450 THE HUMAN BODY 



sponsible for the "fair round belly with good capon lin'd." The 

 protrusion b to the left side of the cardiac orifice, Fig. 128, is the 

 fundus. The size of the stomach varies greatly with the amount 

 of food in it; when empty it is little more than a tube; just after a 

 moderate meal it is about ten inches long, by five wide at its 

 broadest part. 



Since the cardiac end of the stomach lies immediately beneath 

 the diaphragm, which has the heart on its upper side, its over- 

 distension, due to indigestion or flatulence, may impede the action 

 of the thoracic organs, and cause feelings of oppression in the 

 chest, or palpitation of the heart. 



Structure of the Stomach. This organ has four coats, known 

 successively from without in as the serous, the muscular, the sub- 

 mucous, and the mucous. The serous 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 

 (Fig. 43) consists of unstriped muscular tissue arranged in three 

 layers: an outer, longitudinal, most developed about the curva- 

 tures; a circular, 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 

 loosely the mucous coat to the muscular. The mucous coat is a 

 moist pink membrane which is inelastic, and large enough to line 

 the stomach evenly when it is fully distended. 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 capil- 

 laries 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 belong to the autonomic system, and 

 like most other structures supplied by this system, the stomach 

 has double innervation (p. 195). The cranial autonomic fibers are 



