Thoracic Aneurism. 157 



Examining the above in detail we have : 



1. Pain. This may be due to the stretching of the 

 aorta plexus of nerves supplying this vessel, or to the 

 pressure of the aneurism on neighboring bones, viz., on 

 the sternum, ribs or vertebrae. The pain is subject to ex- 

 acerbations, due to increased blood pressure the result of 

 exertion or of excitement of any kind, etc. Occasionally, 

 the pain, like that of angina pectoris, may be referred to 

 other regions, such as down the arm, etc. In this case, 

 i.e., when the arm is affected, the reflex path is through 

 the ganglia of the sympathetic, especially the first thoracic 

 ganglia, to the first dorsal nerve, and thence to the brach- 

 ial plexus. Again, the pain may be felt very severely in 

 the back or in the front of the chest ; here it is due to the 

 connection of the thoracic ganglia with the intercostals. 



2. Oesophagus. The result of pressure on this 

 tube is the production of dysphagia, and this is especially 

 liable to occur, if the portion of the aorta dilated be the 

 left end of the arch, since, as already mentioned, this part 

 is in intimate association with the oesophagus, trachea, 

 thoracic duct and the pneumogastric nerve, about the level 

 of the fourth and fifth dorsal vertebrae. 



According to Bryant, these points are situated about 

 ten and one-eighth and eleven inches, respectively, from 

 the superior incisor teeth, and, of the remaining vertebrae, 

 the first dorsal is eight inches ; the second, eight and five- 

 eighths ; the third, nine and three-eighths, and the tenth, 

 fifteen inches from these teeth. Great care should be ex- 

 ercised by the surgeon in examining any oesophageal ob- 

 struction with a sound, since there is always a possibility 

 that the cause of the obstruction may be an aneurism, sep- 

 arated from the bougie by the comparatively thin wall of 

 the oesophagus only. 3. Pressure on the trachea or bron- 

 chi causes dyspnoea with the production, on auscultation, 



