THE EXAMINATION OF THE HEAD.
I. METHODS OF EXAMINATION.
1. =Removal of Skull-Cap.= For the section of the head the cadaver
is placed upon its back with its head near the end of the table.
The head may be elevated by a block placed beneath the neck, or it
may be elevated and at the same time firmly held in position by
the use of a special head-rest, different varieties of which are
offered by instrument-makers. It is better to use the simple block
of wood and to control the position of the head with the hands
during the operation. The prosector takes his position behind the
head of the table. The hair of the cadaver is then arranged in such
a manner as to be out of the way, and protected by towels so that
it will not become matted with blood and bone-dust. When the hair
is short it is parted in a line extending from just behind the ears
across the vertex. The shape of the head and the degree of baldness
will determine the exact position of the primary incision through
the scalp; sometimes it must be made farther back than the line
connecting the ears in order that the incision may be concealed.
In the great majority of cases it will be made as follows: The
head is steadied with the operator’s left hand, and turned as far
to the right as possible. The point of the cartilage-knife is then
inserted into the scalp, just within the hair-line, behind the left
ear, and with the belly of the knife the scalp is cut through to the
periosteum, in the line of the hair-part, over the vertex, and as the
head is turned to the left, down to the hair-line behind the right
ear, the knife, as it approaches the end of the incision being raised
so as to make the point finish the cut. This scalp-incision should be
made with a strong and quick drawing movement, but the knife should
not be pressed so firmly against the bone as to cut through the
periosteum, else hemorrhages, collections of pus. etc., may escape
before they are seen.
The scalp is next loosened anteriorly by means of the hands, using
the tip of the cartilage-knife occasionally to nick the fascia and
thus facilitate the working forward of the anterior flap until it
has been loosened as far as the supraorbital ridges anteriorly and
down to the level of the beginning and ending of the incision made
across the vertex. When sufficiently loosened the anterior scalp-flap
is turned over the face, and stretched over the chin, where it will
remain, out of the way, and with both face and hair protected. The
posterior flap of the scalp is then worked back to the same level
at the sides and to the lower border of the occipital protuberance
posteriorly. It is then turned under between the back of the neck and
the wooden block. In stripping the scalp the greatest care should
be taken not to cut or tear off the periosteum. Scars, tumors,
adhesions, traumatic lesions, etc., in the scalp should be carefully
worked out and described as the flaps are loosened. The convex margin
of the fascia of the temporal muscles is now cut with the point of
the cartilage-knife and the muscles are stripped down on both sides
to the level of the folded-over scalp-flaps, where they are either
left hanging down out of the way or are cut off and laid aside. If
they cannot be easily stripped down, they may be scraped off with the
chisel. Some prosectors remove them at the same time with the scalp,
but this is usually not well done. The skull now should be bare,
except for the periosteum, down to the level of a line passing just
above the upper margin of the orbits anteriorly, at the sides just
above the aural opening, and posteriorly just below the occipital
protuberance.
The periosteum is next removed over the entire cranial surface by
means of the chisel, bone-scraper or dull knife. In medicolegal cases
particularly it is of the greatest importance that the periosteum
be removed in this way and the surface of the skull-cap carefully
examined. In ordinary cases the periosteum is often left attached
to the skull-cap when the external examination shows no pathologic
conditions to be present.
After the examination of the periosteum and external surface of the
cranium the skull-cap is removed by sawing in such a way that a space
large enough for the convenient and safe removal of the brain is
afforded. This may be done in several ways. A circular incision may
be made through the skull around its entire circumference just above
the level of the folded-over flaps of scalp. The left hand should
be protected by a folded towel. The head is held firmly in the left
hand and turned slightly toward the left. The saw-cut is then begun
anteriorly about ½ cm. above the supraorbital margins, and continued
around to the right, while the head is turned more and more to the
left. The ear should be held down out of the way by an assistant. The
saw-cut is continued then at the same level to the posterior median
line just below the level of the occipital protuberance. The saw is
then removed and the head turned as far as possible to the right;
the saw-cut is then continued around the left side from the posterior
median line until the beginning of the cut in front is reached and
the circular incision is complete.
[Illustration: FIG. 26.—Author’s method of removing skull-cap.]
