393 ANATOMY OF THE CENTHAL NERVOUS SYSTEM. 



arranged in groups. From these arise continually fibers, extending dorsally. 

 They are gradually gathered to form a good-sized bundle, which, arrived 

 within the floor of the ventricle, suddenly turns forward, and then as sharply 

 bends around to the external side of the bulb. The root of the facialis 

 accordingly makes a double knee {vide Figs. 245, 248, 249, and 250). In this 

 knee is deposited the nucleus of the abducens nerve. 



To the trunk of the root of the facial nerve pass fibers from the ascending root 

 of the trigeminal. This is, perhaps, important, because we know that from this por- 

 tion of the trigeminus are derived the sensory fibers for the face. 



At precisely the place where the facialis makes its exit from the brai?! 

 there enters in a thin, delicate nerve-trunk, that has accompanied the pe- 

 ripheral course of the facial. It is the portio intermedia Wrisbergi. 



Duval first discovered that it arises from the superior end of the glosso-pharyn- 

 geal nucleus (KoUiker says from the nucleus of the fasciculus solitarius), and P. 



Fig. 249. — Schema of the central path of the nervus facialis and nervus abducens. 



Martin and His corroborate this. The latter were able to demonstrate in the em- 

 bryo that fibers grow into the brain from the ganglion geniculi nervi facialis. 



The ganglion geniculi — besides being principally a sympathetic gan- 

 glion (Lenhossek) — is then the nucleus of origin of the portio intermedia, 

 while the anterior' portion of the fasciculus solitarius is its central nucleus. 



The roots of the abducens arrive by several extended bundles, which pass 

 through the tegmentum and the pons, at the base of the pons externally. 

 On the median side the nucleus is connected with the posterior longitudinal 

 bundle. It is claimed, though not well proved, that these fibers higher up 

 enter the opposite motor-octili nerve. Without doubt, however, there is a 

 remarkable connection between the abducens nucleus and the superior olive. 

 This connecting tract, which is shown in Fig ,24S parallel to the root of the 

 facial, must place the acusticus in connection with the motor nerves to the 

 eyes, and is, perhaps, of importance for the maintenance of position in space. 



