PE - mechanics if breathing

 Diaphragm contracts
  External intercostals contract
 Diaphragm flatterns / pushed down
 Ribs/sternum move up and out
 Thoracic cavity volume increases
Lung air pressure decreases below atmospheric air
   Air rushes into lungs

Diaphragm relaxes
External intercostals relax
Diaphragm pushes upwards
Ribs / sternum move in and out
Thoracic cavity volume decreases
Lung air pressure increases above atmospheric air
Air riches out of the lungs

sternocleidomasoid contract
scalens contract
pectoralis major contract
diaphram flatterns with more force
increased lifting of ribs / sternum
increased thoracic cavity volme
lower air pressure in the lungs
more air rushes into the lungs

internal intercostals contract
rectus abdominus/obliques contract
diaphram pushes up harder with more force
greater decrease in thoracic cavity volume
higher air pressure in the lungs
more air pushes out of the lungs