THE CRANIAL NERVES 287 



the portio dura and the portio mollis. Running between 

 them is a fasciculus from the medulla known as the inter- 

 mediary nerve of Wrisberg, or the portio inter duram et 

 mollem; most of its fibers join the facial in the internal audi- 

 tory meatus. The facial nerve enters the Fallopian aque- 

 duct at the bottom of the meatus and follows it to issue at 

 the stylo-mastoid foramen, runs forward in the substance of 

 the parotid gland and divides behind the ramus of the jaw 

 into temp or -o- -facial and cervico -facial branches. 



Its branches of communication are numerous. ( i ) In the 

 internal auditory meatus it communicates with the auditory 

 nerve; (2) in the aqueductus Fallopii with the otic and 

 spheno-palatine ganglia, with the sympathetic and with the 

 auricular branch of the pneumogastric ; (3) after leaving 

 the stylo-mastoid foramen, with the fifth, ninth, tenth and 

 sympathetic. 



Its branches of distribution are also quite numerous, (i) 

 In the aqueductus Fallopii it gives off (a) the tympanic 

 branch to the stapedius muscle, and (b] the chorda tympani, 

 which passes through the cavity of the tympanum and 

 emerges by a foramen at the inner end of the Glasserian 

 fissure to go to the lingual branch of the fifth. (2) At its 

 exit from the stylo-mastoid foramen it gives off (a) a 

 posterior auricular branch which, receiving a filament from 

 the auricular branch of the tenth, is distributed to the retra- 

 hens aurem and the occipital portion of the occipito-fron- 

 talis; (6) a digastric branch to the posterior Ipelly of the di- 

 gastric muscle; (c) a stylo-hyoid branch to the muscle of 

 that name. (3) On the face it divides into (a) a temporo- 

 facial branch, which is distributed to the muscles over the 

 temple and upper face; and (b) a cervico-facial branch, 

 which is distributed to the lower face and upper cervical 

 region. 



Functions. This is the motor nerve of the muscles of ex- 

 pression, of the platysma, buccinator, digastric (posterior 

 belly), stylo-hyoid, the muscles of the external ear and the 



