Pulmonary VentilationOnline version Define and distinguish between the various pulmonary volumes and capacities by Allison Smithwick 1 Group One 2 Group 2 inhaling exhaling Boyle's Law diaphragm muscles intercostal muscles air pressure in the atmosphere is higher than in the lungs (air flows into the lungs0 air pressure in the lungs is higher than in the atmosphere (air flows out of the lungs) the pressure of a gas in a closed container is inversely proportional to the volume of the container dome-shaped muscle sheet that sits underneath the lungs muscle groups that are situated in between the ribs that create and move the chest wall