648 THE NERVOUS SYSTEM. 
arteries, in its course to the side of the pharynx. It sweeps round the stylo- 
pharyngeus muscle and the stylo-hyoid ligament, and disappears beneath the 
hyoglossus muscle, to reach its ter- 
\ Cala 582 mination in the tongue. 
\ PPh nen The branches of the nerve may 
\ ee a a 
Aur. WW \W/ VA Ty. Plex of be classified in three series, accord- 
< ili?” ing to their origin—(i.) in the 
i 
jugular foramen; (i1.) in the neck ; 
(i1.) in relation to the tongue. 
In the jugular foramen there 
are two enlargements upon the 
trunk of the nerve—the jugular 
and petrous ganglia, The jugular 
ganglion (2. superius) is small, does 
not implicate the whole width of 
the nerve, and may be fused with 
the petrous ganglion, or even ab- 
sent altogether. No branches arise 
from it. 
The petrous ganglion (xg. petro- 
sum) is distinet and constant. It 
is placed upon the nerve at the 
lower part of its course through the 
jugular foramen. 
Branches and Communications of 
4 Uy / {aa the Petrous Ganglion. —Thetympanic 
LU sears branch (n. tympanicus, Jacobson’s 
nerve) is the most important offset 
from this ganglion. It passes 
G.Ph, Glosso-pharyngeal nerve; J, Jugular, and P, Petrous through a small canal a the bridge 
ganglia; Ty, Tympanic branch (Jacobson’s nerve) ; of bone between the jugular fora- 
Ty.Plex, Tympanic plexus; Fa, Root from geniculate yyen and the carotid canal to reach 
Serve to the otic ganglion; SD.P, Small deep petrosal the cavity of the tympanum, where 
nerve; I.C, Internal carotid artery ; Va, Pneumogastric 1 breaks up into branches, to form, 
che 2M Sian ee Sere ea Sy, alongwith branches from the carotid 
etc a reer Ph, Di Wn eal rasa plexus of the sympathetic on the 
vagus ; E.C, External carotid artery ; Ph.Pl, Pharyngeal internal carotid artery (small deep 
pene ete ee eee ee meee 3 Se hae petrosal nerve), the tympanic plexus 
Ton, Tonsil : S.Pal, Soft ae CHG, Gone etelceeter for the supply of the AO lining 
G.H, Genio-hyoid ; Hy, Hyoid bone. of the tympanum, mastoid cells, and 
Eustachian tube (Fig. 463, p. 645). 
The fibres of the tympanic branch of the glosso-pharyngeal nerve become reunited 
to form, by their union with a small nerve ‘from the geniculate ganghon of the facial 
nerve, the small superficial petrosal nerve in the substance of the temporal bone. This 
passes forwards through the temporal bone, and eventually joins the otic ganglion. 
igi 
re 
Fic. 466.—ScCHEME OF THE DISTRIBUTION OF THE GLOSSO- 
PHARYNGEAL NERVE. 
Besides forming the tympanic branch, the petrous ganglion of the glosso-pharyngeal 
nerve communicates with three other nerves—(1) with the superior cervical ganglion of 
the sympathetic ; (2) with the auricular branch of the pneumogastric ; and (3) sometimes 
with the ganglion of the root of the pneumogastric. 
In the neck the glosso-pharyngeal nerve gives off two branches. (1) As it 
crosses over the stylo-pharyngeus muscle it supplies the nerve to that muscle, 
which sends fibres through it to reach the mucous membrane of the pharynx. (2) 
The pharyngeal branches of the nerve supply the mucous membrane of the pharynx 
directly, after piercing the superior constrictor muscle, and indirectly, after joming, 
along with the pharyngeal offsets from the pneumogastric and the superior cervical 
ganglion of the sympathetic, in the formation of the pharyngeal plexus. 
The terminal branches of the nerve supply the mucous membrane of the 
tongue and adjacent parts. A tonsillitic branch forms a plexus (circulus tonsillaris) 
