467 
THE GREAT ORGANIC NERVE. 
the vertebral artery, and more particularly the axillary artery, 
on the trunk of which it cannot be mistaken, and on the branches 
of which it may be long followed. It begins also to be more 
evident on the carotids, and forms on them numerous plexuses, 
interspersed with ganglions, and which seem to be the souices 
of new radiations; and these run along the great vessels to the 
liGcirt* 
The Posterior Cervical Ganglion• —As it enters the thorax, or 
under the first dorsal vertebra, this nerve enlarges again, but not 
to the same degree as at the superior ganglion. Here we briefly 
trace some important branches—one of considerable size to the 
seventh (sixth) cervical nerve, not, as our best veterinary ana.- 
tomist asserts, on account of “ the mediate connexion which it 
thus has with the five anterior cervical nerves,” because it has 
had direct communication with them in its passage down the 
neck ; but because a plexus of spinal nerves is here beginning 
to be formed for the supply of the fore extremities, and this 
nerve is called upon to contribute its influence whatever it may 
be. There are branches to the last cervical—to the first and 
second dorsals—a plexus about the root of the trachea—fibrils 
to the oesophagus—more to the recurrent, and, chief of all, the 
cardiac plexus, given to, and plainly ramifying over, the great 
vessels of the heart. I have not time to enumerate the ramifi¬ 
cations and plexuses which are here formed ; they are so nu¬ 
merous and complicated, that no vessel, of the heart or lungs, or 
even anv portion of a vessel, should be without this nervous 
tunic. . 
Division within the Thorax.— All these are ramifications from 
this nerve, the trunk of which has entered the thorax, and runs 
along the spine under the articulations of the ribs; but it soon 
divides on each side. The proper great organic pursues its 
course under the articulations of the vertebrre; and, between the 
heads of each rib, it swells out into a small ganglion, from each 
of which filaments proceed to the intercostal nerve, going prin¬ 
cipally to the motor branch of it, and receiving filaments from 
it: and thus it reaches the diaphragm, under the crus of which 
it passes into the abdominal cavity. 
The Splanchnic Nerve.— Varying in different subjects, fibres 
begin to be given off from the trunk of the gieat oiganic nei\e 
about the 5th, 6th, and 7th rib; and these unite and form a con¬ 
siderable branch on each side, which descends some distance 
from the spine, and pursues its course over the libs, and under 
the pleura, to the diaphragm, and bearing the name of the 
greater splanchnic nerve. It also enters the abdomen undei the 
crus of the diaphragm. Another smaller branch is given off 
