How do you breathe using your diaphragm?

Answer 1

The diaphragm will move downward in your body creating a vaccum in you lungs and around them. Certain physical laws maintain that where there is no matter (a vaccum) the space must be filled where possible and so you lungs take in air and expand to fill the space. Also the muscles around your ribs called the inter-costal muscles contract and pull your ribcage outward slightly to allow room for lungs to expand