116 INNERVAT10N. [CHAP. xx. 



upon it. This is the ganglion jugulare, discovered by Ehrenritter. 

 Beyond this, and lodged in a fossa in the side of the jugular foramen, 

 is another ganglion which involves all the fibres of the nerve; this is 

 the ganglion petrosum, originally described by Andersch. After its 

 escape through the jugular foramen, the glosso-pharyngeal descends 

 by the side of the pharynx, between the stylo-glossus and stylo-pha- 

 ryngeus muscles, and in the region of the tonsil breaks up into its 

 terminal branches. 



From the ganglion of Andersch, a nerve passes off, and enters 

 the cavity of the tympanum, occupying a groove upon the surface 

 of the promontory beneath the lining membrane of the tympa- 

 num. This branch, lately called the branch of Jacobson, al- 

 though described by Andersch and Winslow, divides into six 

 filaments, which form the tympanic plexus or anastomosis. These 

 filaments are as follow: 1. To the membrane of the fenestra 

 ovalis. 2. To that of the fenestra rotunda. 3. To the carotid 

 plexus in the carotid canal. 4. To the mucous membrane of the 

 Eustachian tube. 5. An anastomotic branch, which passing through 

 the upper wall of the tympanum unites with the greater superficial 

 petrosal nerve. 6. An anastomotic branch to the otic ganglion, 

 called by Arnold the lesser superficial petrosal nerve. 



Near the petrosal ganglion the glosso-pharyngeal nerve forms 

 anastomoses with the facial and the par vagum. 



The following are the terminal branches of the glosso-pharyngeal 

 nerve. 1. A branch to the digastric and stylo-pharyngeal muscles. 



2. Three or four carotid filaments which descend along the internal 

 carotid artery, and may be traced as far as the bifurcation of the 

 common carotid. These nerves anastomose with others from the su- 

 perior cervical ganglion, and form a plexus round the carotid artery. 



3. Tonsillitic branches, which are numerous, and along with nerves 

 from the vagus and from the superior cervical ganglion of the sym- 

 pathetic, form a plexus beneath the mucous membrane in the vi- 

 cinity of the tonsil, which is called the pharyngeal or tonsillitic 

 plexus. Some of the branches of this plexus are distinctly connected 

 with the mucous membrane, others with the muscular fibres of the 

 pharynx. 4. Pharyngeal branches, which are distributed to the 

 mucous membrane of the wall of the pharynx . 5. Lingual branches ; 

 these are given to the mucous membrane at the base and side of 

 the tongue, and one may usually be traced into the soft palate. 



From the preceding statement it appears that the distribution of 

 the glosso-pharyngeal nerve is chiefly, if not exclusively, to sentient 

 surfaces. Even its tympanic branch is connected with the lining 



