LOWER ABDOMINAL VISCERA. 645 



lowest nerve sending fibres to the splanchnic is, with an anterior arrange- 

 ment of nerves, the first lumbar, and with a posterior arrangement of 

 nerves, the second lumbar. 



It will be seen that the conclusions thus reached agree very closely with 

 the experimental results of Francois-Franck and Hallion, on the vasomotor 

 supply of the liver, pancreas, and intestine in the dog. The nerves which 

 had a marked effect were the sixth thoracic to the first lumbar ; the second 

 lumbar had a slight effect — probably there would have been none if the 

 arrangement of nerves had been anterior; the fifth thoracic had an effect 

 sometimes, and the fourth very rarely. 



On the other hand, the third thoracic nerve is stated by Bulgak and by 

 Schiifer and Moore to have an effect on the spleen ; the third and fourth 

 lumbar are said by Bradford to cause contraction of the kidney vessels ; and 

 the third, fourth, and fifth lumbar nerves are said by Bunch to cause con- 

 traction or inhibition of the small intestine. But in all cases the effects were 

 slight, and in none were the nerve fibres producing them shown to pass by the 

 splanchnics. With regard to fibres from the third and fourth lumbar nerves, 

 it is possible that some might pass to the intestine, etc., by way of the 

 inferior mesenteric ganglia, but I think this is very unlikely. It is also to be 

 borne in mind that in the dog, so far as is known, the fifth lumbar nerve never 

 has a white ramus, and that sometimes (anterior plexus) the fourth lumbar 

 nerve also has no white ramus. 



We have said that the cceliac artery, the superior mesenteric artery, and 

 the renal artery receive their nerves in large part, but not altogether, from 

 separate ganglia. A comparison of the facts we have learnt with regard to 

 the connections of the vertebral ganglia, does not give us any sure guidance as 

 to the connection of the several pre-vertebral ganglia, but it suggests that a 

 more anterior set of nerves will pass to the cceliac than to the superior 

 mesenteric ganglia, and to the superior mesenteric than to the renal ganglia, 

 and that these sets will overlap considerably. It suggests further that, as 

 regards the connection of the spinal nerves with the several arteries, there 

 will be an additional overlap, due to fibres from one ganglion passing to more 

 than one artery. 



It is not worth while to discuss this matter at present, since there are 

 practically no anatomical or histological data, and the experimental data are 

 insufficient. It may, however, be pointed out that the spinal nerves which 

 have the maximum effect on the spleen are the mid-thoracic (Schafer and 

 Moore), whilst those which have the maximum effect upon the vessels of the 

 intestine (Francois-Franck and Hallion) and of the kidney (Bradford) are the 

 lower thoracic. It may be expected that further investigation will show 

 that the maximum effect on the intestine is obtained from a more anterior 

 set of nerves than that which gives the maximum effect on the kidney. 



Lower abdominal viscera.— The sympathetic nerve strands which 

 supply the lower abdominal and pelvic viscera, are three or four on each 

 side. Since these strands correspond to the splanchnic nerves, we may 

 call them the inferior splanchnic nerves. 1 



The inferior splanchnic nerves run to the inferior mesenteric ganglia. 

 In the cat, rabbit, and many other animals, there are two on each side, 

 one above and one below the inferior mesenteric artery, connected with 

 one another by nerve strands. As the connecting strands are often 

 short, the whole group is often spoken of as a single ganglion, the 

 inferior mesenteric ganglion. 



1 They have also been called the rami efferentes of, and the spinal branches to, the 

 inferior mesenteric "anidion. 



