Question

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

Answer 1

Walls of trachea not collapse because there are rings of cartilage which avoid them to collapse.

Answer 2

The trachea is supported by c-shaped rings of cartilage which hold them in place when there is less air inside it. Due to this, the walls of trachea do not collapse even when there is a little air.