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NERVOUS CENTRES. (Human Anatomy. 
emergence of the posterior roots of the spinal 
nerves, indicates the distinction of these two 
sets of fibres. If the posterior column be sepa- 
rated from the antero-lateral in the spinal cord, 
' the separation may be easily carried upwards 
along this line, in a specimen which has been 
sufficiently hardened. 
From the description now given, the res- 
tiform bodies may be regarded as the con- 
necting fibres between the cerebellum and the 
spinal cord. They may be designated the ce- 
rebellar fibres of the medulla oblongata in con- 
tradistinction to the others, which are entirely 
connected with the mesocephale and with the 
cerebrum. 
Rolando describes the restiform body as con- 
taining grey matter—the grey tubercle of Ro- 
Jando. This grey matter, however, may be more 
_ correctly regarded as a portion of the central 
nucleus of the medulla, from which very pro- 
‘gill some fibres of the restiform body emerge. 
he posterior pyramidal columns.—On each 
_ side of the posterior fissure we find a narrow 
column, sufficiently distinct from the restiform 
columns. These may be traced downwards 
through the cervical region of the cord, and 
even into the dorsal or lumbar, according to 
 Foyille. They taper gradually to a fine point, 
the situation of which varies in different sub- 
jects. Superiorly they form the inferior and 
part of the lateral boundary of the fourth ven- 
 tricle. Their innermost fibres end abruptly in 
‘a blunt extremity, whilst the external ones are 
continued upwards on each side of the ven- 
tricle (fig. 386, Y). 
iwary columns.—The oval bodies, which 
form a relief upon the surface of the medulla 
oblongata, have been long known by the names 
corpora olivaria, olive. They occupy the in- 
‘terval between the anterior pyramids and the 
‘restiform bodies, separated, however, from the 
latter by the narrow band of fibrous matter 
above described. 
The surface of each olivary body is crossed 
to a greater or less extent by the arciform fibres, 
‘as already described. Sometimes it is neces- 
sary to remove these fibres, in order to expose 
the proper texture of the olives. 
e superficial layer of each olivary body is 
evidently fibrous, and the constituent fibres seem 
to take a longitudinal course. If a section be 
made so as to remove the prominent convexity 
of this body, it will be seen that the white 
Matter of which it principally consists en- 
closes a layer of vesicular or grey matter dis- 
posed in a peculiar manner. This grey layer 
presents the appearance of a waving line en- 
closing white matter. If the section of the 
olivary body be made transversely, the grey 
waving line is still present, but it presents a 
convex border outwards, and is open within, 
being evidently continuous with the central 
and less definitely disposed grey matter of the 
medulla. And when the section is vertical, 
and so as to divide the olivary body in its entire 
length, the convex border of the grey line is 
still external, but it is open towards the interior 
of the medulla. 
This grey layer, contained within the olivary 
Tue Encepuaton.) €83 
Fig. 387. 
Transverse sections of the medulla oblongata. 
A, anterior. P, posterior. 
o, olivary bodies, in which are seen the undula- 
ting line of grey matter which forms the corpus 
dentatum. 
body, is called the corpus dentatum (corps 
Jestonné, Fr.) It is evidently a capsule of ve- 
sicular matter continuous below with that of 
the cord, internally with that of the central 
substance of the medulla oblongata, and supe- 
riorly with that of the mesocephale (0, fig. 
387). Its disposition, in a convoluted form, 
has doubtless reference to the packing of a 
certain quantity of this matter into a given 
space, and to the important object of bringing 
the vesicular and fibrous matter into connec- 
tion as extensively as possible. 
It has been very commonly supposed that 
the olivary bodies are mere gangliform masses 
laid upon certain ascending fibres of the me- 
dulla, and that they may be readily removed 
without injury to the deeper-seated parts. 
Either of the two following modes of dissec- 
tion will, however, serve to point out the 
erroneousness of this view. If the anterior 
pore be removed, a concave surface is left 
tween the two olivary bodies, in which their 
continuity with the central substance of the 
medulla is distinctly seen. This central sub- 
stance, which forms a substratum on which 
the anterior pyramids rest, and from which it 
is not improbable that some of the fibres of the 
pyramids emerge, is of considerable density. 
Each olivary body appears gradually to merge 
into it; or, adopting another mode of descrip- 
tion, it seems to protrude, forming a relief on 
the exterior, in the interval between the pyra- 
midal and restiform bodies on each side. Ora 
transverse section, as in fig. 387, will exhibit a 
similar continuity between the olivary bodies 
and the central substance of the medulla. 
According to this view, then, the existence 
of the olivary bodies in the human brain and 
_that of the Quadrumana indicates a high de- 
velopement of the central substance of the 
medulla oblongata as compared with its other 
nervous columns. In all the vertebrate ani- 
mals below man, the medulla oblongata in- 
creases with the bulk of the body, and like 
the spinal cord evidently bears a direct relation 
to it. This high developement appears, how- 
ever, to affect more especially the restiform and 
pyramidal bodies, and their connecting fibres, 
the trapezium. The former do not leave any 
