EXSPIRATION - EXHALE

EXTERNAL INTRERCOSTAL MUSCLEX RELAX INTERAL INTERCOSTAL MUSCLES CONTRACT PULL DOWN AND IN DIAPHRAGM RELAXES TO MOVE UP AND DOWN PRESSURE IS GREATER THAN ATMOSPHERIC BUT DECREASES AS AIR MOVES OUT LUNG VOLUME DECREASE MOVEMENT OF AIR IS OUT OF THE LUNGS AS PRESSURE IN THORAX IS HIGHER THAN ATMOSPHERIC