THE FACIAL XERVE. 



549 



and separates in the gland, beliind the ramus of the lower maxilla, 

 into two primary divisions, the temporo-facial and the cervico-facial, 

 from wliich numerous branches spread out over the side of the head, 

 the face, and the upper part of the neck, forming what is known as the 

 *' pes anserinus." 



Distribution. — Within the temporal bone the facial is connected 

 with several other nerves by separate branches ; and immediately after 

 issuing from the stylo-mastoid foramen, it gives off" three small branches, 

 viz., tiie posterior auricular, digastric, and stylo-hyoid. 





Fig. 342.— The Facial Nerve 



EXPOSED IN ITS CaNAL, WITH 



ITS Connecting Branches, &c. 

 (froiu Sappey after Hirschfelcl 

 and Leveille). g 



The mastoid and a part of the 

 petrous bone have been divided 

 nearly vertically, and the canal 

 of the facial nerve opened in its 

 whole extent from the meatus 

 internus to the stylo-mastoid 

 foramen. The Vidian canal has 

 also been opened from the out- 

 t-ide. 1, facial nerve in the 

 .horizontal part of the commence- 

 ment of the canal ; 2, its frccond 

 part turning backwards ; 3, its 

 vertical j^ortion ; 4, the nerve at 

 its exit from the stylo-mastoid 

 foramen ; 5, geniculate ganglion ; 



6, laige superficial petrosal nerve passing from this ganglion to the spheno-palatine 

 ganglion, and joined by the small internal i^etrosal bi-anch ; 7, spheno-palatine ganglion ; 

 8, small superficial petrosal nerve; 9, chorda tympani ; 10, posterior auricular branch 

 <iit short at its origin; 11, branch for the digastric muscle; 12, branch for the stjdo- 

 hyoid muscle ; 13, twig to the stylo-glossus muscle uniting with muscular branches 

 of the glosso-pharyngeal nerve (,14 and 15). 



Connecting- Bra:xich.es.—Filament.f of nn'ioa ivith the aud'dory ncvre. — In the 

 meatus auditorius one or two minute filaments pass between the facial and the 

 trunk of the auditory nerve. 



Xi rrcs conmctcd with the [fangllforni oilarr/eiiicnt. — About two lines from the 

 beginning of the aqueduct of Fallopius, where the facial nerve swells into the 

 gangliform enlargement, it is joined by the large superficial petrosal branch, 

 from the Vidian nerve. This ganglion likewise receives a small branch from 

 the small superficial petrosal nerve which unites the otic ganglion with the 

 tympanic nerve of Jacobson, The nerve beyond the ganglion receives the 

 external superficial petrosal nerve (Bidder), which is furnished by the s^-mpa- 

 thetic accompanying the middle meningeal artery, and enters the temporal bone 

 by a canal external to that traversed by the small superficial i^etrosal. 



Chorda Tympani and Nerve to the Stapedius. — The nerve named chorda 

 tympani leaves the trunk of the facial while within its canal, and crosses the 

 tympanum to join the lingual branch of the fifth, along which it is conducted 

 towards the tongue. It enters the back part of the tympanic cavity through a 

 short canal emerging below the level of the pyramid, close to the ring of bone 

 giving attachment to the membrame of the tympanum ; and being invested by 

 the mucous lining of the cavity, it is directed forwards across the membrana 

 tympani and the handle of the malleus, to an apertm-e at the inner end of the 

 Glaserian fissure. It then passes downwards and forwards, under cover of the 

 external pterygoid muscle, and uniting with the lingual nerve at an acute angle, 



