182 



UNCONSCIOUS NERVOUS OPERATIONS 



255. The Trachea is a large tube of from sixteen to 

 twenty incomplete cartilaginous rings (Fig. 100). It is 

 from four to four and a half inches in length, from the 



Fig. 100. Diagram of the respiratory organs. 



cricoid cartilage, to which it is attached above, to its 

 lower extremity, where it divides into two bronchi, one 

 of which goes to each lung. At the back of the trachea, 

 between the ends of the cartilage rings, are bands of plain 



