THE STOMACH. 27 



and dried state, and then presents a sort of septum not unlike 

 the form of the iris. Around the external periphery of this 

 ring, the circular muscular fibres have a sudden augmentation 

 of number, which gives them, when viewed from the duodenum, 

 the appearance of a distinct circular muscle, occasionally called 

 the muscle of the pylorus, but it does not exist in a state so se- 

 parate as this name indicates. The opening of the valve is ge- 

 nerally circular, but sometimes ovoidal, and if is sometimes to 

 one side. 



It is very common to find the stomach divided as it were into 

 two compartments, by a contraction of its middle, resembling 

 that of an hour glass. It is said that this occurs habitually 

 during digestion; in my personal observations, however, I have 

 seen the stomach more frequently in this state when it contained 

 nothing, not even air, than when articles of aliment were in it. 



The stomach is extremely vascular. Its arteries, being 

 branches of the Cceliac, are the Gastric, the Right, and the Left 

 Gastro-Epiploic, and tlie Vasa Brevia. The first goes along its 

 lesser curvature, the second and the third along its greater cur- 

 vature, and the last, from four to six in number, go to its great 

 cul-de-sac. They all approach it between the lamina? of its 

 omenta, and undergo many divisions and subdivisions in the 

 cellular coat; they at length terminate by forming a very fine 

 and delicate vascular arrangement in the substance of the mu- 

 cous membrane, and when successfully injected give to the 

 latter a thorough tinge of red. The veins follow the course of 

 the arteries, and like them have frequent anastomoses, but are 

 larger; they terminate either directly or indirectly in the trunk 

 of the Vena Portarum. 



The nerves of the stomach come from the Par Vagum, and 

 from the semi-lunar ganglions of the Sympathetics. 



Its lymphatics arise from both the external and the internal 

 surface, and their trunks having to pass first of all to the lym- 

 phatic glands situated along the curvatures, afterwards empty 

 into the thoracic duct. 



