3t)2 GENERAL ANATOMY. 



vian region, a deep inspiration sometimes draws air into it, 

 which is sucked into the right cavity of the heart, and which, 

 by stopping the circulation, produces sudden death. 



451. In youth the venous system is less extensive, in pro- 

 portion to the arterial system, than in the adult age; its rela- 

 tive capacity continues to augment in old age. The parietes 

 of the veins offer small observable changes; their senile ossi- 

 fication is extremely rare. 



452. The morbid alterations of the veins,* have been less 

 studied than those of the arteries. 



The inflammation of the veins or phlebites, is an affection 

 to which Hunter has been one of the first to draw the atten- 

 tion of the profession. It ordinarily occupies a considerable 

 extent of the veins, and generally extends towards the heart. 

 It often gives rise to the formation of pus, and at other times 

 to that of plastic matter in the cavity of the vein, around it, 

 and even in its own thickness. It mostly depends on mecha- 

 nical lesions. 



453. Wounds of the veins, considered under an anatomical 

 point of view, present some analogy with those of the arteries; 

 but, in whatever mode they are inflicted, they are much more 

 easily followed by ulceration or extension and often suppura- 

 tive inflammation than those of the arteries, and they unite 

 with more difficulty. After puncture or incision, there re- 

 mains between the edges a space filled by a new membrane; 

 the ligature does not first determine the division of the inner 

 membrane and quickly its adhesion, but this membrane is at 

 first only plaited, and is divided but slowly in order to unite 

 feebly. 



454. Accidental productions are more rare in the parietes 

 of the veins than in those of the arteries. The cartilaginous, 

 or an analogous thickening, occurs however sometimes in the 

 parietes of the veins which are obliterated; Morgagni ob- 

 served it once in the vena cava. Ossification is extremely 

 rare in the veins. Dr. Baillie has seen it once to occur in the 

 vena cava inferior near the iliacs, and Dr. Macartney once 



* Hodgson* op. cit. B. Travers, Surgical Essays, part first. 



