The trachea is not just hollow muscular tube , it has got many cartilage structures (rings) around it , which is usually C shaped. It provides support to the trachea, so even if their is less air it's wall does not tend to collapse.

Structure of the trachea

The trachea is made up of C-shaped rings of cartilage that provide structural support to the trachea. The cartilage rings are incomplete at the back, allowing the trachea to expand when we breathe in air. The front of the trachea is supported by a band of smooth muscle that also helps to keep the trachea open.

The role of air pressure

Air pressure plays a significant role in keeping the trachea open. When we breathe in, the air pressure inside the trachea decreases, and the external air pressure is higher. This difference in pressure creates a force that pulls the walls of the trachea outward, keeping it open.

The role of mucus

The walls of the trachea are lined with a layer of mucus that traps foreign particles and prevents them from entering the lungs. The layer of mucus also helps to lubricate the trachea, allowing air to flow smoothly through it.

The role of the diaphragm

The diaphragm is a large muscle located at the bottom of the lungs that helps with breathing. When we inhale, the diaphragm contracts and moves downward, increasing the space in the chest cavity. This increased space allows the lungs to expand and fill with air, which in turn creates a negative pressure in the trachea, pulling the walls of the trachea outward and keeping it open.

Conclusion

In conclusion, the walls of the trachea do not collapse because of the structural support provided by the C-shaped rings of cartilage, the role of air pressure, the layer of mucus, and the action of the diaphragm. All of these factors work together to keep the trachea open and allow air to flow smoothly through it.