126 



PHYSIOLOGY AND HEALTH. 



the expanded and contracted chest. The full lines d, d t d, 

 show the size of the cavity when the ribs are drawn down 

 and the diaphragm is expanded upward. The dotted lines 



J? 'IG. XVII. Outline of the Expanded and Contracted Chest. 

 Front View. 



a. Neck. 



b,b,b,b,b,b. 

 panded chest. 



Size of the ex- 



c, c, c. Position of tBe 

 phragm when drawn down. 



dia- 



d,d,d,d,d,d. 

 tracted chest. 



Size of the con- 



e, e, e. Position of the dia- 

 phragm when expanded. 



show its size when the ribs are lifted and the diaphragm 

 drawn down. When the ribs are at rest, they lie downward 

 and inward, and their surface is represented by the lines 

 d, d, d, d, d, d; but, when they are raised, they are carried out- 

 ward, and their surface is represented by the dotted lines 

 b, b, b, b, b, b. When the diaphragm is at rest, it projects 

 upward- in form of the line e, e, e ; but, when it is in ac- 

 tion, it is drawn downward in form of the line c, c, c. 

 The upper point e reaches as high as the fourth rib. The 

 upper point c reaches as high as the seventh rib. It is now 

 very plain that the cavity 6, 6, b, c, c, c, b, b, 6, is larger than 

 the cavity d, d, d, e, e, e, d, d, d, and the difference in size 

 must be in proportion to the extent of the motions of the ribs 

 and the diaphragm. 



