718 
mater and arachnoid immediately near it,— 
tubercular meningitis ; and this may affect more 
or less of the substance of the brain in its 
vicinity, causing red softening. 
Cerebral tubercle is seldom or never alone. 
Other organs of the body are almost invariably 
affected at the same time, the lymphatic or the 
mesenteric glands, or the lungs. It is most 
commonly found in children, and it is not im- 
probable that it may lie dormant for years until 
roused to action by some newly-developed 
morbid excitant. 
Connected with diseased states of the mem- 
branes of the brain, it should be remarked, that 
in many instances acute affections of the mem- 
branes of the brain find their point of departure 
in inflammation of the sinuses. The sinus 
which is most frequently inflamed is the lateral ; 
the inflammatory state of this spreads to the 
neighbouring arachnoid and pia mater, and 
induces all the consequences of a primary me- 
ningitis. 
Mf the abnormal states of the brain.—The 
abnormal conditions of the brain may be con- 
sidered under the heads of —1, congenital ; 
2, acquired or morbid. 
1. Congenital abnormal conditions.—A total 
defect of the brain is found in that state in which 
the head is wanting (Acephalia); and also 
where there is deficiency of the parietal bones 
of the cranium, the occipital, temporal, sphe- 
noid, and frontal being present in an imperfect 
state, and there being also, in general, spina 
bifida of the upper cervical vertebre, there is a 
deficiency of a considerable portion of the en- 
cephalon, the medulla oblongata or a portion 
of it being alone present ( Anencephalia 15 
The acephalic state is very frequent. It is 
always associated with complete or nearly com- 
plete absence of the cranial bones, and frequently 
more or less of those of the spine. In some 
the trunk and extremities are perfect, but in 
very many there are deficiencies to a greater or 
less degree in the formation of these parts. 
In anencephalia there is a defective state of 
encephalon, but not an absence of it; and it 
seems highly probable that this condition is 
due, not so much to an original arrest of deve- 
lopement as to the occurrence of an hydroce- 
— state at an early period of intra-uterine 
ife, the accumulated fluid breaking down the 
newly formed nervous matter, which wants the 
support of the cranial bones. 
e extremest degree of this defect is when 
a large portion of the cranial bones is wanting, 
and also when there is a large fissure in the 
spine. In other cases the spinal fissure does 
not exist. The cranium is largely open on its 
eo and superior aspect, the head thrown 
k, the neck very short and thick, the eye- 
balls very large and prominent, and the mouth 
ially open, giving to the features a very 
ideous expression. 
The hollow of the base of the cranium is, in 
these cases, filled up by a red, soft, highly vas- 
cular substance, continuous with the pia mater 
of the spinal cord. This, in general, appears 
to be nothing more than the cranial pia mater, 
which has collapsed into this state by the de- 
NERVOUS SYSTEM. (Nervous Centres. Annormat Anatomy.) 
struction of the nervous matter, and in which — 
sometimes small masses of nervous matter may 
be discovered here and there. It is eovered by — 
a smooth membrane, which may be an imper- 
fect arachnoid. In some instances, however 
the tumour is of considerable size, more volu- 
minous, according to Geoffroy St. Hilaire, than 
even the normal brain. It is disposed in lobes, 
which resemble somewhat those of the brain, 
and which sometimes contain a considerab 
quantity of serum. 
In less degrees of this condition the crani 
bones are more developed, the skull is les 
open, and the brain and its monbreeene ch: 
a greater degree of perfection. In all 
water is ore the cerebral 
The following case quoted from Penchienati bi 
Breschet in his article Anencephalie, in th 
Dictionnaire de Médecine, illustrates the ap 
pearances in a by no means advanced se © 
the deformity. The subject was a girl which 
had lived three days. striata, 
optic thalami, were present with the hem 
spheres. The lateral and third ventricles wer 
greatly enlarged. The tubercula quadrigemin 
retaining their vesicular condition were likewi 
present, and also the pineal . € 
parts presented at the superior part of the er 
nium a red eminence which was u 
the skin. 
In some cases where the degree of ope 
of = cranium is reduced ye a fissure, in fro 
or behind, a tumour is found protruding thro 
either fissure, consisting of the brain, ir 
fectly developed, inclosed in its membrai 
This condition is frequently combined 
greater or less extent of spina bifida. ’ 
The partial deficiencies of the brain its 
are infinitely various. Those parts which ¢ 
most frequently either altogether absent or 
perfectly developed, are those which are 1 
essential to the production of the organie ¥ 
phenomena. e commissures are very 1 
uently wanting, the smaller ones oftener th 
the larger, such as the corpus callosum and t 
af itaagene The hemispheres of the b 
are uently very imperfectly devel 
The medulla oblongata and mesecepall 
exhibit any material imperfection. ; 
In all cases of idiotcy there is a mat 
imperfection in the developement of the bi 
This is sufficiently plain to the most si 
ficial observer from the small size of the 
which is so frequent a character of this” 
and which is more especially remarkak 
adult life, where the developement of the 
nium by no means keeps pace with that 0 
rest of the body. a 
As an example of the class of changes | 
take place in the brains of most idiots, I sha 
scribe the appearances observed in the br 
an adult idiot which I examined in Oc 
1844. a 
On the upper surface of the brain the con 
lutions were not developed ; the surfac 2 of 
hemispheres was perfectly smooth. ‘The fi 
of Syivius was very deep and well m 
extending upwards and backwards; at its 
terior extremity there was a slight puck 
tac 
i 
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