668 ORIGIN OF NERVES. 



times adlierent. Its fibres pass backwards and a little outwards, to 

 reach the nucleus conunon to this and the facial nerve, a column of 

 large multipolar nerve-cells, beneath the eminentia teres in the middle 

 of the floor of the fourth ventricle. In the inner part of this nucleus 

 most of the fibres end. 



The facial nerve {portio dura of the seventh pair) appears at the 

 lower border of the pons Varolii in a line with the attachment of the 

 fifth nerves. It emerges from the medulla oblongata, in the outer part 

 of the depression between the olivary body and the diverging restiforni 

 body (inferior peduncle of cerebellum), and. is often firmly adherent, as 

 a flattened band, to the lower edge and even for a short distance to the 

 upper surface of the pons. On its outer side is the auditory nerve. 

 A separate fasciculus of the facial nerve (intermediate part) is sometimes 

 attached to both auditory and facial nerves. 



The fibres pass backwards and inwards through the medulla towards 

 the floor of the fourth ventricle, where many end in the outer part of 

 the common nucleus, just described as lying beneath the eminentia teres 

 in the middle of the fourth ventricle. A considerable number of fibres 

 pass above the nucleus and turn round it, just beneath the surface of 

 the ventricular floor, to descend as a compact bundle on the inner side 

 of the common nucleus ; lower down these fibres diverge outwards and 

 forwards to the superior olivary body and adjacent lower part of the 

 nucleus of the motor root of the fifth nerve (fig. 359). 



The auditory nerve {portio mollis of the sevcntJi pair) appears at 

 the lower edge of the pons on the outer side of and close to the facial 

 nerve. It is also united to the lower edge of the pons opposite the 

 inner side or middle of the restiform body from which it emerges. A 

 large and conspicuous portion of the nerve curves outv.'ards round the 

 restiform body. 



The fibres of the nerve divide into two corresponding bundles, one the 

 posterior, winds round the restiform body, with which it is connected by 

 some fibres of origin, to reach the inner auditory nucleus, a large col- 

 lection of nerve cells, in the outer side of the lower part of the floor of 

 the fourth ventricle. The other, or anterior division, passes, a little 

 higher up, through the substance of the restiform body to end chiefly in 

 the outer auditory nucleus, a network of cells and fibres, to the outer 

 side of the inner nucleus and of this part of the nerve. Some of its 

 fibres go to the inner nucleus, others pass with the restiform body to the 

 cerebellum. Both portions contain much grey matter, which on the 

 posterior part forms a pyriform swelling. The trunk is also joined by 

 some fibres from the strife mcdullares. 



The glosso-pharyngeal nerve arises from the side of tlie medulla 

 by a series of five or six roots attached in a vertitsal line to the surface 

 of the restiform body, the highest being close to the auditory nerve. 

 The fibres pass backwards and inwards, through the medulla, to reach a 

 column of nerve-cells placed deeply beneath the lower and outer part of 

 the floor of the fourth ventricle, between the highest part of the vagal 

 nucleus and the lower part of the internal auditory nucleus. 



The pneuiuogastric or vagus nerve arises from the side of the 

 medulla by a series of twelve or more roots, which are attached to the 

 restiform body in a vertical line below those of the glosso-pharyngeal 

 nerve. The fibres pass backwards to a large group of nerve cells be- 

 neath the lowest part of the floor of the fourth ventricle, where they 



