238 INFLUENCE OF NERVES ON THE INTESTINE. 



inflammation), all act upon the intestine, either from without or from within. Induction- 

 shocks applied to a loop of intestine in a hernial sac cause lively peristalsis in the hernia. The 

 intestinal movements are favoured by heat. 



4. The continued application of strong stimuli causes the dysperistalsis to give 

 place to rest, owing to over-stimulation, which may be called " intestinal paresis," 

 or exhaustion. 



This condition is absolutely different from the passive condition of the intestine in aperistalsis. 

 Continued congestion of the intestinal blood-vessels ultimately causes intestinal paralysis, e.g., 

 when transfusion of foreign blood causes coagulation within these vessels. Filling the blood- 

 vessels with "indifferent" fluids, after the peristalsis has been previously brought about by 

 compressing the aorta, also causes cessation of the movements (0. Nasse). The movements 

 cease when the intestines are cooled to 19 C. (Hovwath), while severe inflammation of the 

 intestine has a similar effect. Under favourable circumstances, the intestine may recover from 

 this condition. Arterial blood admitted into the vessels of the exhausted intestine causes 

 peristalsis, which at first is more vigorous than normal. 



5. The continued application of strong stimuli causes complete paralysis of the 

 intestine, such as occurs after violent peritonitis, or inflammation of the muscu- 

 lature or mucous coat in man. In this condition, the intestine is greatly distended, 

 as the paralysed musculature does not offer sufficient resistance to the intestinal 

 gases which are expanded by the heat. This constitutes the condition of 

 meteorism. 



Influence of Nerves. With regard to the nerves of the intestine, stimulation of 

 the vagus increases the movements (of the small intestine), either by conducting 

 impressions to the plexus myentericus, or by causing contraction of the stomach, 

 which stimulates the intestine in a purely mechanical manner (Braam-Houekgeest). 

 The splanchnic is (1) the inhibitory nerve of the small intestine (Pfliiger), but 

 only as long as the circulation in the intestinal blood-vessels is undisturbed, and 

 the blood in the capillaries does not become venous ; when the latter condition 

 occurs, stimulation of the splanchnic increases the peristalsis. If arterial blood be 

 freely supplied, the inhibitory action continues for some time. Stimulation of the 

 origin of the splanchnics, of the spinal cord in the dorsal region (under the same 

 conditions), and even when general tetanus has been produced by the administration 

 of strychnia, causes an inhibitory effect. It is inferred that the splanchnic contains 

 (2) inhibitory fibres, which are easily exhausted by a venous condition of the 

 blood, and also motor fibres, which remain excitable for a longer time, because after 

 death, stimulation of the splanchnics always causes peristalsis, just like stimulation 

 of the vagus. (3) It is the vaso-motor nerve of the intestinal blood-vessels, so that 

 it governs the largest vascular area in the body. When it is stimulated, all the 

 vessels of the intestine which contain muscular fibres in their walls contract ; when 

 it is divided, they dilate. In the latter case, a large amount of blood accumulates 

 within the blood-vessels of the abdomen, so that there is anaemia of the other parts 

 of the body, which may be so great as to cause death owing to the deficient supply 

 of blood to the medulla oblongata. (4) It is the sensory nerve of the intestine, 

 and, under certain circumstances, it may give rise to very painful sensations. 



As stimulation of the splanchnic contracts the blood-vessels, von Basch has raised the ques- 

 tion whether the intestine does not come to rest, owing to the want of the blood, which acts as 

 a stimulus. But, when a weak stimulus is applied to the splanchnic, the intestine ceases to 

 move before the blood-vessels contract (van Braam-Houckgeest) ; it would therefore seem that 

 the stimulation diminishes the excitability of the plexus myentericus. According to Engel- 

 maun and v. Brakel, the peristaltic movement is chiefly propagated by direct muscular con- 

 duction, as in the heart and ureter, without the intervention of any nerve-fibres. 



[Effect of Nerves on the Rectum. The nervi erigentes, when stimulated, cause the longi- 

 tudinal muscular fibres of the rectum to contract, while the circular muscular fibres are supplied 

 by the hypogastric nerves. Stimulation of the latter nerves also exerts an inhibitory effect on 

 the longitudinal muscles. Stimulation of the nervi erigentes inhibits not only the spontaneous 

 movements of the circular fibres of the rectum, but also those movements excited by stimulation 

 of the hypogastric nerves (Fellner).] 



[Artificial Circulation in the Intestine. Ludwig and Salvioli excised a loop of intestine 



