Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 4: Pla [corr.: Ple] - Wri
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29465/560/
550 
SEVENTH PAIR OF NERVES. 
spheno-palatine, and the lesser (i) to the otic 
ganglion : the first of these Morganti has de¬ 
picted receiving a filament (k), which comes 
from the facial, and in its course to the pe¬ 
trosal nerve passes over the ganglion without 
joining it. The second or lesser of the two 
appears to be derived solely from the ganglion. 
3. A large branch (m) which forms the great 
bulk of the chorda tympani ; but, in order to 
this, is also joined by one or two filaments («) 
from the facial nerve, which accompanies it in 
the Fallopian canal. 4. Branches (/) which 
passing downwards are lost in the trunk of 
the portio dura. 
The annexed diagram, {fig. 405.) with the 
letters attached to it, will assist the reader in 
following this otherwise intricate description. 
It is taken from a drawing by Morganti in 
the essay referred to ; but it has been reduced 
in size and simplified, so as better to allow 
of its introduction here. 
The same author has examined into the 
comparative anatomy of the ganglion and the 
nerves connected with it in many of the 
other mammalia, as the dog, calf, lamb, mule, 
and dormouse. 
The general results of these examinations 
abundantly verify his description of the ar¬ 
rangement in the human subject. Indeed, 
these animals offer by far the most favourable 
subjects for exemplifying the truth of the 
preceding description, being, as Morganti 
remarks, natural preparations of these parts. 
Not only is the dense and intimate^ adherent 
sheath of fibrous tissue, which is present in 
man, much looser in the ganglion and nerves 
of these animals, but the position of this body 
with respect to the nerve is considerably 
altered. The much less marked anterior 
bend of their portio dura occurs at some 
little distance from the hiatus Fallopii ; and 
the ganglion, which is in immediate proximity 
to this aperture, is thus no longer geniculate 
in its position, being removed from the knee 
of the facial. Hence it is, as it were, out of 
the way of the facial branches, and ceases to 
be entangled amongst them, as in the human 
subject. 
The author of this article can bear testi¬ 
mony to the accuracy of these statements; 
indeed, any one may easily verify them for 
himself, in most of these animals, with scarcely 
more trouble than removing the brain and 
osseous roof of the Fallopian canal, and then 
stripping off the comparatively lax neuri¬ 
lemma from the subjacent ganglion and 
nerves. The accompanying sketch {fig. 406.) 
was taken from the left side of a sheep’s head. 
With as little artificial separation as possible, 
it represents the arrangement of the ganglion 
and nerves in situ, especially the manner in 
which the trunk of the portio intermedia 
crosses the facial nerve without joining it, 
and the apposition or proximity, without 
mingling, of the ganglion and the latter nerve. 
The varieties of arrangement which obtain 
in the different animals whose nerves Mor¬ 
ganti examined, are chiefly, as might be 
expected, differences in the degree of inter¬ 
lacement of the adjacent nerves. In parti¬ 
cular, that of the portio intermedia with the 
Fig. 406. 
Auditory, Facial, and Intermediate Nerves of a Sheep 
as seen in situ. Magnified about 2^ diameters. 
a, portio dura; b, portio intermedia; c, portio 
mollis ; e, origin of the superficial petrosal nerves ; 
f, chorda tympani ; g, geniculate ganglion. 
vestibular nerve is sometimes so complete 
and intricate, as to render it in such instances 
difficult to ascertain from their examination 
only, whether the former of these nerves 
gives branches to the latter, or, vice versa, 
this to that. In the mule, he exhibits a fila¬ 
ment from the facial to the ganglion ; but 
thinks this a possible restitution of one or 
both of the two previously given to it by the 
portio intermedia. 
The general anatomical conclusion to be 
drawn from these details is, that the facial 
nerve—as implying in this term both the 
portio dura and the portio intermedia— 
arises by two roots. Upon the smaller of 
these a ganglion is formed, while the latter is 
entirely devoid of such a structure. The 
branches of the facial nerve in the Fallopian 
canal are mixed nerves, being formed partly 
by filaments from the ganglion ; partly also 
by filaments from the aganglionic root ; the 
latter being in considerably lesser numbers. 
And the trunk of the facial itself, beyond the 
ganglion, is also a mixed nerve, since, although 
by far the greater part of its bulk consists of 
fibres from the greater root, yet it also con¬ 
tains one or two filaments which come from 
the ganglion. The analogy of this arrange¬ 
ment to that of the spinal nerves is sufficiently 
obvious, and will be hereafter again re¬ 
ferred to. 
It deserves to be mentioned in this place, 
that many other accounts of the arrangement 
of these nerves might easily have been added 
from various authors, but that all of them are 
more or less at variance, both with the above 
description by Morganti, and with each other. 
It has seemed fit, however, to assign these a 
very subordinate position in the present short 
article, since the verification of a ganglion 
belonging exclusively to the portio intermedia 
includes not only the denial, but I think we 
may add the disproof, of many of these 
descriptions. So far as our knowledge of the 
structure of ganglia at present extends, and 
whether the late brilliant researches of Ru¬ 
dolph Wagner* apply universally or not, we 
are at least justified in viewing with great 
* Handwörterbuch der Physiologie. Sieben¬ 
zehnte Lieferung. Artikel “ Sympathischer Nerv 
Ganglienstruktur und Nervenendigung.”
        

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