Thoracic Aneurism. 163 



gastric, the cardiac and the phrenic nerves, the left in- 

 nominate vein and the sternum; behind, would be the 

 oesophagus, the sympathetic nerves and the vertebral col- 

 umn, while, internally, and behind are the oesophagus, 

 trachea and the thoracic duct. 



Operations on the Mediastinum. The struc- 

 tures of the mediastinum, on which operative work is 

 sometimes necessary, are : The oesophagus and the trachea. 

 Foreign bodies not infrequently lodge in these tubes and 

 occasionally necessitate, for their removal, an incision 

 through the walls of the tubes. In the. case of the oeso- 

 phagus, in addition to the necessity of operation for the 

 removal of a foreign body, it is occasionally necessary to 

 open the canal for the purpose of dividing a stricture, or 

 removing a localized tumor of its walls. Should the for- 

 eign body be irregular and jagged, pushing it down, or 

 extracting it by the mouth, would not be allowable, since, 

 extensive injury might result from its removal in this 

 manner, hence it would be advisable to expose it by an 

 external incision at the lower part of the neck, and, gener- 

 ally on the left side. This incision may be adopted for 

 the employment of instruments to dilate a stricture, or, to 

 remove a tumor, but, should the foreign body, or the 

 stricture be situated lower down than the aortic arch, 

 then, an attempt would have to be made from below 

 through the stomach, since the finger can reach only as 

 low down as the level of the arch of the aorta when in- 

 serted into the usual wound for oesophagotomy in the 

 neck. After a preliminary gastrotomy, the ringer, insert- 

 ed through the cardiac orifice, may feel the foreign body 

 and assist in its removal, or instruments may be employed 

 to push it through into the stomach. When the operation 

 is to divide a stricture it is termed retrograde dilatation. 

 In Abbe's method, a heavy braided piece of silk is drawn 



