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, a7id 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, 

 hut leaving the right side, or that portion sittiated 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)i 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.^ 



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



' Although the matter arrived at is essentially the same as 

 described above, dissections I have made of the stomachal coats 

 lead me to put their description in somewhat different words : 

 (i) A Superficial Plane. — This is evidently a continuation of the 

 longitudinal muscular layer of the oesophagus. It radiates obliquely 

 over the left sac, which it completely covers. In the lesser 

 curvature its fibres become somewhat abruptly lost, while the 

 greater curvature retains them to the entire envelopment of the 

 underneath surface of the right sac, on whose upper surface they 



