The diaphragm is the main muscle of breathing. In quiet breathing, when the body is at rest, it is believed that the diaphragm does something like 75% of the work of breathing.
The diaphragm is shaped like two upside-down bowls sitting inside the ribcage. It attaches to bottom of the breastbone, the insides of the lower six ribs, and the spine.
When the diaphragm contracts, it flattens out and lowers into the abdominal cavity. As the diaphragm contracts, the volume of the lungs increases and air flows into the lungs. As the diaphragm relaxes, it rises back into the ribcage, the volume of the lungs decreases, and we exhale.
While the diaphragm’s main job is breathing, it can also play a role in stabilizing the spine.
