SYMPATHETIC NERVE. 



4C5 



Longet, on repeating the experiments of Valen- 

 tin, failed to observe any contractions, and 

 concludes that Valentin must have irritated 

 the pneumogastric as well as the sympathetic. 

 It is only (according to Longet) when the 

 pneumogastric or spinal nerves are irritated, 

 that such contractions ensue ; and, moreover, 

 section of the eighth pair is attended by com- 

 plete paralysis of the oesophagus. 



Stomach. The stomach, like the oesopha- 

 gus, is supplied by branches of the pneumo- 

 gastric and sympathetic. Irritation of the 

 former is almost always followed by con- 

 tractions in this organ. Irritation of the 

 splanchnic nerves, or of the semilunar gan- 

 glion, according to Longet*, produces no 

 such effect. Valentin, on the other hand, 

 found that stimulus applied to the main cord 

 of the sympathetic in the neck, or to the in- 

 ferior thoracic ganglia, in the rabbit, gives 

 rise to contractions in this organ. Voikmannf 

 has also found that when the stimulus of the 

 electro-magnetic rotation apparatus is applied 

 to the thoracic portion of the sympathetic in 

 the cat it gives rise to powerful peristaltic 

 movements in the stomach. He also observed 

 still more lively contractions excited in the 

 stomach of a young dog when the same sti- 

 mulus as in the previous experiment was 

 applied to the sympathetic cord in the thorax, 

 or to the greater or smaller splanchnic nerves 

 before they enter the semilunar ganglion. It 

 would seem, therefore, that, besides the motor 

 filaments which are sent to the stomach by 

 the pneumogastric, it also receives others 

 through the medium of the sympathetic. 



As regards the movements of the small 

 intestine, &c., it is almost invariably excited 

 to contraction by irritation of the splanchnic 

 nerves or semilunar ganglion. After the 

 movements produced in the intestine by the 

 stimulus of the air, acting upon them when 

 the cavity of the abdomen is laid open, have 

 subsided, contractions extending over the 

 greater part of the gut may still be produced, 

 as was first shown by Miiller, by application of 

 chemical irritants, such as potash, to the solar 

 plexus. According to Valentin, the move- 

 ments produced by irritation of the splanchnic 

 nerves are chiefly confined to the duodenum 

 and upper part of the jejunum, while irritation 

 of the solar plexus, on the other hand, is fol- 

 lowed by contractions which extend over the 

 whole of the small intestine. Irritation of the 

 sympathetic cord in the thorax as high up as 

 the fifth or sixth ganglion, and also in the lum- 

 bar region, gives rise, according to Valentin, 

 to distinct contractions in the small intestine, 

 while stimulus applied to the lumbar and 

 sacral portions acts very energetically upon 

 the great intestine and rectum. The influence 

 of the sympathetic over the movements of the 

 intestines is also shown by the observation 

 of Valentin that when the branches which 

 pass along the mesentery are irritated, con- 

 tractions are produced in the particular por- 

 tions of the intestine to which they are dis- 



* Op. cit. p. 609. 



t Mullers Archiv. 1845, p. 414., &c. 

 Supp. 



tributed, while the rest of the gut remains 

 quite motionless. 



Budge observed that movements were ex- 

 cited in the coecum of the rabbit when the 

 trunk of the vagus-nerve in the neck was 

 stimulated by means of the electro-magnetic 

 rotation apparatus. 



As in the case of the heart, so also in 

 regard to the intestinal canal, stimuli applied 

 to the central nervous masses have been ob- 

 served to exercise a greater or less influence 

 in exciting contractions in the intestine. 

 In animals newly killed, Valentin has fre- 

 quently observed movements produced in the 

 intestines by division of the anterior and pos- 

 terior roots of the spinal nerves. In such 

 experiments, however, it is difficult to ascer- 

 tain whether the contraction be due to the 

 stimulus applied to the nerves, or whether 

 it may not be owing to the stimulus of the 

 air acting directly on the intestines them- 

 selves. The application of galvanic stimulus 

 leads to more decisive results. When, ac- 

 cording to Valentin*, the wires of the mag- 

 neto-electric apparatus are applied to the 

 corpora quadrigemina or medulla oblongata, 

 lively contractions are excited in the stomach 

 and intestine. Contractions were also pro- 

 duced in the small intestine, great intestine, 

 and rectum, by application of the same 

 stimulus to the spinal cord. In Cyprinus 

 tinea, Weber has shown that ver} T powerful 

 contractions may be excited in the stomach 

 by application of the wires of the electro- 

 magnetic rotation apparatus to the posterior 

 part of the cerebellum or to the medulla 

 oblongata. The same stimulus applied to the 

 spinal cord in the animal above mentioned, as 

 also in dogs, he observed to be followed by 

 movements in the intestinal canal. 



From the experiments of Valentin it ap- 

 pears that the movements which are excited 

 in the intestinal canal by stimulus applied to 

 the central masses of the nervous system, are 

 not produced through the medium of the 

 pneumogastric alone. In a rabbit which had 

 been bled to death, and in which the ab- 

 dominal muscles were removed without 

 injuring the peritoneum, he found, when the 

 wires of the magneto-electric apparatus were 

 inserted into the cerebellum, that very lively 

 movements ensued in the small intestine, al- 

 though the two vagi nerves had been pre- 

 viously divided in the neck. Budge, how- 

 ever, finds that it is only when the two vagi 

 nerves have been left that movements can be 

 excited in the coecum of the rabbit by appli- 

 cation of the galvanic stimulus to the medulla 

 oblongata. 



The constipation and tympanitis which 

 frequently attend diseases of the spinal cord, 

 in like manner indicate that the central 

 masses of the nervous system exercise a cer- 

 tain influence over the movements of the 

 intestinal canal. 



These movements, however, like those of 

 the heart, still continue after the brain and 

 spinal cord have been destroyed. Bidder, as 

 * Op. cit. p. 466., &c. 



H II 



