THE CEREBRAL NERVES 



363 



The peripheral processes of the ganglion cells form the greater part of the vagus 

 trunks after the separation from it of the spinal accessory fibers. 



Vagus root gang. 



Accessory root gang. 



IX root qa 



Gang, petro 

 N. tymp. 



Br to 

 carotid pi' 



Gang. 

 Froriep. 



Sympathetic 

 Fig. 346. — A reconstruction of the peripheral nerves in an embryo of 17.5 mm. (Streeter). X 16.7. 



In aquatic vertebrates special somatic sensory fibers from the lateral line organs join the 

 facial, glossopharyngeal and vagus nerves, and their ganglion cells form part of the geniculate, 

 petrosal and nodose ganglia. In human embryos the organs of the lateral line are represented 

 by ectodermal thickenings or placodes which occur temporarily over the geniculate, petrosal 



