96 



THE NERVOUS SYSTEM 



actually proved to contain them. It is through these afferent fibers that 

 the viscera possess that indefinite sort of touch sense which they have, 

 and their pain sensations. The afferent fibers are only few compared with 

 those which are efferent: Langley and Anderson found one- tenth of the 

 medullated axones in the hypogastric nerves to be afferent. It is by 

 these latter fibers that the phenomena of referred pain are brought 

 about. It cannot be doubted that the afferent nerves of the sympathetic 

 are more widespread than at present we actually know them to be. 



The functions of the sympathetic and of the other autonomic nerves 

 are tabulated nearly thus by Langley : 



Midbrain's 



autonomous 



nerves. 



SYMPATHETIC. 



Contraction of the iris dilators. 



Contraction of the smooth orbi- 

 tal muscles. 



Contraction of the ocular ar- 

 teries. 



OTHER AUTONOMOUS NERVES. 



Contraction of the iris. 

 Contraction of the ciliary muscles. 



Bulbar autono- 

 mous nerves. 



Sacral autono- 

 mous nerves. 



Acceleration of the heart and 

 contraction of the bloodves- 

 sels of the mucous membranes 

 of the head. 



Inhibitory and motor action on 

 the smooth musculature of 

 the gut from the oesophagus 

 to the descending colon. 



? Secretion in the stomach, liver 

 and pancreas. 



Contraction of the bloodvessels 

 from the oesophagus to the 

 descending colon. 



? Contraction of the bloodvessels 

 of the lung. 



Contraction of the bloodvessels 

 of the intestines. 



Contraction of the smooth mus- 

 culature of the spleen, ureters, 

 and internal sexual organs. 



Contraction of the smooth mus- 

 cles and arteries, and secretion 

 in the skin. 



Inhibition of the heart and (dilata- 

 tion) of the bloodvessels in the 

 mucous membranes of the head. 



Motor and inhibitory action on the 

 smooth musculature of the gut 

 from the oesophagus to the de- 

 scending colon. 



(?) Secretion in the stomach, liver, 

 and pancreas. 



Contraction of the arteries of 

 the rectum, anus, and exter- 

 nal sexual organs. 



Inhibition and contraction of 

 the smooth muscle of the de- 

 scending colon, rectum, and 

 anus. 



Inhibition and contraction of 

 the bladder. 



Contraction (and ? inhibition) of 

 the urethra. 



Contraction of the muscles of 

 the external sexual organs. 



Inhibition of the arteries of the 

 rectum, anus, and external sex- 

 ual organs. 



Contraction of the smooth muscu- 

 lature of the descending colon, 

 rectum, and anus. 



Contraction of the smooth muscle 

 of the anus. 



Contraction of the urinary bladder. 



Inhibition (and ? contraction) of 

 the urethra. 



Inhibition of the muscles of the 

 extern*! sexual organs. 



