998 



THE NERVE SYSTEM 



nerve some fibres arise which descend in the medial longitudinal bundle and join 

 the facial just before it leaves the pars dorsalis pontis; these fibres are said to supply 

 the anterior belly of the Oc^pitofrontalis, the Orbicularis palpebrarum, and the 

 Corrugator supercilii, as these muscles have been observed to escape paralysis 

 in lesions of the nucleus of the facial nerve. 



The acoustic or auditory nerve lies to the outer side of the facial nerve; and between the 

 two is a small fasciculus, the nervus intermedius or pars intermedia of Wrisberg, which 

 apparently arises from the medulla oblongata and joins the facial nerve in the internal auditory 

 meatus. The central processes of the ganglion cells, known as the nervus intermedius, end 

 in the upper end of the nucleus of the glossopharyngeal nerve. If it is to be classified as part 

 of the facial then the nervus intermedius may be regarded as the sensor root of the facial 

 nerve, analogous to the sensor root of the trigeminal, and its real nucleus of origin consists of 

 the geniculate ganglion (see p. 884). It will be remembered that a portion of the nervus inter- 

 medius is efferent (excitoglandular), arising from the nucleus salivatorius (p. 884). 



Nucleus Salivatorius 



Superior Maxillary N, 

 Vidian N. 



Temporal 

 /Malar 



Infraorbital 

 Buccal 

 -Supramaxillary 



Imframaxillary 



Post 

 Auricular Br. 



To Digastric 

 To Stylo-hyoid 



Afferent (taste) fibers 



Efferent < excitoglandular) 



fibers to submaxillary and 



sublingual ganglia and glands 



FIG. 740. Plan of the facial and intermediate nerves and their communication with other nerves. 



The facial nerve, firmer, rounder, and smaller than the auditory, passes forward 

 and outward upon the middle peduncle of the cerebellum, and enters the internal 

 auditory meatus with the auditory nerve and artery. Within the meatus the facial 

 nerve lies in a groove along the upper and anterior part of the auditory nerve, 

 and the nervus intermedius is placed between the two and joins the inner angle 

 of the geniculate ganglion. Beyond the ganglion its fibres are generally regarded 

 as forming the chorda tympani (see p. 1000). 



At the bottom of the meatus the facial nerve enters the canalis facialis or aquae- 

 ductus Fallopii and follows the course of that canal through the petrous portion of 

 the temporal bone, from its commencement at the internal meatus to its termina- 

 tion at the stylomastoid foramen (Figs. 50 and 739). It is at first directed outward 

 between the cochlea and vestibule toward the inner wall of the tympanum; it. 



