The Muscles of Respiration

Please look closely at this illustration by the great anatomical illustrator Netter, and see what you can learn from it.

Note that the muscles marked with blue arrows on the left side of the image are the muscles involved in inspiration (breathing in). They are divided into two groups, principal muscles of inspiration, and accessory muscles. Generally speaking, the principal muscles are used in every breath, and the accessory muscles, though they may also participate at any time, are activated when extra breath is needed.

The right side of the picture shows the muscles involved in expiration (breathing out). As you can see, in quiet breathing, no muscles are activated. "Expiration," the caption says, "results from passive, elastic recoil of the lungs, rib cage and diaphragm." Note that in the Sounder Sleep System, all the breathing we do is quiet breathing only.

In active breathing, muscles are activated. However, that is generally not going to happen in the practice of the Sounder Sleep System.

Therefore, this picture clearly demonstrates that for us, breathing in is an active process, while breathing out is a passive process.

Please make a note of this. It's important! Breathing has an active phase and a passive phase. You need to know that. We will build on this knowledge as we move forward.