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5° O B S E R V A T I O N S ON THE
C H A P T E R XIX.
Of the Ganglia of the Nerves.
T . I.
" F WOULD begin here wi t h again obferving an univerfal overfight of authors
in tlieir defcription of the gangha of the fpinal nerves. They defcribe
t h e f e as formed after the anterior and pofterior fafciculi of nervous fibres
f r om the ipinal marrow are uni ted; fo that every nervous fibre from the
fpinal mar row, is fuppofed t o pafs through a ganglion. Inftead of this, I
have obferved, that the pofterior fafciculus onl y of the fpinal nerve enters
i n t o the ganghon; and that authors had been deceived, by not having flit
open the external coat of thefe nerves *.
One half, therefore, of all the nerves of the mufcular organs of the trunk
of the body, and one half of the nerves of the arms and legs, do not pafs
t h r o u g h ganglia.
T . I I .
AUTHORS fuppofe that the olfai loiy, the optic nerves, the fourth, fixtll,
feventh, eighth, with its acceffory, and the ninth pair, are wi thout j
But, as the fixth pair, portio dura of the feventh, the eighth and the
n i n t h pairs, are conneited by nervous filaments to the gangha of the great
fympathetic nerve, we lhall foon find that there may be fome reafon for fuppofing
that part of them likewife paffes t h r o u g h thefe gangha, as we cannot
pretend to judge of the courfe of the nerves f rom obferving the angles they
f o rm wi t h their trunks, the courfe of many nerves being retrograde.
S E C T ,
• See Tab. X. N, O, P, CI. And Tab. XI. N, O, P, Q.
N E R V O U
HOWEVER diíFerent from each other the ganglia feem in iliape and fize, in
different parts, and although, in the progrefs of the great fympathetic
nerve, the number, and, of courfe, the fize of each, varies in dilTerent perfons,
I have found, after accurately examining the principal ganglia in man
and in the ox, and particularly the lenticular ganglion of the eye, the ganglion
in the trunk of the fifth pair the cervical, thoracic, and fcmilunar
ganglia of the great fympathetic, the ganglion in the pofterior fafciculus of
t h e fpinal nerves, that they all agree in their general ftrudure, which I
fhall next defcribe, as it appears t o the naked eye, or when viewed with a
common magnifying glafs.
I n inveftigating this fubjeét, I was enabled to trace the nerves in the
ganglia, by attending to their folds or joints, when it woul d have been impoflible,
from any other circumftance in their ftrudure, to have diftinguillicd
them.
I have akeady obferved, that the nerves of an ox, or other large animal,
are larger than the nerves of a man, although his brain be fznaller. The
fize of the gangUa bears a p ropor t ion to that of the nerves.
I n the next place, although the fize of the ultimate fibrils of which the
nerves are compofed, is, perhaps, not larger in the ox than in man; and alt
h o u g h , of courfe, the number of ultimate fibrils is in proportion to the
bulk of the nerves; yet the funiculi, or cords into which thefe are colle<£ted,
are larger in the ox. Hence I found, that I could trace the nerves farther
and more diftin£lly in the ox than in man, and more eafdy and certainly
difcover the texture of the ganglia.
A u t h o r s