352 CLINICAL APPLIED ANATOMY. 



relation with the oesophagus in two positions, in the superior 

 mediastinum and in the posterior mediastinum just before the 

 tube traverses the diaphragm. 



The relations of- the thoracic aorta to the oesophagus vary con- 

 siderably at different levels. The transverse aorta crosses it to 

 gain its left side. The descending aorta at first lies to the 

 left, but in the lower part of the thorax the relations of the two 

 are gradually reversed, so that the oesophagus passes in front 

 and finally lies even to the left of the aorta. Of the large 

 arteries arising from the aortic arch only the left subclavian 

 comes into relation with the oesophagus. Ulceration of a growth 

 into the aorta or subclavian is rare. Occasionally the thoracic 

 duct, the azygos veins or the sympathetic chain are implicated. 

 The thoracic duct at first lies to the right, being separated from 

 the oesophagus by the aorta, higher up it lies behind and finally 

 crosses to the left as it enters the superior mediastinum. The 

 left recurrent laryngeal nerve lies between the oesophagus and 

 the transverse aorta. It may be involved here by cancer of the 

 oesophagus. 



When cancer invades the middle and lower parts of the tube the 

 mediastinal and lumbar glands become enlarged ; when the upper 

 third is involved the glands of the mediastinum and those at the 

 root of the neck become implicated. A gland which lies in the 

 posterior triangle just above the left clavicle is of great significance 

 in this respect, but the same gland may be enlarged when the malig- 

 nant disease involves the stomach, pleura or lungs. Enlarged 

 glands may actually obstruct the oesophagus at some distance from 

 a primary carcinomatous ulcer which is causing no symptoms. 



Fibrous strictures of the oesophagus may result from the 

 action of corrosive poisons. They are found at the upper or 

 lower ends as a rule. At these points the tube is narrow and 

 the passage of fluids somewhat delayed, whilst their passage 

 along the rest of the gullet is rapid. 



Foreign bodies impacted in the oesophagus tend to become 

 fixed where the tube is narrow, that is to say at either end or 

 at a point nine inches from the incisor teeth, just above the 