Another method of sawing the skull-cap is to saw in two planes,
forming an angle just behind and below the ear (angular method). The
anterior cut is made above the hair-line of the forehead and carried
down at the sides to meet just below and behind the ear the posterior
semicircular cut made at this level. A modification of this method is
to make the anterior and posterior cuts join at a sharper angle in
front of the ears. Both of these methods have for their object the
prevention of disfigurement of the forehead. When the circular method
is used a depression or ridge is often seen in the forehead, after
the restoration of the body, due to the slipping of the skull-cap
after it has been replaced. Such an accident may happen even when the
bones are wired together, unless great care has been taken in wiring.
A more satisfactory way of opening the skull, and one that makes
slipping of the skull-cap after restoration practically impossible,
is the method used by the writer, and illustrated in Fig. 26. The
scalp-incision and the folding back of the flaps are carried out as
described above. The right half of the anterior flap of the scalp
is then taken in the left hand and used to control the position of
the head, the latter being turned to the left as far as possible. An
oblique saw-cut is then made on the right side in a line extending
from the posterior margin of the site of the posterior fontanel, over
the right parietal eminence toward the right mastoid prominence. The
sawing begins on the greatest convexity and is continued upward a
slight distance beyond the median line, and downward far enough to
cross the level of the connecting horizontal cut to be made later at
a level just above the aural canal. The left half of the posterior
scalp-flap is now taken into the left hand and used to steady the
head while it is turned over to the right as far as possible. A
similar oblique cut is then made on the left side, crossing the
one made on the right, in the median line, behind the site of the
posterior fontanel, and extending down across the left parietal
eminence in the direction of the left mastoid prominence. While the
head is still held by the left half of the posterior scalp-flap a
horizontal saw-cut is begun on the left side, just above the aural
canal, intersecting the oblique cut posteriorly and continued around
to the front at a level just above the supraorbital ridges. When the
frontal region is reached the head is steadied by holding the left
half of the anterior portion of the scalp-flap. When the horizontal
cut reaches the right temple the right half of the anterior flap
is taken in the hand, and the head turned to the left while the
cut is carried around the right temporal region to intersect the
right oblique cut. When the skull-cap is removed there is formed
an interlocking joint (Fig. 27) which under ordinary conditions
holds the restored skull-cap firmly without wiring and without the
formation of a ridge or crease on the brow, since the bone cannot
slip. It is best, however, in the event of the shipment of a cadaver
by rail to wire the bones to prevent any forcible dislodgement.
[Illustration: FIG. 27.—Skull-cap after removal, showing posterior
interlocking joint.]
Whatever method is used the greatest care should be taken to saw the
skull-cap without injuring the brain. The difference in thickness
of different portions of the cranium must be borne in mind. Sight,
sound and “the feel” are taken as guides. The outer and inner tables,
the diploë, and the dura have an entirely different resistance and
give a different sound. The saw-dust of the outer table is white,
that of the diploë red, that of the inner table white. As soon as
the saw strikes the dura a peculiar “rustling” or “scraping” sound
is heard, and this should be taken as the warning to stop sawing. On
curved surfaces it is best to begin sawing on the greatest convexity
and to continue until the saw is through and then to extend the cut
from this point. The sawing should be done lightly and quickly,
without too strong pressure. Set the saw carefully at first, to avoid
slipping. The small bone-saw is usually used for this operation; saws
attached to electric or dental engines are sometimes employed. Care
should be taken to bring the beginning and ending of the saw-cut into
the same plane; and the oblique cuts should be symmetrical.
As soon as the sawing is completed, no matter what method is used,
the T-chisel or skull-opener (Fig. 12) is used to spring off the
skull-cap. The chisel-blade is inserted into the saw-cut in the right
frontal region, and turned sideways with a quick, powerful movement
of the right hand. Any portions of the inner table not completely
sawed through (usually in the region of the petrous portion of the
temporal) are thus broken, and the dura is loosened sufficiently from
the inner table to allow the prosector to introduce the fingers of
the right hand beneath the skull-cap in the frontal region and to
hold down the dura while the fingers of the left hand inserted into
the frontal saw-cut pull the skull-cap backward with a powerful tug,
completely separating it from the dura, unless the dura is adherent
throughout, as is the case in very young children, old people, and in
certain pathologic conditions. In the latter case it may be necessary
to cut the dura along the line of the horizontal saw-cut and to
remove it with the skull-cap, cutting the falx as the skull-cap is
lifted. In young children the dura must always be removed with the
skull-cap. In the case of pathologic adhesions an attempt should be
made first to separate them from the lamina vitrea by cutting them
with a knife or chisel-blade inserted through the saw-cut. As the
adhesions are severed the skull-cap is lifted gradually backward.
