EMPHYSEMA OF THE LUNG. 121 



lung is complicated with deformity of the costal cartilages, to which 

 Freund first called attention in his valuable work. This deformity con- 

 sists in a hypertrophy, by which each cartilage gains in volume in all 

 directions simultaneously, assuming a remarkably firm, brittle, rigid 

 character. By elongation of the costal cartilages, not only is the ster- 

 num driven farther from the ends of the bony ribs and pushed forward, 

 but the ribs are moved upward and outward, and twisted upon their 

 long axes in the same manner as they are turned about their axes dur- 

 ing inspiration by the traction of the inspiratory muscles. As, however, 

 the hypertrophied costal cartilages have become rigid, the thorax can- 

 not return to its expiratory state, from this inspiratory ectasis, which 

 may much exceed the largest degree of inspiratory expansion which the 

 thorax can ever normally attain. A condition arises which Freund very 

 aptly calls " rigid dilatation of the thorax." I beh'eve that Freund goes 

 too far in assuming the alterations of the costal cartilage to be the 

 primary disease, and the structural change of the lung to be secondary. 

 In a very few cases at most, principally cases of inherited emphysema, 

 does this sort of genetic connection seem somewhat probable. 



In the majority of instances, as before said, it would seem to be 

 only a complication. True, it is not an accidental one. It would rather 

 appear that the same evils which effect the structural changes in the 

 lungs also cause hypertrophy and degeneration of the costal cartilages. 

 From its analogy to hypertrophy, and to alteration of other bodies, par- 

 ticularly to degeneration of the arterial walls, which is of inflammatory 

 origin, or at least depends upon processes related to inflammation, we 

 may suppose that this alteration of the costal cartilages is a result of 

 repeated injury from distention and straining. When emphysema arises 

 from forced inspiration, or from forced expiration, with closure of the 

 glottis, from violent coughing, or through playing upon wind-instru- 

 ments, the ribs also are expanded and strained, and the structural changes 

 mentioned above develop in them in consequence of this irritation. If 

 forced inspiration have produced the emphysema, the alteration of the 

 costal cartilage is general. When forced expiration with constriction 

 of the glottis is its cause, the alteration is confined to the upper ribs. 

 Finally, costal hypertrophy and rigid dilatation of the chest, as a rule, 

 do not take place at all where the emphysema does not appear until 

 late in life, after the cartilages have become ossified. The importance 

 of the part played by this rigid thoracic dilatation in many cases of 

 emphysema is shown, among other ways, in our not unfrequently ob- 

 serving patients, whose dyspnoea decreases when they lie upon their 

 bellies, and thereby compress the thorax ; and others whose sufferings 

 are greatly relieved by exerting a lateral pressure upon the lower part 

 of the chest. In such patients I have frequently been able to observe, 



