SURGICAL ANATOMY OF THE ABDOMEN 9 



The cardiac extremity of the oesophagus is very thick, 

 the opening into the stomach small and filled with the 

 folds of mucous membrane lining it, and the cardia 

 itself surrounded by muscular fasciculi producing a 

 powerful occlusion of the orifice. It is owing to these 

 causes that the horse is usually unable to vomit. 



From careful dissection I have found the following 

 to be the arrangement of the cardiac fibres : Around the 

 cardia and left extremity of the stomach are three layers 

 of muscular fibres — (i) the external, running towards the 

 pylorus and also over the left cul-de-sac ; (2) the middle, 

 running round the cardia, being a continuation of the 

 circular fibres of the oesophagus, and very thick at the 

 portion situated in the lesser curvature ; (3) the internal, 

 running in the direction of the long axis of the organ, 

 passing as a loop round the left side of the cardia, 

 but leaving the right side, or that portion situated within the 

 lesser curvature, without fibres. It is this layer, in conjunc- 

 tion with the middle layer, which forms the so-called 

 sphincter, for, owing to the arrangement of the fibres, 

 the cardia is compressed on the left towards the right by 

 the (looped fibres of the)^ internal layer, and on the 

 right towards the left by the middle layer. The pyloric 

 extremity of the stomach is supplied with a sphincter, 

 the so-called pyloric ring. 



We believe that, in addition to the resistance offered 

 to vomition by the cardia, the contraction of the 

 CESophagus (at least, the posterior half of it) materially 

 assists in preventing anything passing along it in the 

 reverse direction, for we always find that where dilatation 

 of the cardia has occurred so as to allow vomition the 

 oesophagus is likewise dilated and its walls are flaccid. 



On examining a stomach and oesophagus after death, 

 ' The insertion in brackets is mine. — H. C. R. 



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