RESPIRATION 



chest not occupied by the heart and its connected blood- 

 vessels and supporting tissues, by the esophagus and 

 the trachea. As we have seen, the walls of the lungs are 

 in close. contact with the inside walls of the chest cavity. 

 Below they are in similar contact with the diaphragm, 

 a partition made up of muscle and tendon, which sepa- 

 rates the chest cavity from the abdominal cavity. All 

 outward and inward movements of the chest wall and 



Vena cava 

 Sternum 

 Cartilages of ribs 



Aorta 



Central tendon of diaphragm 



Esophagus 



Pillars of diaphragm 



FIG. 102. Front view of tiie diaphragm and its attachments. 



downward and upward movements of the diaphragm, 

 are accompanied by an equal enlargement and reduction 

 of the lungs, so that there is never any separation of 

 the pleural surfaces. 



Air movement. Associated with each enlargement of 

 the lung there is an intake, or inspiration, of air; and 



