AND PHYSIOLOGY. 



249 



Fig. 250. 



The Larynx, Trachea, and Bronchia, deprived of their Fibrous Covering, and with the 

 outline of the Lungs. 1, 1, Outline of the Upper Lobes of the Lungs. 2, Outline of the 

 the Middle Lobe of the Eight Lung. 3, 3, Outline of the Inferior Lobes of both Lungs. 

 4, Outline of the Ninth Dorsal Vertebra, showing its relation to the Lungs and the Ver- 

 tebral Column. 5, Thyroid Cartilage. 6, Cricoid Cartilage. T, Trachea. 8, Eight 

 Bronchus. 9, Left Bronchus. 10, Crico-Thyroid Ligament. 11, 12, Rings of the Tra- 

 chea. 13, First Eing of the Trachea. 14, Last Eing of the Trachea, which is Corset- 

 shaped. 15, 16, A complete Bronchial Cartilaginous Eing. 17, One which is Bifurcated. 

 13, Double Bifurcated Bronchial Eings. 19, 19, Smaller Bronchial Eings. 20, Depres- 

 sions for the Course of the large Blood- Vessels. 



about one inch in diameter, made up of from fifteen to twenty 

 cartilaginous rings, commencing at a point nearly opposite 

 the fifth cervical vertebra, and extending as low as the second 

 dorsal, or top of the sternum, "where it divides into two bron- 

 chi extending to each lung. These segments of the trachea 

 are not perfect rings, since they complete only about five sixths 



441. How is the trachea made up ? "Where does it divide into the two bronchi ? i*re 

 the segments of the trachea perfect rings ? 



