THE MEDULLA OBLONGATA. 
39 
and the nerve is composed of minute fibrils — not proceeding bodily 
from the cord — and arising in a line; these are the characters 
of a nerve of motion ; but before, or as they unite, they pass 
through or form a ganglion — the character of a nerve of sensa- 
tion — and these distinct properties are possessed by distinct 
fibrils, the more probable conjecture, or each fibril has the power 
of exciting motion or conveying sensation. 
The Course of the Nerve . — This ganglion being formed, the 
nerve pierces the dura mater, and although it makes its exit from 
the skull through the same foramen with the tenth, is altogether 
distinct and separate from it ; for there is a fibro-cartilaginous 
septum, or division in the foramen lacerum, which prevents them 
from being in contact with each other. The ganglion is formed 
during the passage of the nerve through this foramen, and is 
sometimes called the petrous ganglion , from its proximity to the 
petrous bone. Beside the principal destination of this nerve to 
the pharynx and the tongue, it communicates with various parts. 
Scarcely is the ganglion formed ere a filament from it enters a 
canal that leads to the cavity of the tympanum of the ear. It 
has no connexion, however, with the mechanism of the ear, but 
it takes this singular course in order to unite two of the branches 
into which it divides with the spheno-palatine ganglion, and that 
the third may be conveyed to the back part of the palate, over 
which it is distributed. If our patients could tell us the seat of 
many of their pains, they would perhaps complain bitterly of 
the ear-ach, in some of the sore-throats to which they are so 
subject. This and the evident and dreadful affection of the 
fauces in the rabid dog are well explained by this anastomosis. 
The spheno-palatine ganglion belongs to the ganglionic system ; 
and it is easy to imagine that there will be many anastomoses 
between these two divisions of the organic nerves. Accordingly, 
we find that there are anastomoses with the tenth pair, and with 
several branches of the ganglial system, and also with the facial 
or seventh pair, a portion of which we shall claim as appertain- 
ing to the organic nerves. Many branches pass inwards, and 
ramify upon the pharynx, contributing with those from the tenth, 
which will be presently described, to form the intricate pharyngeal 
plexus. There it meets, and supplies with influence the stylo- 
pharyngeus muscle; assisting in the dilatation of the pharynx by 
drawing it upwards and backwards, and likewise also giving 
power to the constrictors of the fauces, and sending not a few 
fibrils to direct the action of the epiglottis. At length.it gives 
some branches to the root and substance of the tongue, to the 
hyo-glossus muscle which assists in retracting and depressing the 
