MOTOR FUNCTIONS OF THE BULBO-SACRAL O UTFLO W 61 



to the muscle and so causes its contraction. It is possible 

 that the nerve cell near the muscle, with which the second col- 

 lateral makes connexion, may also be a motor nerve cell to this 

 musculature, but the phenomenon of the axon reflex does not 

 of necessity imply this, for it would occur equally well if this 

 nerve cell was an inhibitory cell to this musculature or indeed if 

 it supplied motor or inhibitory nerves to some other musculature. 



The segmental cranial nerves, which form the mesosomatic 

 groups, are the 7th, pth, and loth nerves, and all these 

 nerves supply connector fibres to peripheral ganglia, similarly to 

 the segmental nerves already considered. Apart from ganglion 

 cells on the oesophagus, to which the glossopharyngeal apparently 

 sends connector fibres as well as the vagus, we have still for con- 

 sideration such ganglia as the submaxillary, the otic and the 

 spheno-palatine (Fig. 6). 



The secretory fibres to the parotid gland, equivalent to the 

 motor fibres of involuntary muscle, arise from nerve cells in the 

 otic ganglion, and the connector fibres to these cells pass out in 

 the glossopharyngeal nerve and travel by way of the nervus tym- 

 panicus and lesser superficial petrosal nerves to the otic ganglion. 



The secretory fibres to the submaxillary and sublingual 

 glands arise from the submaxillary and sublingual ganglia, and 

 their connector fibres pass out in the facial nerve and travel by 

 way of the chorda tympani to these ganglia. 



The spheno-palatine ganglion supplies motor and secretory 

 fibres in the palatine nerves to unstriped muscle and glands in 

 the region of the palate, and the connector fibres, with which 

 it is connected, run in the facial outflow by way of the great 

 superficial petrosal nerve. They also supply secretory fibres to 

 the lacrymal glands. 



An outflow of connector fibres to neurons of the involuntary 

 system has therefore occurred in all the mesosomatic segmental 

 nerves. 



In summing up the results of this chapter, we see that the 

 motor nerve cells, which are connected with the central nervous 

 system by bulbar and sacral connector nerves, supply with motor 

 fibres a well-defined system of unstriped muscles, which are 

 situated just under the lining surface of the alimentary canal and 

 its diverticula ; a system to which the name endodermal may 

 be legitimately applied. The motor cells of this endodermal 



