BREATHING 



I6 3 



The upper part of the windpipe is a kind of box called 

 the larynx, or organ of voice. In this box are the vocal cords. 

 In some persons it is very prominent, and the front edge 

 of it is commonly called 

 "Adam's apple "(Figs. 100, 

 173, 174, and 175). 



223. The Bronchial 

 Tubes. The windpipe, 

 after entering the chest, 

 divides into two branches 

 called bronchi, one to each 

 lung. These again divide 

 into smaller tubes called 

 bronchial tubes. 



Each bronchial tube 

 divides again into smaller 

 branches, these again into 

 smaller, and so on to the 

 tiniest twigs many times 

 smaller than the hairs of 

 our head. 



The numberless bron- 

 chial tubes pass to all parts 



of the lungs, and end finally FIG. 101. Larynx, Trachea, and the 



Bronchi. (Front view.) 



, epiglottis ; B, thyroid cartilage ; C, crico- 

 thyroid membrane, connecting with the 

 cricoid cartilage below, all forming 'the 

 larynx ; D, rings of the trachea. 



in clusters of short, blind, 



and somewhat dilated 



pouches called alveoli. 



Each of these closed, 



dilated ends is divided into a number of air cavities or 



air sacs. 



If we remember that all these tubes, great and small, 

 are hollow, we may compare them to a short bush or tree 



