786 



PHYSIOLOGY 



the musculature of the fundus or body of the stomach, the most 

 usual effect is an inhibition during stimulation of the vagus succeeded 

 by an augmented tonus immediately the stimulus is removed. If 

 the vagus be excited a number of times the tonus of the muscular 

 wall augments with each stimulus. On the pyloric portion stimula- 

 tion of the vagus also causes inhibition, followed by contraction. 



LSyCh 



FIG. 337. Distribution of the vagus in the abdomen of the dog. 



(M. H. NAYLOB.) 



RV, LV, right and left vagi. The right vagus runs behind the oesophagus 

 (Oe) and stomach (St), and in those places is represented by a discontinuous 

 line. Cb, connecting branch between right and left vagi ; P, pancreas ; Dd, 

 duodenum ; FDJ, flexura duodeno-jejunalis ; I, I, 1, intestine ; L, liver ; 

 K, kidney ; A, suprarenal capsule ; RG, LG, right and left crura of diaphragm ; 

 L.Sy.Ch, left sympathetic chain; 12 D, 13 D, twelfth and thirteenth dorsal 

 ganglia ; 3 L, third lumbar ganglion ; G.Sp.N, L.Sp.N, great and small 

 splanchnic nerves ; S.G, left semilunar and superior mesenteric ganglia ; 

 D.A, dorsal aorta. 



The inhibition may, however, be very short and in rare cases altogether 

 absent, so that during the excitation this inhibition is followed by 

 a series of large rhythmic contractions. The prevailing motor effect 

 of the vagus therefore is in the fundus increased tonus, in the pyloric 



