458 THE CIRCULATORY SYSTEM. 



The wound in the artery may heal and the effused blood be absorbed ; 

 or it may become the seat of secondary inflammatory processes. 



Finall;/ a wall of fibrous tissue may be formed, while the wound of 

 the artery remains open, so that there is an aneurismal sac through 

 which the blood is constantly pouring. This is called a false aneurism. 



Aneurismal Varix : Varicose Aneurism. If an artery be wounded, and 

 at the same time the vein which accompanies it, we have as the result the 

 conditions called aneurismal varix and varicose aneurism. In aueurismal 

 varix the artery and vein become adherent at the seat of injury, so that 

 the arterial blood passes directly into the vein. There is a smooth, 

 rounded opening between the two vessels, the vein is dilated into a sac, 

 and the veins emptying into it are dilated and tortuous. In varicose 

 aneurism the artery and vein do not communicate directly, but a false 

 aueurismal sac is formed between the vessels, into which the blood is 

 poured before passing into the vein. Varicose aneurism may also be 

 formed by the spontaneous rupture of an aneurism into a vein. The 

 aneurism presses against the vein, becomes adherent, and finally rup- 

 tures into it. This condition has been observed between the aorta and 

 pulmonary artery ; the aorta and inferior and superior vena cava ; the 

 popliteal artery and vein; the femoral artery and vein; the splenic 

 artery and vena azygos ; the internal carotid and sinus cavernosus. 



Cirsoid Aneurism is one formed by the dilatation and lengthening of 

 large or small arteries or arterial tracts. The walls of the arteries are 

 thinned, the vessels are tortuous and in places sacculated. These 

 changes are most frequent in small arteries, especially the temporal and 

 occipital. They involve the trunk of the vessel and its branches, or 

 may extend to the capillaries and small veins. They form larger or 

 smaller tumors beneath the skin. 



ANEURISMS OF THE DIFFERENT ARTERIES. 



The aorta may be dilated over its entire length, or there may be diffuse 

 or circumscribed dilatations at any portion of its course ; or there may 

 be several aneurisms, situated at different points. The ascending por- 

 tion of the arch of the aorta may be uniformly dilated in a fusiform 

 shape (Fig. 255), or there may be circumscribed dilatations on its an- 

 terior wall, or, more rarely, on its posterior wall. The sacculated aneu- 

 risms vary in size and may rupture within the pericardium ; or they may 

 form a cavity in the upper part of the ventricular septum and commu- 

 nicate by openings into the pulmonary artery and left ventricle ; or they 

 may dilate downward between the visceral and parietal pericardium, in 

 front of the heart, pushing that organ backward. They may perforate 

 into the right or left auricle or right ventricle, the superior vena cava, 

 or the pulmonary artery ; or they may reach a large size, press on and 

 erode the right side of the sternum and adjoining ribs, project under the 

 skin, and even rupture externally. 1 



1 For extension of aortic aneurism into the heart and dissecting aneurisms of the 

 heart see Ilektoen, Trans. Assn. Am. Phys., vol. xvi., p. 127. 



