SECTION III 



DISEASES OF THE GEEAT VESSELS. 



CHAPTER I. 



INFLAMMATION OF THE COATS OF THE AORTA. 



ETIOLOGY. Inflammation of each of the three tissues of the aorta, 

 the adventitia, the media, and the intima, is best studied by itself, just 

 as we have already successively discussed pericarditis, myocarditis, and 

 endocarditis. 



Acute inflammation of the tunica adventitia is rare, and hardly ever 

 occurs, excepting when inflammation or ulceration of the lymphatic 

 glands, the oesophagus, the trachea, or other neighboring organ, ex- 

 tends into the aorta. Chronic inflammation is far more common ; but 

 neither is it primary, being allied almost always to pericarditis and at- 

 tacking the root of the aorta ; or else to endarteritis, when its action 

 may be very extensively diffused. 



The tunica media often takes part in inflammation of the adventitia. 

 In chronic inflammation of the ultima, too, the media is almost always 

 diseased, but is not often inflamed. It is much more commonly the 

 seat of simple atrophy or of fatty degeneration. 



From Vircliovfs point of view, chronic inflammation of the internal 

 coat of the arteries is to be regarded as one of the most frequent of 

 diseases. The reason for classing the gelatinous and semicartilaginous 

 thickening of the inner arterial tunic (see below), which forms the in- 

 cipient stage of ossification and atheroma of the arterial walls, among 

 the parenchymatous inflammations, is due to the fact that, in this dis- 

 ease, we undoubtedly have to do with an active process, with genera- 

 tion of cells, and that in many cases it can be shown that these nutri- 

 tive disturbances owe their origin to certain irritants which iiave acted 

 upon the tunics ; as, undue strain, or distention (see pathogeny of 

 endocarditis). In other cases, indeed, it cannot be proved that the 

 arteries have been subjected to special irritants; as, however, the 



