VII 



THE MEDULLA OBLONGATA 



407 



nerve (Fig. 209). Its fibres first pass medialwards and dorsal- 

 wards to form a loop round the nucleus of the abducens, and then 

 turn ventral- and lateralwards to emerge at the upper end of the 

 bulb (Fig. 214). The facial nerve enters the internal auditory 

 meatus along with the 8th nerve, but separates from it at the 

 bottom of the meatus to enter the aqueduct of Fallopius, which 

 it leaves on the lower surface of the skull by the stylo-mastoid 

 foramen (Fig. 215). The facial is accompanied by the nervus 

 intermedius of Wrisberg. 



During its course through the Fallopian canal the facial gives 



FIG. 214. (Left.) Plan of origins of fith and motor root of 7th cerebral nerves. (Thane, adapted 

 from Schwalbe.) The outline represents a transverse section of the lower part of the pons, on 

 to which the course of the facial nerve is projected; vi, 6th nerve; N.VI, its nucleus; vn, 

 facial nerve ; VILA, ascending portion of its root, supposed to be seen in optical section ; 

 N.VII, its nucleus : so, superior olive; AV, sensory or bulbo-spinal root of 5th nerve; VIII.M, 

 mesial root of acoustic nerve. 



FIG. 215. (Right.) Facial nerve in its canal, with its connecting branches, etc. (Sappey, after 

 Hirschfeld and Leveille.) f. The mastoid and a part of the petrous bone have been divided nearly 

 vertically, and the canal of the facial nerve opened in its whole extent from internal meatus to 

 stylo-mastoid foramen ; the Vidian canal has also been opened from the outer side ; 1, facial 

 nerve in first, horizontal part of its course ; 2, its second part, turning backwards ; 3, its 

 vertical portion ; the nerve at its exit from stylo-mastoid foramen ; 5, geniculate ganglion ; 

 6, large superficial petrosal nerve ; 7, spheno-palatine ganglion ; 8, small superficial petrosal 

 nerve; 9, chorda tympani ; 10, posterior, auricular branch cut short; 11, branch to digastric 

 muscle ; 12, branch to stylo-hyoid muscle ; 13, twig uniting with glosso-pharyngeal nerve 

 (14 and 15). 



off two branches to the tympanum, the smaller of which innervates 

 the stapedius muscle, the other which is the chorda tympani 

 passes through the tympanic cavity and unites with the lingual 

 branch of the trigeminal to run partly to the sub-maxillary 

 ganglion, partly to the front part of the tongue. Branches run 

 from the geniculate ganglion through the large superficial petrosal 

 nerve to the spheno-palatine ganglion, from which the palatine 

 branches emerge to supply the muscles of the soft palate, parti- 

 cularly the azygos uvulae and the levator palatini. On leaving 

 the skull the facial sends branches to the external muscles of the 

 ear, the stylo-hyoid and the posterior belly of ' the digastric. At 



