236 Dilatation of the Esophagus. 



(see page 232). Ectasias of this type extend over a large 

 portion of the esox)liagus. 



Schiiiiiuel saw an ectasia in a liorse with profound paralysis of the recurrent 

 nerve which was 58 cm. long. He considered the affection to be due to gastrophilus 

 larvje which had located there while the animal was still a foal. 



Basing his views on a carefully investigated case, Kelling claLins that dilata- 

 tion without stenosis is due to atrophy of the longitudinal muscle fibers of the 

 esophagus, this in its turn being caused by degeneration of fibers of the pneunio- 

 gastric nerve following infection. 



Diverticnla of the esophagus are formed rarely, and then 

 in the following manner: A uniform dilatation has developed 

 in consequence of esophageal stenosis or obstruction, and the 

 accumulated masses of food have exerted pressure upon the 

 esophageal wall; a diastasis has consequently been produced 

 in the muscularis and a prolapse into the cleft has been formed 

 by the mucosa, the latter again pushes against the connective 

 tissue which yields and a diverticulum is now formed in the 

 region of the dilation. More commonly the mucosa and the 

 muscularis are injured by rough or pointed foreign bodies and 

 the non-elastic cicatricial tissue which forms is subsequently 

 dilated by morsels of food (socalled false diverticula). 

 Genuine diverticula, which must always include the muscularis, 

 are in some cases produced by pressure from the lumen 

 (diverticulum per pulsionem ortum) by wedged-in foreign 

 bodies, feed material, or neoplasms of the esophagus, or more 

 rarely by traction upon the external surface l)y adhering heavy 

 tumors, by contracting diseased lymph glands, between the 

 esophagus and the trachea or a bronchus, or l)y the contracting 

 cicatricial tissue following an abscess (diverticulum per trac- 

 tionem ortum). 



In exceptional cases the diverticules are formed without 

 any obvious cause. In horses they may also be due to small, 

 long clefts with a giving way of muscle bundles, as is seen in 

 otherwise perfectly healthy animals (Kitt). 



Storch, in connection with a case, gives it as his opinion that diverticula may 

 1)6 congenital and may stand in some relation to the second bronchial cleft, so 

 that a diverticulum might be an internal incomplete bronchial cleft. Johne had 

 previously pointed out such an explanation as possible. 



Diverticula are sometimes short, sometimes they run as 

 long parallel tubes above or laterally to the esophagus with 

 which they may communicate by a wide opening or ))v a narrow 

 cleft. 



Pathogenesis. Food collects in the ectatic esophagus or 

 in the diverticulum at each feeding; water likewise collects 

 if the diverticulum is directed downwards. This finally becomes 

 filled completely and then compresses the esophagus so that 

 it ])roduces stenosis or even complete obstruction. The morsels 

 which now follow, either pass w^ith difficulty or they become 



