THE DIGESTIVE SYSTEM. 531 



In rare cases there is cylindrical dilatation of part or of the whole of 

 the O3sophagus without a stenosis or any discoverable cause. In these 

 cases the dilatation is usually greatest near the middle of the oesophagus 

 and diminishes upward and downward, so that the oesophagus has a fusi- 

 form shape. The dilatation may reach a very considerable degree, the 

 walls of the oesophagus are thickened, its mucous membrane may be 

 covered with papillary outgrowths or ulcerated. 



The Sacculated Dilatations of the oesophagus are of two kinds : those 

 due to pressure, and those due to traction. 



The dilatations due to pressure are situated in the posterior wall of 

 the pharynx, just at its junction with the oesophagus. The smaller sacs 

 are from the size of a pea to that of a hazeluut ; the larger sacs may 

 reach a large size and hang down between the oesophagus and the verte- 

 bral column, the opening into the oesophagus remaining comparatively 

 small. It is supposed that a limited area of the wall of the oesophagus 

 loses its power of resistance against the pressure exercised upon it in 

 each act of swallowing ; it then is forced outward by the pressure, and 

 so there is formed first a protrusion and then a sac. When a sac is 

 formed the food enters it, accumulates there, and the sac becomes larger 

 and larger. 



The dilatations due to traction are situated on the anterior wall of 

 the oesophagus, at a point nearly corresponding to the bifurcation of 

 the trachea. They are of funnel shape, with the small end outward. 

 Their length varies from two to twelve millimetres ; the width of the 

 opening into the oesophagus is from six to eight millimetres. 



These dilatations are due to inflammation of the parts adjoining the 

 oesophagus, especially of the bronchial nodes, followed by adhesions to 

 some part of the anterior wall of the oesophagus. These adhesions then 

 contract and draw the wall of the oesophagus outward, and in this way 

 the dilatations are formed. 



At a later time these sacs may perforate into the bronchi, the lungs, 

 the pleural cavity, the pericardium, the aorta, or pulmonary artery. ' 



STENOSIS. 



Congenital Stenosis. Besides the defects of development of the oesoph- 

 agus which are incompatible with life, there may be a congenital stenosis 

 of some part of it which causes difficulty in swallowing, but yet does not 

 destroy life. 



Compression Stenosis is not uncommon. Tumors of the neck and 

 mediastinum, and aneurisms of the aorta are the usual causes. 



Obstruction Stenosis. Foreign bodies may be lodged in the oesophagus. 

 Tumors may hang down from the pharynx into the oesophagus, or may 

 be situated in the wall of the oesophagus. Inflammation of the cesopha- 



1 For bibliography of oasophageal diverticula see Brosch, Deutsch. Arch. f. klin. 

 Med., Bd. Ixvii., p/44, 1900; also Starck, Arch. f. Verdkr., Bd. vii., 1901, p. 1. 

 For later cases see Pfaff, Trans. Assn. Am. Phys., vol. xvi., 1901, p. 656. 



