(Inspiration) The intercostal muscles to move the ribcage and

(Inspiration) The diaphragm (flattens)

(Inspiration) The volume in the cavity

(Inspiration) The pressue in the cavity so it is than the pressue of the air

(Expiration) The intercostal muscles to push the rib cage and

(Expiration) The volume and the pressure , forcing air out

(Expiration) The abdominal muscles to the diaphragm

(Inspiration) Air flows down the gradient and into the