1 62 Anatomy Applied to Medicine and Surgery. 



plicit, it would be advisable to consider the particular 

 effects following aneurism of the special parts of the ves- 

 sel, and, in addition, those resulting from dilatation of the 

 great branches of the aorta. Ascending part of the aorta. 

 When the anterior wall of this vessel is involved the an- 

 eurism will in time erode the sternum; when the inner 

 wall is affected, it will compress the pulmonary artery 

 and interfere with the passage of the venous blood to the 

 lungs. If it be on the external wall of the vessel, the 

 superior vena cava will be compressed, and, if posteriorly, 

 the bronchus, pulmonary veins and the artery going to the 

 right lung. Transverse part of the aorta. Here, if above, 

 the aneurism will press on the left innominate vein and 

 affect the large branches of the aorta ; if in front, the left 

 pneumogastric nerve, left phrenic and the left superior 

 cardiac nerve; if behind, the trachea, the deep cardiac 

 plexus, the oesophagus, the thoracic duct and the left re- 

 current laryngeal nerve ; if below, the recurrent laryngeal 

 and the left bronchus. Thoracic aorta. In front, it would 

 affect the oesophagus below, and the root of the left lung, 

 above; internally, the oesophagus and the thoracic duct; 

 posteriorly, the vertebral column, the intercostal nerves 

 and the ribs. If the aneurism involve the anterior sur- 

 face of the innominate artery, then the sternum and the 

 left innominate vein would be affected; if externally, the 

 right innominate vein and the pneumogastric nerve, 

 whereas, if the aneurism be internally and behind, then 

 the trachea would be compressed. If the left common 

 carotid be the one diseased, then the sternum and the left 

 vena innominate, in front, would be pressed upon, while 

 externally, the left pneumogastric nerve, or, behind, the 

 trachea, the oesophagus and the thoracic duct, would be 

 the main structures liable to be injured; lastly, if it be 

 the left subclavian, then, in front, would be the pneumo- 



