THE OPHTHALMIC GANGLION. 
49 
nerve says, '‘Almost at its commencement we observe the fila- 
ments that help to form the ophthalmic ganglion. They are 
more numerous and more easily traced in some of our domestic- 
ated animals than in others, and the ganglion itself is differently 
developed ; but for what purpose it is not easy to determine. 
It is comparatively larger in the ox than in the horse, and sends 
more nervous filaments to the iris. Four distinct ones may be 
traced in the ox, but seldom more than two in the horse or dog. 
To these filaments others of the ophthalmic that have not passed 
the ganglion afterwards join themselves, so that the ciliary 
nerves are also minute compound ones of motion and sensation*.” 
The best account however of this, and somewhat differing 
from all the others, is given by Dr. Quain. He considers the 
ganglion as a little centre of nervous influence, a brain, as it 
were, of itself, and the filaments which the others describe as 
composing, he speaks of as branches given out from it. “ It 
lies,” says he, " within the orbit, about midway between the 
optic foramen and the globe of the eye, and enclosed between 
the external rectus muscle and the optic nerve ; it is exceedingly 
small, and not easily found, owing to its being embedded in the 
soft adipose tissue which fills up the interstices between the 
different parts within the orbit. 
Its branches are the following : from its anterior border from 
sixteen to twenty delicate filaments issue, which proceed forwards 
to the surface of the sclerotica, and pierce it through minute 
foramina. These are the ciliary nerves. In their course to the 
globe of the eye they are joined by one or two filaments derived 
from the nasal nerve, but they do not form a plexus or an inter- 
lacement ; they become, however, dispersed or divided into two 
fasciculi, one above and the other below the optic nerve, the 
latter being the more numerous. They pass along between the 
choroid membrane and the contiguous surface of the sclerotica, 
lodged in grooves in the latter, and on reaching the ciliary liga- 
ment, they pierce it, some few of them appearing to be lost in 
its substance, while all the rest pass inwards and ramify in the 
iris. 
From the posterior border of the ganglion, which seems as if 
terminated by two angles, two branches issue, of which one 
passes backwards and upwards to the nasal branch of the 
ophthalmic nerve, and which appears to be the medium of com- 
munication between the ganglion and the rest of the ganglial 
system, by being prolonged to the carotid plexus : the other 
reflected branch is shorter than the preceding, and passes down- 
* Veterinarian, vol. vii, p. 124. 
VOL. IX. 
ii 
