258 



THE CRANIAL NERVES. 



in the bony wall of the cochlea, and is called the spiral ganglion. The cells in these 

 ganglia are bipolar. (See the anatomy of the ear.) 



The auditory nerve often receives some of the fibres of the portio intermedia, 

 and its upper division is connected at the bottom of the internal auditory meatus 

 with the geniculate ganglion of the facial nerve (see p. 252). 



The branches of the auditory nerve, together with the apertures by which they leave the 

 nieatus, are shown in the following table : 



Utricular nerve . . . ^ 

 Superior ampullary nerve 

 External ampullary nerve 

 Saccular nerve . 

 Posterior ampuliary nerve 



Superior division or vesti- 

 bular nerve 



Inferior division 



Posterior 

 branch 



> Area cribrosa superior. 



Cochlear nerve 



. Area cribrosa media. 

 . Foramen singulare. 



( Tractus spiralis foraminu- 

 . < lentus and foramen cen- 



( trale cochleae. 



IX. GLOSSO-PHARYNGEAL NERVE. 



The ninth or glosso-pharyngeal nerve emerges from the upper part of the 

 medulla oblongata, in the groove between the olivary and restiform bodies, by five 



Fig. 174. PLAN OF THE ORIGIN OF THE GLOSSO-PHARYNGEAL 

 NERVE. (After Obersteiner. ) 



The outline represents a transverse section of the upper 

 end of the bulb : IX, roots of the glosso-pharyngeal nerve ; 

 F.S. , funiculus solitarius ; N.IX, glosso-pharyngeal nucleus ; 

 N.AM., nucleus ambiguus ; A.V, ascending or bulbar root of 

 the fifth nerve. 



or six filaments arranged in a vertical line com- 

 mencing immediately below the facial nerve. 



From this spot the rootlets of the nerve pass 

 backwards and inwards through the bulb to the 

 special nucleus beneath the inferior fovea in the 

 floor of the fourth ventricle ; some of the fibres 

 turn downwards into the funiculus solitarius, and 



others, probably efferent, bend forwards to the upper prolongation of the accessory 



vagal nucleus (nucleus ambiguus). 



The glosso-pharyngeal is composed almost entirely of very fine fibres, but mixed with 

 these there are a few of medium size. 



From its superficial origin, the glosso-pharyngeal nerve is directed outwards in 

 front of the flocculus to the middle compartment of the jugular foramen, through 

 which it passes in company with the pneumo-gastric and spinal accessory nerves, 

 but in a separate tube of dura mater. In the foramen, where it is placed external 

 to and somewhat in front of the other nerves, it is lodged in a groove, occasionally 

 a canal, in the lower border of the petrous portion of the temporal bone, and it pre- 

 sents, successively, two ganglionic enlargements the jugular ganglion and the 

 petrosal ganglion, containing unipolar nerve-cells, like those of the spinal ganglia. 



After leaving the skull, the glosso-pharyngeal nerve appears between the internal 

 carotid artery and the jugular vein, and is directed downwards over the carotid 

 artery and beneath the styloid process and the muscles connected with it, to the 

 hinder border of the stylo-pharyngeus ; then curving gradually forwards, it crosses 



