not collapse when there is less air in it?

Answer 1

The trachea is not a very collapsible organ like the oesophagus or the food pipe.

So there needs to be a force.

This force helps in the movement of trachea.

This leads to the closing of trachea which is not possible when the air is less.

This is because there is no force and force is required for it.

Answer 2

Walls of trachea have incomplete C-shaped rings present which ensure that it does not collapse when there is less air in it.