660 SYMPATHETIC AND OTHER SYSTEMS OF NERVES. 



inapplicable to some of the structures brought under it, such as the 

 nerve fibres which run to the skin. I propose, then, following a 

 suggestion of Professor Jebb, to use the word " autonomic," including 

 under that term the contractile cells, unstriated muscle, cardiac 

 muscle, and gland cells of the body, together with the nerve cells and 

 fibres in connection with them. 



The autonomic nervous system consists of the sympathetic system, 

 which we have already in large part considered, of the cranial autonomic 

 system, the sacral autonomic system, and the enteric system (the 

 plexuses of Auerbach and Meissner), which we will now pass on to con- 

 sider. The interstitial cells of Cajal, if they are nervous, also belong to 

 the autonomic system. 



DISTRIBUTION AND ACTION OF CRANIAL AUTONOMIC NERVE FIBRES. 



Autonomic nerve fibres leave the brain by way of the third, seventh, 

 ninth, tenth, and eleventh cranial nerves. 



Third nerve. — The third cranial nerve sends a branch to the ciliary 

 ganglion, and in this the efferent fibres end. The connection is shown 

 both by the nicotin x and by the degeneration method. 2 If the third 

 nerve be cut in the skull, numerous degenerated fibres are found 

 running to the ganglion, but no degenerated fibres are found peripherally 

 of it. The post-ganglionic fibres form — with the addition of a few fibres 

 from the fifth nerve — the short ciliary nerves, which give motor fibres 

 to the sphincter pupill^ and to the ciliary muscle. 



Seventh and ninth nerves. — The seventh and the ninth nerves we 

 may to a certain extent consider together, since the autonomic fibres of 

 the seventh are, so far as is known, contained in the intermediate 

 nerve of Wrisberg, and this may be regarded as the continuation 

 anteriorly of the ninth. Moreover, the two together probably supply 

 with autonomic fibres the whole of the mucous membrane of the nose 

 and mouth. 



The seventh and the ninth nerves together supply in the dog 

 secreting fibres to the orbital gland, the glands of the lips and cheek, 

 and the salivary glands. The fibres run in the several branches of the 

 fifth nerve supplying the respective glands, for stimulation of these 

 branches causes secretion, and, after section of any one branch, stimula- 

 tion of the seventh and ninth nerves has no longer an effect in the 

 region to which the cut branch runs. 



The seventh and ninth nerves have also been shown to send vaso- 

 dilator fibres by way of the fifth to the greater part of the region to 

 which they send secretory fibres, namely, to all the salivary glands, to 

 the tongue, to the mucous membrane of the floor of the mouth, and to 

 part of the soft palate. They have not been shown to send vaso-dilator 

 fibres to the mucous membrane of the cheeks and gums. According to 

 Vulpian, indeed, stimulation of the seventh and ninth nerves intra- 

 cranially does not cause flushing of the lips and cheeks, but since it does 

 cause secretion from glands in this region, and since in other cases the 



1 Langley and Anderson, Journ. Physiol., Cambridge and London, 1892, vol. xiii. 

 p. 460. 



2 Jegorow, Arch, slaves tie biol., Paris, 1887, tome iii. p. 322. (Jegorow, notwith- 

 standing his results, was inclined to consider the ciliary ganglion as homologous to a 

 posterior root ganglion.) Langley and Anderson, Journ. Physiol., Cambridge and London, 

 1894, vol. xvii. p. 184. 



