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'¡4 O B S E R V A T I O N S ON THË
is the cafe of the thoracic ganglia of the fympathetic nerve, the nerve at
the fide appears to confift of cords, which divide into afcending and defcending
cords, that are combined with the cords which compofe the upper
and under nerves
If branches, fuch as the rami fplanchnici, are fent off from a ganglion
in which fuch defcending, afcending, and lateral, or tranfverfe nerves meet,
the branches feem to receive threads from all the nerves which enter the
ganglion. .
E T . VI.
FROM tiiefe feveral fafts, I apprehend we may draw the following conclufions.
i'/?;/?, Several branches of the nerves, which enter a ganglion, run upon
its furface, feparating from each other, and joining again, fo as to form
new combinations of threads at the other end of the ganglion.
Second/j, When we cut a ganglion, we are fo far from finding that the
courfe of the nerves is interrupted within it, or that it is a fubftance totally
different in its nature from the nerves that enter it, that we are able to
trace, in every part of the ganglion, nerves diftinguifliable by fuch folds
or joints as are feen in them in all other places.
Thirdly^ In the fubftance of the ganglion, we fee nervous cords leading
from any one nerve, connected to the ganglion, to the greater number of,
if not to all, the other nerves conneâed with it, from which we may conclude,
that various other combinations of the nervous threads take place
within it "f".
Fourthly^
' Sec Tab. XS. Fig. i. B. Tab. XXII. Fig. 3. 4. F. K.
t Zinn, M. de I'Acad. de Beriin 1753, P- '38- fays. ' H me paroit extremement probable,' that the
nervous threads in ganglia are intermixed ; but this opinion, with him and many others, was a mere
hypothefis, not founded on afhial obfervation.
N E R V O U S S Y S T E M . S i
Fourthly, It appears very difficult, in many inftances, to diftinguiih all
the nerves which enter a ganglion, from thofe which are fent off from it.
And, of courfe, it is difficult, or impolTible to determine all the fources
from which any branch fent off from the ganglion is derived. For example,
akhough the nerves at the upper end of a thoracic ganghon of the
great fympathetic nerve are compcfed chiefly of defcending branches, and,
in like manner, the two nerves which tie it to the proper dorfal nerve, are
chiefly derived from the dorfal, yet there feem to be afcending branches
from the nerves below, and others fent outwards, from the ganglion, to
the proper dorfal nerve; and, probably, the fplanchnic nerves receive
threads from all thefe fources.
Fifthly, The nerves which iflTue from ganglia feem, as authors * have alledged,
to be more bulky than the nerves we may fuppofe to enter the gangha;
yet I have not been able to difcover that the coats of the nerves going
out were thicker, or different from the coats of the nerves going into
the ganglia: Hence there is juft reafon to fuppofe, that nervous matter is
furniflied by the ganglia.
Sixthly, To ftrengthen the fuppofition that the ganglia are to be confidered
as fources of nervous matter and energy, I would obferve.
That the yellowilh or brownifli matter of ganglia has numerous veffels
conveying red blood, as in the cortical fubftance of the brain, difperfed
upon it: That its colour, efpecially in man, very much refembles that of
the cortical fubftance of the brain; That, in feveral children, in whom the
brain had either been originally imperfed, or compreffed by accident, its
colour and confiftence ftill more clofely refembled that of a ganglion. As
to the greater hardnefs of the ganglia than of the cortical fubftance, which,
t o
• Meckel, M. de i'Acad. a Berlin, 1749, p. 95.
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