GASTEIC ULCEB. 353 



position of the left bronchus. The subsequent formation of a 

 mediastinal abscess or ulceration into the aorta, pericardium, 

 left bronchus, trachea, pleura or lung tissue are sufficiently 

 explained by the relations of the gullet to these structures. 



Rupture of the oesophagus is rare and is practically limited to 

 the lower third of the tube. The rent, which is usually longi- 

 tudinal, may open directly or indirectly into either pleural 

 cavity, causing pneumothorax. Mediastinal emphysema, sup- 

 puration or haemorrhage may also occur. The lower part of the 

 gullet differs from the upper in that it consists of involuntary 

 muscular fibres and is firmly fixed to the diaphragm, also simple 

 ulceration usually occurs in the lower third of the tube. All 

 these factors may favour rupture during the act of vomiting. 



Idiopathic dilatation of the oesophagus has been variously 

 attributed to pressure by a dilated aorta or hypertrophied heart 

 or spasm of the cardiac orifice. It may, however, occur without 

 evidence of the presence of any of these conditions, and is 

 possibly due to paralysis of the longitudinal muscular fibres and 

 consequent inability to open the cardiac sphincter. 



DISEASES OF THE STOMACH. 



Gastric Ulcer. Since quite two-thirds of the stomach lie under 

 cover of the liver and left costal arch only a small portion of the 

 stomach, which includes the pylorus, can be palpated. The area 

 of superficial tenderness may afford some indication of the position 

 of the ulcer. The stomach is innervated from the seventh, eighth 

 and ninth dorsal segments. The seventh segment supplies the 

 cardiac end and is distributed to a skin field which includes the 

 ensiform region, extending round to the back across a spot oppo- 

 site the eighth and ninth dorsal spines, below the lower angle of 

 the scapula. Superficial tenderness may be found in both these 

 regions when the cardia is the site of ulceration. The ninth 

 segment innervates the region of the umbilicus. The eighth 

 segment is intermediate in position. When this segment is 

 involved a tender spot may be found in front or in the infra- 

 axillary region. As a general rule the nearer the superficial 



C.A.A. 23 



