42 



PHYSIOLOGY, 

 Fig. 2. 



View of the diaphragm ; 1, cavity of the thorax ; 2, diaphragm sep 

 arating the cavity of the thorax from that of the abdomen ; 3, cavity 

 of the pelvis. 



7.: During the act of inspiration, the diaphragm contracts; 

 the rhuscular fibres shorten themselves, and the muscle de- 

 scends, passing from the fourth rib to below the seventh, 

 losing the arched form, as represented in the cut. At the 

 same time, the muscles of the abdomen are protruded for- 

 wards, and the viscera in its cavity pushed downwards. 

 The degree in which the capacity of the chest is enlarged by 

 these movements is very satisfactorily shown in the follow 

 ing cut. 



