ABDOMINAL CAVITY 



353 



Structure of the Stomach. The coats of the stomach are 

 five in number, viz. : 



1. Peritoneal, or serous. 



2. Subserous. 



3. Muscular. 



4. Submucous. 



5. Mucous. 



The serous coat, consisting of the peritoneal membrane, 

 can be stripped off best by the fingers. The subserous coat 

 is composed of a little 

 areolar tissue which inter- 

 venes between the muscular 

 and serous strata. The 

 branches of the two vagi 

 nerves can now be followed, 

 as they spread out upon 

 the two surfaces of the 

 stomach. 



The muscular coat of the 

 stomach consists of involun- 

 tary muscle fibres which are 

 arranged in three strata; 

 an external longitudinal 

 stratum, an intermediate cir- 

 cular stratum, and an internal 

 oblique stratum. The ex- 

 ternal longitudinal stratum 

 is continuous above with 

 the longitudinal fibres of 

 the oesophagus and below 

 with the longitudinal fibres 

 of the duodenum. It is best marked along the lesser curva- 

 ture, and in the region of the pylorus, where it takes part in the 

 formation of the pyloric sphincter ; on the greater curvature, 

 on the fundus, and on the surfaces of the stomach it is 

 extremely thin. Nevertheless it is the only muscular stratum 

 which forms a continuous and unbroken sheet. The inter- 

 mediate circular stratum commences as a series of U-shaped 

 loops, which only partially encircle the body of the stomach. 

 At the upper part of the lesser curvature they are continuous 

 with the superficial circular fibres of the oesophagus. Thence 

 they extend over both surfaces of the body of the stomach 

 but fail to reach the great curvature, and they are absent over 



VOL. II 23 



FIG. 163. Dissection of the three layers 

 of Muscular Fibres in the Wall of the 

 Stomach. 



