182 SURGICAL APPLIED ANATOMY. [Chap. x. 



deposits are more commonly met with in the lung 

 than in any other of the viscera. 



Lung cavities resulting from tuberculosis, gan- 

 grene, or bronchiectasis, have been successfully incised 

 and drained, and the same measure has been applied 

 to hydrated cysts of the lung. 



The trachea divides opposite the junction of the 

 manubrium and gladiolus in front, and the fourth 

 dorsal vertebra behind (Fig. 33). In the newly born 

 the trachea bifurcates opposite the third vertebra 

 (Symington). 



Certain foreign substances that have been drawn 

 into the air passages have shown a remarkable facility 

 for escaping through the parietes. Thus Mr. Godlee 

 records the case of a child, from an abscess in whose 

 back a head of rye-grass escaped, that had found its 

 way into the air passages forty-three days previously. 



The heart. The relations of the heart to the 

 surface are as follows. Its upper limit corresponds 

 to a horizontal line crossing the sternum about the 

 upper border of the third cartilages. Its right border 

 to a curved line arching from the third right cartilage 

 at the sternum to the seventh right chondro- sternal 

 articulation, and reaching about 1^ inches from the 

 middle line. Its lower border follows a line from the 

 seventh right chondro-sternal articulation to the apex. 

 Its apex is opposite the fifth interspace, at the junction 

 of the ribs with these cartilages. Its base is opposite 

 the sixth, seventh, and eighth dorsal vertebrae. Its 

 left border is represented by an arched line drawn from 

 the apex to the third left cartilage at the sternum. 



The orifice of the pulmonary artery is behind the 

 tipper edge of the third left cartilage close to the 

 sternum. The vessel proceeds upward under cover 

 of the second left cartilage. The aortic orifice is behind 

 the left border of the sternum close to the lower edge 

 of the third cartilage. The trunk ascends behind the 



