230 Anatomy Applied to Medicine and Surgery. 



turbance of the vasomotor fibres may be seen in the effect 

 of cold applied to the cutaneous nerves, and in fright, 

 grief, etc. In the former instance, i.e. , in cold, the splanch- 

 nics which supply vasomotor fibres to the intestinal blood- 

 vessels are disturbed so that dilatation results with the pos- 

 sible production of diarrhoea from the overloaded blood- 

 vessels relieving themselves, whereas, in the latter case, i.e., 

 in fright, etc., the impression acts on the vasomotor centre 

 in the medulla and constricts, through the splanchnic 

 nerves, the bloodvessels of the intestine. In the former in- 

 stance, diarrhoea results from dilatation of the intestinal 

 bloodvessels. In this instance, diarrhoea results from con- 

 striction of the intestinal bloodvessels, so we see that oppo- 

 site conditions may bring about a similar result. The ex- 

 planation of diarrhoea occurring from a constricted state 

 of the intestinal vessels is found in the presence of the car- 

 bon dioxide which would exist in the intestinal blood in 

 greater amount than normal, because of the condition of 

 local anaemia present, and since carbon dioxide is an irri- 

 tant to Auerbach's plexus, its presence in increased quan- 

 tity causes increased peristalsis, i.e., diarrhoea. 



Lastly, the inhibitory action of the splanchnic fibres 

 may be shown by the influence opium exercises on them, 

 since it stimulates the inhibitory fibres and produces con- 

 stipation. 



The effects of reflex action from the intestine may be 

 seen in the skin when urticaria results from intestinal in- 

 digestion, while cramps in the calves of the legs bear the 

 same reflex relationship to intestinal disturbance in chol- 

 era, etc., as it did to stomach disturbance, and which has 

 been referred to under gastric reflex neuroses. 



Pain in affections of the intestines, such as appendicitis, 

 obstruction of the bowels, etc., is frequently referred to 

 the region of the umbilicus, more particularly about one 