Too much force should not be used in jerking off the skull-cap, else
the brain may be damaged. Whenever possible the dura should be left
intact, as a better judgment is thereby obtained of the intradural
pressure, and there is less danger of losing the contents of the
subdural space.
Some prosectors use hammer and chisel to remove the skull-cap.
This is a bad method, particularly so in the case of medicolegal
autopsies, as artificial fractures of the skull may thus be produced.
It is safest never to use a hammer in the opening of the skull.
The skull-cap is examined as soon as taken off. If the periosteum
was not previously removed it is now scraped off, and the skull-cap
examined against the light. After its complete examination the
operator proceeds to the removal of the brain.
2. =Removal of the Brain.= The convexity of the dura is first
examined. The narrow-bladed brain-knife or long section knife
(Fig. 3) is now taken in hand, and with the cutting edge directed
upward the point of the blade is inserted into the anterior end
of the superior longitudinal sinus and the sinus cut open as far
posteriorly as the opening in the cranial vault will admit. Its
walls and contents are then examined. With cutting edge outward the
point of the brain-knife is then inserted through the dura just to
the left of the anterior end of the falx and the dura cut around to
the left at the level of the horizontal saw-cut. The knife is then
inserted through the dura just to the right of the falx and the
dura cut in the same way on the right side. The two halves of the
dura are now loosened from the convexity of the brain by breaking
the blood-vessels connecting the dura with the inner meninges. The
index-finger is swept over the convexities and along the sides of
the longitudinal sinus, tearing the pial veins. Pathologic adhesions
should be carefully worked out. The finger is then used to raise
the falx anteriorly so that the point of the brain-knife can be
introduced beneath it to cut it upward and forward. The dura is then
carefully examined and turned back over the brain and allowed to hang
down over the occiput. The inner meninges over the exposed portion of
the brain are now examined; and the brain is then removed as follows:
The four fingers of the left hand are placed beneath the frontal
lobes, lifting these sufficiently for the prosector to be able to cut
the I, II, III, IV and VI cranial nerves, the carotids and pedicle of
the hypophysis down to the tentorium cerebelli. The tentorium is then
cut with the tip of the brain-knife, which is held perpendicularly,
by a gentle up-and-down sawing motion, from left to right along the
superior border of the petrous bones. The V, VII, VIII, IX, X, XI
and XII cranial nerves are then cut as closely as possible to their
exits. As they are cut the brain is lifted gradually more and more,
and supported by the left hand. When all the connections have been
cut except the cord and vertebral arteries these are severed by the
myelotome (Fig. 4), or by the brain-knife, the point of which is put
down through the foramen magnum as far as possible, and the cord and
vertebral arteries severed by a transverse cut made from left to
right as nearly horizontal as possible. The knife is now laid aside
and the first two fingers of the right hand put beneath the two
cerebellar lobes so that the medulla and portions of cervical cord
fall between these fingers, which are then used to lift them upward
and backward. The freed brain is now rolled over backward out of the
cranial cavity upside down onto the palm of the left hand, and is
then placed upon a board, tray or dish ready for examination. If the
cord has already been removed, any portion remaining is taken out
with the brain. In case the cord has been freed and is to be removed
with the brain it is only necessary to cut the vertebral arteries and
then to lift up the brain, drawing the cord up through the foramen
magnum.
3. =Section of the Brain.= (_Modified Virchow Method._) The brain as
it is taken from the cranium is placed upside down, with occipital
lobes toward the prosector. The basal meninges and blood-vessels
are then carefully examined. The hemispheres and convolutions are
separated and the arachnoid torn by the tip of the index-finger or
the handle of a scalpel; and the branches of the cerebral vessels
to their deepest ramifications are thus exposed, giving a complete
picture of the circle of Willis and all of its branches to the point
where they enter the brain-substance. The larger vessels are opened
by transverse or longitudinal cuts and their walls and contents
noted. The brain is then turned over, and the meninges examined over
the entire convexity. The pia and arachnoid are then removed together
over the entire convex and median surfaces of the hemispheres. If
the blood-vessels between the convolutions are seized with the
forceps the meninges can be easily stripped off, the fingers aiding
the forceps, using great care not to tear the brain substance. The
meninges are removed about half-way down the outer sides of the
hemispheres and are there left intact so as to hold the pieces of
brain together after it has been cut, and so permit orientation. The
cortical surface is then examined; if bloody, it should be washed
with a weak stream of water.
