GLOSSOPHARYNGEAL NERVE. 



785 



i.e. 



from the nervus intermedius, and gives off a communicating branch to the 

 genicular ganglion of the facial nerve. It then separates into three terminal 

 branches which pierce the lamina cribrosa. (1) N. Utricularis. The utricular 

 nerve supplies the macula acustica of the utricle. (2) and (3) Nn. Ampullaris Superior 

 et Lateralis. The superior and lateral ampullary nerves supply the ampullae of the 

 superior and lateral semicircular ducts. 



The inferior division gives off (1) n. saccularis, a saccular nerve to the macula 

 acustica of the saccule, (2) n. ampullaris inferior, an inferior ampullary nerve to the 

 ampulla of the posterior semicircular duct, and (3) is continued through the lamina 

 cribrosa to the labyrinth as the cochlear nerve, which is distributed through the 

 modiolus and osseous spiral lamina to the organ of Corti in the cochlea. 



Both the vestibular and cochlear nerves contain among their fibres collections of nerve 

 cells, forming in each nerve a distinct ganglion the vestibular ganglion on the vestibular 

 trunk, and the ganglion spirale or spiral ganglion of the cochlea on the cochlear trunk. 



NERVUS G-LOSSOPHARYNGEUS. 



The ninth or glossopharyngeal nerve (Fig. 643, p. 768) arises from the brain 

 by five or six fine fila radicularia (radicles) which emerge from the medulla oblongata, 

 between the posterior and lateral 

 columns, close to the facial nerve 

 above, and in series with the fila 

 of the vagus nerve below (for the 

 deep connexions, see p. 596). The 

 fila combine to form a nerve which 

 passes through the jugular fora- 

 men, along with the vagus and 

 accessory nerves, but enveloped in 

 a separate sheath of dura mater 

 (Fig. 647, p. 771). Eeaching the 

 neck, the nerve arches downwards 

 and forwards to the interval be- 

 tween the hyoid bone and the 

 mandible. In its course to the side 

 of the pharynx it lies at first- be- 

 tween the internal carotid artery 

 and the internal jugular vein, and 

 then between the internal and ex- 

 ternal carotid arteries. It sweeps 

 round the stylopharyngeus muscle 

 and the stylo-hyoid ligament, and 

 disappears medial to the hyoglossus 

 muscle, to reach its termination in 

 the tongue. 



The branches of the nerve mav , 



.,. - *V FIG. 659. SCHEME OF THE DISTRIBUTION OF THE GLOSSO- 



Dlassined in three series accord- PHARTOGEAL NERVE. 



to their Origin (i.) in the G . Pllj Glossopharyngeal nerve ; J, Superior, and P, Petrous 

 JUgular foramen ; (ii.) in the nei^k ; ganglia ; Ty, Tympanic nerve ; Ty.Plex., Tympanic plexus; 



Fa, Root from genicular ganglion of facial nerve; S.S.P. 



Sy. 



(iii.) in relation to the tongue. 



In the jugular foramen there 

 are two enlargements upon the 

 trunk of the nerve the superior 

 and petrous ganglia. The superior 

 ganglion (O.T. jugular) is small, 

 does not implicate the whole width 

 of the nerve, and may be fused 

 with the petrous ganglion, or 

 even absent altogether. No branches arise from it. 



G-anglion Petrosum. The petrous ganglion is distinct and constant. It is 

 placed upon the nerve at the lower part of its course through the jugular foramen. 



51 



Lesser superficial petrosal nerve to the otic ganglion ; S.D.P, 

 Carotico-tympanic nerve ; I.C, Internal carotid artery ; Va, 

 Vagus nerve ; Aur., Auricular branch of vagus ; Sy., 

 Superior cervical sympathetic ganglion ; F, Communicating 

 branch to facial nerve ; Ph, Pharyngeal branch of vagus ; 

 E.C, External carotid artery ; Ph. PI, Pharyngeal plexus ; 

 S.Ph, Stylopharyngeus muscle; S.H.L, Stylo-hyoid liga- 

 ment; H.G, Hyoglossus; S.G, Styloglossus ; Ton, Palatine 

 tonsil; S. Pal., Soft palate; G.H.G, Genioglossus ; G.H, 

 Genio-hyoid ; Hy, Hyoid bone. 



