FACIAL NERVE. 



611 



pan urn it is turned suddenly backwards above the fenestra ovalis towards the 

 pyramid. At the place where it bends, the nerve presents a reddish gangli- 

 furm enlargement, sometimes called the geniculate ganglion, which marks the 

 place of junction of several nerves. Opposite the pyramid it is arched down- 

 wards behind the tympanum to the stylo-inastoid foramen, by which it leaves 

 the osseous canal. It is then continued forwards through the substance of 

 the parotid gland, and separates iii the gland, behind the ramus of the lower 

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

 facial, from which 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." 



\Vithin 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., the posterior 

 auricular, digastric, and stylo-hyoid. 



Fig. 411. THE FACIAL NKRVB Fig. 411. 



EXPOSED IN ITS CANAL, WITH ITS 



CONNECTING BRANCHES, &c. 

 (from Sappey after Hirschfeld 

 and Leveille). 



The mastoid and a part of the 

 petrous bone have been divided 

 nearly vertically, arid the canal of 

 the facial nerve opened iu its whole 

 extent from the meatus internus 

 to the stylo-mastoid foramen. The 

 Vidian canal has also been opened 

 from the outside. 1, facial nerve 

 in the horizontal part of the com- 

 mencement of the canal ; 2, its 

 second part turning backwards ; 

 3, its vertical portion ; 4, the 

 nerve at its exit from the stylo- 

 mastoid foramen ; 5, geniculate 

 ganglion ; 6, large superficial pe- 



trosal nerve passing from this ganglion to the spheno-palatine ganglion, and joined by 

 the small internal petrosal branch; 7, spheno-palatine ganglion; 8, small superficial 

 petrosal nerve ; 9, chorda tympani ; 10, posterior auricular branch cut short at its origin ; 

 11, branch for the digastric muscle ; 12, branch for the stylo-hyoid muscle ; 13, twig to 

 the stylo-glossus muscle uniting with muscular branches of the glosso-pharyngeal nerve 

 (14 and 15). 



CONNECTING BRANCHES. 



Filaments of union with the auditory nerve. In the meatus auditorius one or two 

 minute filaments pass between the facial and the trunk of the auditory nerve. 



Nerves connected with the gangliform enlargement. About two lines from the 

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

 form 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 sympathetic accompanying tlie middle meningeal 

 artery, and enters the temporal bone by a canal external to that traversed by the 

 small superficial petrosal. 



CHOKDA 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 gustatory nerve, along which it i> con- 



