1000 



THE NERVE SYSTEM 



joins the small superficial petrosal nerve; and also with the sympathetic filaments 

 accompanying the middle meningeal artery, by the external petrosal nerve (Bidder). 

 From the gangliform enlargement, according to Arnold, a twig is sent back to 

 the auditory nerve. Just before the facial nerve emerges from the stylomastoid 

 foramen it generally receives a twig of communication from the auricular branch 

 of the vagus. 



After its exit from the stylomastoid foramen, it sends a twig to the glosso- 

 pharyngeal, another to the vagus nerve, and communicates with the great auricular 

 branch of the cervical plexus, with the auriculotemporal branch of the inferior 

 maxillary nerve in the parotid gland, with the small occipital nerve behind the 

 ear, on the face with the terminal branches of the three divisions of the fifth, 

 and in the neck with the transverse cervical. 



Branches of Distribution (Fig. 740). The branches of distribution of the facial 

 nerves may be thus arranged: 



Within the canalis facialis or aquae- f Tympanic, to the Stapedius muscle, 

 ductus Fallopii ) Chorda tympani. 



. ., ' ., e ,1 ,1 . i ( Posterior Auricular. 

 At its exit from the stylomastoid TA . 



. \ Digastric. 



roramen c ,, s , . , 



^ btylohyoid. 



C Temporal. 

 C Temporofacial . . < Malar. 



On the face L Infraorbital. 



| BuccaL 



[_ Cervicofacial . . < Mandibular. 



[^ Cervical. 



The Tympanic Branch (n. Stapedius) (Fig. 740) arises from the nerve opposite 

 the pyramid; it passes through a small canal in the pyramid and supplies the 

 Stapedius muscle. 



The Chorda Tympani (Figs. 739 and 740) is apparently given off from the facial 

 as it passes vertically downward at the back of the tympanum, about 5 mm. 

 ( inch) before its exit from the stylomastoid foramen. It passes from below 

 upward and forward in a distinct canal, and enters the cavity of the tympanum 

 through an aperture (iter chordae postering) on its posterior wall between the open- 

 ing of the mastoid cells and the attachment of the membrana tympani, and be- 

 comes invested with mucous membrane. It traverses the cavity of the tympanum, 

 between the fibrous and mucous layers of the membrana tympani, crosses over the 

 handle of the malleus, emerges from the cavity through a foramen at the inner 

 end of the Glaserian fissure, which is called the canal of Huguier (iter chordae 

 anterius). It then descends between the two Pterygoid muscles on the inner 

 aspect of the spine of the sphenoid, which it sometimes grooves, and joins the 

 lingual nerve at an acute angle. A portion of the nerve (excitoglandular division) 

 passes to the submaxillary ganglion; the rest is continued onward through the 

 muscular substance of the tongue to the mucous membrane covering its anterior 

 two-thirds. These constitute the nerves of taste for this portion of the tongue. 

 A few of its fibres probably pass through the suBmaxillary ganglion to the sub- 

 lingual gland. Before joining the lingual nerve it receives a small communicating 

 branch from the otic ganglion. As already stated, the chorda tympani -nerve 

 is regarded as the peripheral portion of the nervus intermedius (see p. 998). 



The Posterior Auricular Nerve (n. auriculus posterior} (Figs. 740 and 741) arises 

 close to the stylomastoid foramen, and passes upward in front of the mastoid 

 process and between the mastoid process and the external ear, where it is joined 

 by a filament from the auricular branch of the vagus, and communicates with the 



