252 



THE CRANIAL NERVES. 



The fibres of this part have been traced centrally to the upper end of the glosso- 

 pharyngeal nucleus (Duval). It is frequently connected more or less closely at its 

 emergence with one or both of the nerves between which it lies, and in many cases 

 a few of its fibres pass distally into the auditory nerve. 



The fibres of the facial nerve are mostly of medium size, but the portio intermedia 

 consists almost wholly of very small fibres. Indications of a degenerated ganglion are found 

 in the facial nerve close to its exit from the bulb (Thomsen, Gaskell). 



From its superficial origin, the facial nerve is directed outwards in company with 

 the auditory nerve to the internal auditory meatus. Here the facial lies in a groove 

 along the upper and fore part of the auditory nerve, and the portio intermedia is 

 placed between the two. At the bottom of the meatus the facial nerve enters the 



Fig. 169. GENICULATE GANGLION OF THE FACIAL NERVE 



AND ITS CONNECTIONS FKCM ABOVE. (Bidder.) 



The dissection is made in the middle fossa of the 

 skull on the right side, part of the temporal bone being 

 removed so as to open the internal auditory meatus, 

 hiatus Fallopii, and a part of the canal of the facial 

 nerve, together with the cavity of the tympanum ; a, 

 auricle ; b, middle fossa of the skull with the meningeal 

 artery ramifying in it ; 1, facial and auditory nerves in 

 the internal auditory meatus ; 2, large superficial 

 petrosal nerve ; 3, small superficial petrosal nerve lying 

 over the tensor tympani muscle ; 4, external superficial 

 petrosal nerve joining sympathetic twig on the meningeal 

 artery ; 5, facial and chorda tympani ; 6, nerves enter- 

 ing the jugular foramen. 



aqueduct of Fallopius, and follows the wind- 

 ings of that canal through the temporal bone 

 to the lower surface of the skull. It passes 

 at first horizontally outwards for a short 

 distance, between the cochlea and vestibule, 



to the inner wall of the tympanum, where it bends sharply backwards above the 

 fenestra ovalis, and then arches downwards behind the pyramid and the tympanic 

 cavity to issue by the stylo-mastoid foramen. At the place where it turns backwards 

 (outer genu ; genicul^m n. facial-is) f the nerve presents on its fore part a reddish 

 enlargement which contains unipolar nerve-cells, and is named the geniculate 

 ganglion (ganglion geniculi). This ganglion is mainly connected with the portio 

 intermedia, and the fibres which proceed from its cells (both proximally and distally) 

 are probably afferent. Below the skull, the facial trunk is continued downwards 

 and tor-wards through the substance of the parotid gland ; and a little behind the 

 ramus of the lower jaw it terminates by dividing into two parts, temper o-facial and 

 cervico-facial, from which numerous branches spread over the side of the head, the 

 face, and the upper part of the neck, communicating freely with one another, and 

 thus forming a radiating plexus to which the name of pes anserinus or p!r.riis 

 parotideus has been given. 



BRANCHES. A. Arising from the facial nerve during its course through the 

 temporal bone. 



Communicating filaments with the auditory nerve. These are one or 

 two slender twigs passing between the geniculate ganglion and the upper division of 

 the eighth nerve at the bottom of the internal auditory meatus, and probably con- 

 veying to the facial nerve fibres derived from the portio intermedia. 



The large superficial petrosal nerve is directed forwards from the geniculate 

 ganglion, and issues by the hiatus Fallopii on the upper surface of the petrous 



