AUDITORY NERVE. 447 



that cavity through an opening situated between the base of the pyra- 

 mid and the attachment of the membrana tympani, and becomes in- 

 vested by mucous membrane. It then crosses the tympanum between 

 the handle of the malleus and long process of the incus to the anterior 

 inferior angle of the cavity, and escapes through a distinct opening in 

 the fissura Glaseri, and joins the gustatory nerve at an acute angle be- 

 tween the two pterygoid muscles. Enclosed in the sheath of the gus- 

 tatory nerve, it descends to the submaxillary gland, where it unites 

 with the submaxillary ganglion. 



The Posterior auricular nerve ascends behind the ear, between the 

 meatus and mastoid process, and divides into an anterior and a poste- 

 rior branch. The anterior branch receives a filament of communication 

 from the auricular branch of the pneumogastric nerve, and distributes 

 filaments to the retrahens and attollens aurem muscles and to the pinna. 

 The posterior branch communicates with the auricularis magnus and 

 occipitalis minor, and is distributed to the posterior belly of the occi- 

 pito-frontalis. 



The Stylo-hyoid branch is distributed to the stylo-hyoid muscle. 



The Digastric branch supplies the posterior belly of the digastricus 

 muscle, and communicates with the glosso-pharyngeal and pneumogas- 

 tric nerve. 



The Temporo-facial gives off a number of branches which are dis- 

 tributed over the temple and upper half of the face, supplying the 

 muscles of this region, and communicating with the branches of the 

 auricular, the subcutaneus malae, and the supra-orbital nerve. The 

 inferior branches, which accompany Stenon's duct, and form a plexus 

 with the terminal branches of the infra-orbital nerve. 



The Cervico-facial divides into a number of branches that are dis- 

 tributed to muscles on the lower half of the face and upper part of 

 the neck. The cervical branches form a plexus with the superficialis 

 colli nerve over the submaxillary gland, and are distributed to the pla- 

 tysma myoides. 



AUDITORY NERVE (portio mollis). The auditory nerve takes its 

 origin in the lineae transversse (striae medullares) of the anterior wall 

 or floor of the fourth ventricle, and winds around the corpus restiforme, 

 from which it receives fibres, to the posterior border of the cms cere- 

 belli. It then passes forwards upon the eras cerebelli in company 

 with the facial nerve, which lies in a groove on its superior surface, 

 and enters the meatus auditorius internus, and at the bottom of the 

 meatus it divides into two branches, cochlear and vestibular. The au- 

 ditory nerve is soft and pulpy in texture, and receives in the meatus 

 auditorius several filaments from the facial nerve. 



EIGHTH PAIR. The eighth pair consists of three nerves, glosso- 

 pharyngeal, pneumogastric, and spinal accessory ; these are the ninth, 

 tenth, and eleventh pairs of Soemmering. 



GLOSSO-FHARYXGEAL NERVE. The glosso-pharyngeal nerve arises 



