THE ALIMENTARY CANAL AND ITS APPENDAGES. 337 



just after a moderate meal it is about ten inches long, by five 

 wide at its broadest part. 



Structure of the Stomach. This organ has four coats, 

 known successively from without in as the serous, the mus- 

 cular, the submucous, and the mucous. The swous coat is 

 formed by a reflection of the peritoneum, a double fold of 

 which slings the stomach : after separating to envelop it the 

 two layers again unite and, hanging down beyond it, form the 

 great omentum. The muscular coat t (Fig. 59) consists of 

 unstriped muscular tissue arranged in three layers: an outer, 

 longitudinal, most developed about the curvatures; a circu- 

 lar, evenly spread over the whole organ, except around the 

 pyloric orifice where it forms a thick ring; and an inner, 

 oblique and very incomplete, radiating from the cardiac 

 orifice. The submucous coat is made up of lax areolar tissue 

 and binds loosFlTTlie mucous coat to the muscular. The 

 mucous coat is a moist pink membrane which is inelastic, and 

 rar^e-etttrtrfli to line the stomach evenly when it is fully dis- 

 tended. Accordingly, when the organ is empty and shrunken, 

 this coat is thrown into folds, which disappear when the organ 

 is distended. During digestion the arteries supplying the 

 stomach become dilated and, its capillaries being gorged, its 

 mucous membrane is then much redder than during hunger. 



The blood-vessels of the stomach run to it between the 

 folds of peritoneum which sling it. After giving off a few 

 branches to the outer layers, most of the arteries break up 

 into small branches in the submucous coat, from which twigs 

 proceed to supply the close capillary network of the mucous 

 membrane. 



The nerves of the stomach are chiefly derived from the 

 Tmeumoffastrica. In the lower part of the thorax these nerves 

 consist mainly of nonmedullated. fibres, and lie on the sides_ 

 of the gullet, across which they interchangej^bres by means 

 of several branches. On entering the'abdomen the left pneu- 

 mogastric passes to the ventral side of the..^JQinacfa., in which 

 ft ends: the right supplies the dorsal side of the stomach, but 

 a considerable portion of it passes on to enter the solarjrtexus, 

 which lies behind the stomach and ^contains several large 

 ganglia. The sympathetic also supplies gastric nerves which 

 mainly go to the blood-vessels. In the muscular coat of the 

 stomach are many nerve-cells. 



Histology of the Gastric Mucous Membrane. Examina- 



