when you breathe in, air enters the lungs. while, when you breathe out, air leaves the lungs. what is the main muscle that aids in the passage of air into and out of the lungs?

The main muscle that aids in moving air into and out of the lungs is the diaphragm. It’s a dome-shaped sheet of muscle under your lungs that:

• Contracts and flattens when you breathe in, increasing chest space so air is pulled into the lungs.

• Relaxes and returns to its dome shape when you breathe out, helping push air out of the lungs.