396 SPECIAL ANATOMY. 



ticus and fossa jugularis) to the inner wall of the tympanum, is 

 surrounded by a thin ganglionic mass (ganglwlum tympan.) 

 receives a filament from plex. caroticus, and gives a branch to 

 thefenestrcz rotund, and ovalis. Below the last the trunk bends 

 round, forwards and downwards, passes through tuba Eustachii, 

 perforates its cartilage, and terminates in the glands about its 

 orifice. Two branches, besides, pass off on a plane with the 

 fenestra ovalis. 



a. JN. petrosus profundus minor, passes through a canal of the 

 septum between tuba Eustachii and canal, caroticus in the 

 last to the plex. carotic., where it unites with ram. prof. n. 

 Vidian. 



b. Ram. communicans n. petrosi-superficialis minoris, passes 

 in a canal behind the tubce. Eustachii upon the anterior sur- 

 face of the petrous bone to n. petros. superf. minor (see 

 nerv.facialis), which passes through for am. spinos. to gangl. 

 oticum. 



(Plexus tympanicus major, Jacobson's anastomosis is princi- 

 pally formed by a., lies upon the internal wall of the tympanum, 

 supplies the mucous membrane and osseous substance, and is 

 probably in connexion with the chorda tympani.) 



3. Ramus pharyngeus, divides into from two to three branches, 

 which form, with those of n. vagus, the plex. pharyngeus, and 

 supply m. constrictor super, and med. and the posterior part of 

 the pharynx. 



4. Ramus lingualis, the nerve of taste, the continuation of the 

 trunk, passes in a curve, convex behind, from the carotis interna 

 to the root of the tongue, giving, in this course, branches to m. 

 stylo-pharyngeus, which lies before it, to the tonsils above, to the 

 mucous membrane of the root of the tongue, where it anastomoses 

 with n. maxillaris inferior. In the root of the tongue it divides 

 immediately into an external branch for the mucous membrane of 

 the border and the inferior surface, and an internal branch for the 

 posterior third of the mucous membrane, as it forms a plexus about 

 the foramen caecum. Both unite with n. maxillar. inferior and 

 trigemini. 



642. X. N. Vagus s. pneumogastricus, the Vagus nerve. 



Origin : with from twelve to sixteen filaments (united into from 

 six to eight fasciculi) from the central columns of medulla oblong. 

 between corp. olivare and restiforme. Course : under the cere- 

 bellum obliquely downwards, forwards and outwards to the ante- 

 rior part of iheforam. jugulare. It here lies in an especial sheath 



