552 NERVOUS SYSTEM. 



The main root of the facial, the auditory nerve and the intermediary 

 nerve of Wrisberg pass together into the internal auditoYy meatus. At the 

 bottom of the mejitus, the facial and the nerve of Wrisberg enter the aquge- 

 ductus Fallopii, following its course through the petrous portion of the tem- 

 poral bone. In the aqueduct the nerve of Wrisberg presents a little, ganglio- 

 form enlargement (geniculate ganglion) of a reddish color, which has been 

 shown to contain nerve-cells. The main root and the intermediary nerve 

 then unite and form the common trunk of the facial, which emerges from 

 the cranial cavity, by the stylo-mastoid foramen. 



In the aquseductus Fallopii the facial gives off the following branches : 



1. The large petrosal branch is given off at the ganglioform enlargement 

 and goes to Meckel's ganglion. 



2. The small petrosal branch is given off at the ganglioform enlargement 

 or a very short distance beyond it and passes to the otic ganglion. 



3. A small branch, the tympanic, is distributed to the stapedius muscle. 



4. The chorda tympani passes through the cavity of the tympanum and 

 joins the lingual branch of the inferior maxillary division of the fifth, as it 

 passes between the two pterygoid muscles, with which nerve it becomes 

 closely united. 



5. Opposite to the point of origin of the chorda tympani, a communicat- 

 ing branch passes between the facial and the pneumogastric, connecting these 

 nerves by a double inosculation. 



The five branches above described are given off in the aquseductus Fal- 

 lopii. The following branches are given off after the nerve has emerged 

 from the cranial cavity : 



1. Just after the facial has passed out at the stylo-mastoid foramen, it 

 sends a small, communicating branch to the glosso-pharyngeal nerve. Thi& 

 branch is sometimes wanting. 



2. . The posterior auricular nerve is given off by the facial, a little below 

 the stylo-mastoid foramen. Its superior branch is distributed to the re- 

 trahens aurem and the attollens aurem, In its course this nerve receives a. 

 communicating branch of considerable size from the cervical plexus, by the 

 auricularis magnus. It sends some filaments to the integument. The in- 

 ferior, or occipital branch, the larger of the two, is distributed to the occipi- 

 tal portion of the occipito-frontalis muscle and to the integument. 



3. The digastric branch is given off near the root of the posterior auricu- 

 lar. It is distributed to the posterior belly of the digastric muscle. In ita 

 course it anastomoses with filaments from the glosso-pharyngeal nerve. 

 From the plexus formed by this anastomosis, filaments are given off to the 

 digastric and to the stylo-hyoid muscle. 



4. Near the stylo-mastoid foramen, a small branch is given off, which is 

 distributed exclusively to the stylo-hyoid muscle. 



5. Near the stylo-mastoid foramen, or sometimes a little above it, a long, 

 delicate branch is given off, which is not noticed in many works on anatomy. 

 It is described, however, by Hirschfeld, under the name of the lingual branch. 

 It passes behind the stylo-pharyngeal muscle, and then by the sides of the 



