THE SEVENTH OR FACIAL NERVE. 



813 



ward at the back of the tympanum, about a quarter of an inch before its exit 

 from the stvlo-mastoid foramen. It passes from below upward and forward in a 



Ganglion of_ 

 Lateral Root 



Mesial Root 



(Accessory) Ventral Auditory 

 Nitcleus 



FIG. 488. Mode of origin of auditory nerve (diagrammatic). [The section is dorso-ventrally, between pons 

 and medulla.] 



distinct canal, and enters the cavity of the tympanum through an aperture (iter 

 chordae posterius) on its posterior Avail between the opening of the mastoid cells 

 and the attachment of the membrana tympani, and becomes invested with mucous 

 membrane. It passes forward through the cavity of the tympanum, between the 

 handle of the malleus and vertical ramus of the incus, to its anterior inferior 

 angle, and emerges from that cavity through a foramen at the inner end of the 

 Glaserian fissure, which is called the iter chordce anterius, or canal of Huguier. 

 It then descends between the two Pterygoid muscles, meets the lingual nerve 

 at an acute angle, and accompanies it to the submaxillary gland ; part of it then 

 joins the submaxillary ganglion ; the rest is continued onward into the proper 

 muscular fibres of the tongue the Inferior lingualis muscle. A few of its fibres 

 probably pass through the submaxillary ganglion to the sublingual gland. Before 

 joining the lingual nerve it receives a small communicating branch from the 

 otic ganglion. 



The Posterior auricular nerve arises close to the stylo-mastoid foramen, and 

 passes upAvard in front of the mastoid process, where it is joined by a filament 

 from the auricular branch of the pneumogastric, and communicates with the 

 mastoid branch of the auricularis magnus and with the small occipital. As it 

 ascends between the meatus and mastoid process it divides into two branches. 

 The auricular branch supplies the Retrahens aurem and the small muscles on the 

 cranial surface of the pinna. The occipital branch, the larger, passes backward 

 along the superior curved line of the occipital bone, and supplies the occipital 

 portion of the Occipito-frontalis. 



The digastric branch usually arises by a common trunk with the Stylo-h-yoid 

 branch : it divides into several filaments, which supply the posterior belly of the 

 Digastric; one of these perforates that muscle to join the glosso-pharyngeal nerve. 



The stylo-hyoid is a long slender branch, which passes inward, entering the 

 Stylo-hyoid muscle about its middle; it communicates with the sympathetic 

 filaments on the external carotid artery. 



The Temporo-facial, the larger of the two terminal branches, passes upward 

 and forward through the parotid glands, crosses the external carotid artery and 



