Chap, x.] THE THORAX. 157 



about are often associated with violent respiratory 

 efforts at the time of the accident. In wounds of the 

 lung the blood may escape in three directions : into 

 the tissue of the organ (pulmonary apoplexy), into the 

 bronchi (causing haemoptysis), and into the pleura 

 (causing hsemothorax). In some instances the lung 

 has been ruptured without wound and without frac- 

 ture of the ribs. These cases are difficult to interpret, 

 and probably the best explanation suggested is that 

 put forward by M. Gosselin. This surgeon believes 

 that at the time of the injury the lungs are suddenly 

 filled and distended with air by a full inspiration, 

 and that the air, prevented from escaping by occlusion 

 of the larynx, thus becomes pent up in the pulmonary 

 tissue, and the lung not being able to recede from 

 the superincumbent pressure, its structure necessarily 

 gives way. 



Owing to the fineness of its capillaries, and to the 

 fact that all venous blood returned to the heart must 

 pass through the lungs before it can reach other parts 

 of the body, it follows that pysemic and other secondary 

 deposits are more commonly met with in the lung 

 than in any other of the viscera. 



The trachea divides opposite the junction of the 

 manubrium and gladiolus in front, and the interval 

 between the third and fourth dorsal spines behind 

 (Fig. 33). 



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 esca-ped, 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 



