THE GREAT SPINAL ORGANIC NERVE. 
61 
Branches to the internal Carotid. — It is in this upper part of 
its course that the great spinal organic begins to display its con- 
nexion with the circulatory system. At the bifurcation of the 
carotid artery, and mostly connected with the internal carotid, 
we find numerous branches — a plexus of filaments — from this 
nerve. We are not yet justified in forming any decisive conclu- 
sion as to the intention of this nervous distribution; but one 
thing we do know, — that the arteries possess a muscular tunic of 
great power, and on which depends, to a considerable extent, 
and at a distance from the heart, almost entirely, the natural 
and the morbid circulation of the blood within them ; that from 
no other source, except in the most circuitous and indirect, way, 
can we trace any nervous filaments to the arteries, that do not 
proceed from this or the ganglionic nerve. When we find 
this organic motor nerve — the motor one, par excellence, almost 
at its origin — so plentifully distributing its filaments on the 
carotid, and especially on the interior carotid — the artery of the 
brain — the vessel through which it is so necessary, for the dis- 
charge of the functions of the brain, that the blood should flow 
in an equable stream, and to prevent the disturbance of which 
there are such beautiful provisions in the bony structure of cer- 
tain parts of the cranium, and the strange tortuosity of the course 
of the vessels — when, I say, we reflect on all these coincidences, 
we cannot help suspecting — I will not use a stronger word at pre- 
sent — that this great spinal organic nerve is much concerned in 
regulating the circulation of the blood through its devious path. 
We shall have stronger proof of it immediately. 
The Connexion between the two great Organic Nerves. — We 
pursue the course of this nerve down the neck, in the same 
sheath with the ganglionic nerve, and in company with the 
carotid artery. For a considerable way there are no branches 
given to the neighbouring parts, for there are few that are ne- 
cessary to, or that can be well employed in, the purposes of 
organic life ; but there are almost innumerable filaments of com- 
munication between this nerve and the ganglionic one, not, 
perhaps, so much taken into consideration as they deserve to be, 
but evidently allying the two nerves together for one common 
purpose, although certainly not rendering them precisely iden- 
tical ; and preparing them, by the mutual interchange of influ- 
ence, for the important functions which they are about to discharge. 
The cardiac Branches. — When this nerve is approaching to 
the thorax it gives off a branch on either side, larger and more 
complicated on the right side than on the left; and these pursue 
their course to the origin of the great bloodvessels, and unite 
with and help to compose the cardiac plexus, between the arch 
