Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 3: Ins-Pla
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29464/768/
721r 
PHYSIOLOGY OF THE NERVOUS SYSTEM. 
ference to the locomotive actions, and the great 
developernent of the vesicular nervous matter 
in these regions betokens the frequent and 
energetic evolution of the nervous force. All 
the structural arrangements necessary for this 
purpose are found in the antero-lateral columns. 
The posterior columns come into exercise in 
balancing the trunk and in harmonizing its 
movements with those of the lower extre¬ 
mities. 
Some support is obtained for this view of the 
function of the posterior columns from the phe¬ 
nomena of disease. In many cases, in which 
the principal symptom has been a gradually in¬ 
creasing difficulty of walking, the posterior 
columns have been the seat of disease. Two 
kinds of paralysis of motion may be noticed 
in the lower extremities, the one consisting 
simply in the impairment or loss of the 
voluntary motion, the other distinguished by 
a diminution or total loss of the power of co¬ 
ordinating movements. In the latter form, 
while considerable voluntary power remains, 
the patient finds great difficulty in walking, and 
his gait is so tottering and uncertain that his 
centre of gravity is easily displaced. These 
cases are generally of the most chronic kind, 
and many of them go on from day to day with¬ 
out any increase of the disease or improvement 
of their condition. In two examples of this 
variety of paralysis I ventured to predict dis¬ 
ease of the posterior columns, the diagnosis 
being founded upon the views of their func¬ 
tions which I now advocate; and this was 
found to exist on a post-mortem inspection; 
and in looking through the accounts of re¬ 
corded cases in which the posterior columns 
were the seat of lesion, all seem to have com¬ 
menced by evincing more or less disturbance 
of the locomotive powers, sensation being af¬ 
fected only when the morbid change of struc¬ 
ture extended to and more or less involved the 
posterior roots of the spinal nerves. 
Bedingen put forward the opinion that the 
anterior columns of the spinal cord influenced 
movements of flexion, and the posterior co¬ 
lumns those of extension; to the grey matter 
he assigned the office of propagating sensitive 
impressions to the brain ; and the lateral co¬ 
lumns, according to him, exercised an influ¬ 
ence upon the organic functions of nutrition 
and circulation. 
The views already referred to respecting the 
grey matter show that it cannot be regarded as 
devoted exclusively to one function of the ner¬ 
vous system ; nor can it be viewed as capable 
of taking its part in nervous actions without 
the white or fibrous matter. 
Valentin adduces some experiments not un¬ 
favourable to the supposition that the nerves of 
extensor muscles pass towards the posterior part 
of the cord, and those of the flexor muscles to 
the anterior part. He found that if, in frogs, 
the posterior surface of the cord on one side of 
the posterior median fissure in the region of the 
second or third vertebra were irritated by the 
point of a needle, the anterior upper extremity 
of the same side was extended and drawn 
backwards. When the anterior surface was 
irritated, the limb was drawn forwards to the 
head. Irritation of the posterior column in 
the region of the sixth vertebra and below it 
caused extension of the posterior extremities, 
but they were thrown into flexion by irritation 
of the anterior-columns. 
These are remarkable results ; they need, 
however, the confirmation of other observers. 
If they be correct, the fact of the connection 
of the nerves of extensor muscles with the 
posterior columns has an interesting relation 
with the supposed locomotive function, for 
there can be no doubt that movements of ex¬ 
tension contribute largely to the ordinary 
attitudes and to the various modes of pro¬ 
gression. 
Valentin refers to cases in which the anterior 
columns having been the seat of tumor or of 
softening, more or less permanent flexion of the 
lower limbs had ensued. These cases do not 
favour his view unless he can show that the 
lesion in all the cases was of the irritant kind, 
inducing a spasmodic contraction of the flexor 
muscles; for if the lesion be of a paralysing 
kind, the effect would be to paralyse the flexor 
muscles and allow the extensors full sway. The 
explanation of the flexed state of ' limbs in 
cases of this kind is probably to be derived 
from a chronic state of contraction induced 
in the muscles themselves by the lesion of the 
nervous centre, and the state of flexion is as¬ 
sumed rather than extension in consequence of 
the predominance of flexor muscles over ex¬ 
tension. 
Sir Charles Bell’s doctrine, which assigned 
to that portion of the cord which is interme¬ 
diate between the roots of the nerves, (his 
middle column, ) a special power over the move¬ 
ments of respiration, has long ceased to gain 
attention from physiologists. It wanted the 
support of anatomy. The so-called middle 
column had no defined limits, nor could it be 
proved that any respiratory nerves were con¬ 
nected with this region of the cord, excepting 
a few fibres of the spinal accessory nerve. The 
distinct anatomy of a respiratory system of 
nerves existed only in the imagination of the 
inventor of the doctrine. It could not be 
shown by experiment that the so-called nerves 
of respiration had any special respiratory func¬ 
tion beyond that which they exercised as the 
motor nerves of certain muscles. And among 
the nerves which Sir C. Bell had classed toge¬ 
ther as nerves of respiration, were some which 
certainly had no necessary connection with that 
function. Of these the portio dura and the glosso¬ 
pharyngeal are examples. 
Influence of the spinal cord upon the organic 
functions.—The influence of the spinal cord 
upon certain organic functions has engaged a 
large share of the attention of experimental 
physiologists. It has been said to have a very 
direct control over the functions of circulation, 
calorification, secretion, especially that of the 
kidneys. 
If it can be shown that the organs concerned 
in these functions receive several nerves from 
the spinal cord, then we do not stand in need 
of vivisections to indicate to us that the
        

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