“PLYSIOLOGY OF TIE NERVOUS SYSTEM. 
posterior, and the anterior roots solely in the an- 
terior columns. Nothing, however, is more cer- 
tain than that both roots are implanted in the 
antero-lateral columns, and it is extremely doubt- 
ful that the posterior roots have any connection 
at all with the posterior columns. Hence, as far 
as anatomy enables us to judge, this distinction 
of function between the two columns cannot be 
admitted. On the contrary, anatomy indicates 
that the antero-lateral columns are compound 
in function. Their connection with the 
corpora striata and optic thalami, and with 
the mesocephale through the anterior pyramids 
and fasciculi innominati, their reception of 
both the anterior and posterior roots, and their 
size in each region of the cord bearing a direct 
proportion to that of these roots, denote that 
these columns with the associated vesicular 
matter are the seat of the principal nervous 
actions, both mental and physical, with which 
the cord is concerned. 
This view of the office of the antero-lateral 
columns is confirmed by comparative anatomy, 
which shows that the bulk of the organ or the 
variety in the size of its various parts depends 
mainly on these columns. 
Pathological ohservations are also in favour 
of this doctrine. They distinctly denote that 
lesion of the antero-lateral columns impairs the 
sensitive as well as the motor power to an extent 
proportionate to theamountoflesion. Itis worthy 
of note, however, that while a slight lesion of 
the cord appears sufficient to impair or destroy 
the motor power, it requires a considerable ex- 
tent of injury or disease to impair in any very 
marked degree the sensitive power. Some 
lesions of these columns destroy the physical 
nervous actions of the diseased or injured part 
of the cord—augmenting those of the portion 
below the seat of lesion, doubtless by increasing 
its polarity ; this is seen especially in cases of 
injury tothe cord by fractures or dislocations 
of the spine. 
Direct experiments afford no aid in deter- 
mining the functions of the columns of the 
cord. Attempts to expose this organ either in 
living or recently dead animals are surrounded 
with difficulties, which embarrass the experi- 
menter and weaken the force of his inferences, 
if, indeed, they afford any premises from which 
a conclusion may be drawn. The depth at 
which the cord is situate in most vertebrate 
animals, its extreme excitability, the intimate 
connection of its columns with one another, so 
that one can scarcely be irritated without the 
others being affected, the proximity of the 
roots of its nerves to each other, and the diffi- 
culty, nay the impossibility, of stimulating any 
portion of the cord itself without affecting 
either the anterior or the posterior roots, are 
great impediments to accurate experiments, and 
sufficiently explain the discrepancies which are 
apparent in the recorded results of experi- 
ments undertaken by various observers. More- 
over, the resultant phenomena, after experi- 
ments of this kind, are extremely difficult of 
interpretation, especially with reference to sen- 
sation. “ The gradations of sensibility,” re- 
marks Dr. Nasse, “ are almost imperceptible ; 
7210 
the shades are so delicately and so intimately 
blended, that every attempt to détermine the 
line of transition proves inadequate. There is 
a great deal of truth in an expression of Calmeil, 
that it is much easier to appreciate a hemi-pa- 
ralysis of motion than a hemi-paralysis of sen- 
sation. If the anterior fasciculi of the cord 
possess sensibility but only ina slight degree, 
the mere opening of the spinal canal and laying 
bare the cord must cause such a degree of pain 
as would weaken or destroy the manifestations 
of sensibility in the anterior fasciculi. This 
has not been sufficiently attended to by expe- 
simenters. Again, the practice of first irritating 
the posterior fasciculi, and afterwards the ante- 
rior, must have had considerable effect in pro- 
ducing the same alteration. It is plain, that in 
this way the relation which the anterior fasci- 
culi bear to sensation must be greatly obscured ; 
yet, with the exception of some few experiments, 
this has been the order of proceeding generally 
adopted.”* 
All the experimenters agree in attributing to 
the antero-lateral columns more or less power 
of motion, but we gain no satisfactory infor- 
mation from this source respecting their sensi- 
tive power, and probably for the reasons so 
well expressed by Nasse in the passage above 
quoted. But, indeed, we do not need the 
appeal to experiment in reference to this ques- 
tion, although, if a distinct and unequivocal 
response could be elicited by means of it, the 
additional evidence would be of great value. 
There is great difficulty in determining pre- 
cisely the functions of the posterior columns of 
the cord. 
Both anatomy and comparative anatomy are 
opposed to the view which assigns them sensi- 
tive power. In the first place, as already 
stated, there is no evidence to show that the 
posterior roots of the spinal nerves are con- 
nected with them ; even Sir C. Bell, who once 
held that these columns were sensitive because 
the sensitive roots were connected with them, 
gave up that view, having satisfied himself 
that no such connection existed.t Secondly, if 
they were sensitive, it is not unreasonable to 
~expect that they would exhibit an obvious en- 
largement at the situations which correspond to 
the origins of the largest sensitive nerves; so 
little, however, is this the case, that the pos- 
terior columns exhibit little or no variation of 
size throughout their entire course. Thirdly, 
the researches of the morbid anatomist afford 
evidence unfavourable to the assignment of the 
sensitive function to these columns. Cases are 
on record which show that disease of the pos- 
terior columns does not necessarily destroy 
sensibility ; that perfect and even acute sensi- 
bility is compatible with total destruction of 
the posterior columns in some particular region, 
the posterior roots remaining intact: and others 
* Nasse, Untersuchungen zur Physiologie und 
Pathologie, Bonn, 1835-36. The passage is quoted 
from an abstract of the work published in the Brit. 
and For. Med. Review, vol. iv. 
+ See his paper on the relations between the 
nerves of motion and of sensation and the brain, 
The Nervous System, p. 234. 8voed., 1844, 
