TRACHEA AND BRONCHIAL TUBES. 



cords together and narrow the glottis. In ordinary quiet 

 breathing the glottis is wide open, and air passes through 

 it without causing sound. When it is narrowed, and air 

 driven through it from the lungs, voice is produced. 

 The sounds produced in the larynx are afterwards 

 altered, and added to, in various 

 ways in the throat, mouth, and 

 nose. Thus voice is altered or 

 improved into speech. 



15. The Windpipe or Trachea 

 (, Fig. 44) is a stiff tube which 

 may be easily felt in the lower 

 part of the front of the neck of 

 thin persons. In its walls are 

 horseshoe - shaped cartilages, 

 which keep it open. The wind- 

 pipe enters the thoracic cavity, 

 and there divides into two bron- 

 chi, one for each lung (d, Fig. 

 44). 



FIG. 44. The larynx, trachea, 



bronchi, and bronchial tubes, seen 16. The Bronchial TUDBS. 



from the front. The right lung 



(to the left in the figure) has Each bronchus, as soon as it 



been dissected away to expose the 



bronchial tubes. a larynx; /, en terS the lung, begins tO divide, 



windpipe; d, right bronchus: its fc>> & 



branches are bronchial tubes. Qver and Qver a g a in, like the 



trunk of a tree. The branches are hollow, and the end 

 ones are very small indeed. They are all named bronchial 

 tubes. On the left side of Fig. 44 the right lung has been 

 cut away, so as to show the bronchial tubes. 



breathing ? How is voice produced ? How is voice converted into 

 speech ? 



15. What is the windpipe? How is it kept open? Where and 

 how does it end? 



16. What is said concerning the bronchial tubes ? 