[Illustration: FIG. 28.—Method of examination of brain. Opening of
left ventricle. Line showing direction of cuts. (After Nauwerck.)]
The hemispheres are now separated until the corpus callosum comes
into view. The left hemisphere is then held by the left hand, with
the thumb on the median surface and the fingers on the outer and
under sides, so that the hemisphere is turned outward and yet raised
slightly at the same time, thus stretching the corpus callosum over
the cavity of the left lateral ventricle. The point of the narrow
brain-knife (Fig. 3) with cutting edge upward is then introduced
with great care through the corpus callosum about midway between the
genu and splenium and close to the gyrus cinguli (gyr. forn., Fig.
28). The corpus callosum at this point is about 2 to 3 mm. thick and
it is gently nicked with the point of the knife until an opening is
made into the cavity of the ventricle. The knife-point must not be
allowed to slip through to damage the basal ganglia beneath. Into the
small opening thus made the brain-knife, held nearly horizontal,
with cutting edge upward, is introduced and the corpus callosum cut
forward until the anterior horn of the ventricle is reached. The
point of the knife is then passed into the horn and the knife-handle
raised and turned over forward, cutting slightly outward through
the frontal lobe to its apex and disclosing the anterior horn. The
knife is then reversed, held horizontally, with cutting edge upward,
and the corpus callosum cut posteriorly from the beginning of the
first cut, until the posterior horn is reached, when the point of
the knife is inserted into the horn and the knife turned over toward
the operator, cutting backward and somewhat outward through the
occipital lobe to its apex and opening up the posterior horn. (See
Fig. 28.) By this method the lateral ventricle is opened first at the
highest point of its cavity, and the fluid contents collect in the
anterior and posterior horns so that the amount and character can be
easily noted.
[Illustration: FIG. 29.—Section of brain. Ventricles opened.
Lines show direction of large longitudinal incisions through
brain-substance. (After Nauwerck.)]
The left hemisphere is now turned still more to the left, and with
the brain-knife a broad, smooth cut is made through it downward and
outward at an angle of 45°, reaching nearly to the cortical surface,
in a line connecting the cut through the frontal lobe with that
through the occipital and passing along the outer borders of the
corpus striatum. The left hemisphere is thus separated in the form of
a prism-shaped mass having a convex under surface. (See Fig. 29.) The
severed hemisphere falls back by the force of its own weight and the
flat cut-surface of the cerebrum is then bisected by a cut made at
right angles to it, from before backward, and extending nearly to the
cortical surface. (See Fig. 29.) In the case of both of these large
incisions of the hemisphere the severed parts are left connected by
a small portion of cortical tissue and the pia. The knife should be
perfectly dry and clean while making these cuts, and the cut surfaces
should not be touched with the fingers or knife-blade, or wet with
water, until they have been carefully inspected. Other straight
parallel cuts may be made through the brain substance toward the
cortex, the severed portions being left connected by the pia so as to
permit future orientation.
The right lateral ventricle is now opened. The four fingers of the
left hand are placed outside and beneath the right hemisphere with
the thumb on the median surface, gently raising the hemisphere toward
the left, taking care to see that the corpus callosum is not pulled
over to the right of the median line. The knife is held in the right
hand beneath the left one. The right ventricle is then opened in the
same way as the left, beginning in the middle of the corpus callosum
near to the gyrus cinguli, and opening first the anterior horn and
then the posterior. The operation is somewhat more difficult on the
right side than it is on the left, owing to the lack of tension
in the cut corpus callosum, so that greater care must be taken to
avoid injuring the floor of the ventricle. After the opening of the
ventricle the right hemisphere is cut by long parallel incisions made
in the same way as on the left side. (See Fig. 29.)
Some prosectors in opening the right ventricle prefer to turn the
board around so that the frontal lobe points to the operator.
The right hemisphere is then held in the left hand and the right
ventricle opened just as if it were the left ventricle, except
that the posterior horn is opened before the anterior. The method
given above can be just as easily learned, and time is saved by not
turning the board around twice, as is necessary in the latter case.
After the right ventricle has been opened the corpus callosum and
fornix are raised by the thumb and index-finger of the left hand,
putting the septum pellucidum on the stretch. The narrow brain-knife
is then introduced through the interventricular foramen from the
right, its blade flat, with cutting edge directed forward and upward,
and the fornix and the corpus callosum are cut anteriorly, exposing
the cavity of the septum pellucidum. To expose the third ventricle,
the corpus callosum, septum pellucidum and fornix are then lifted up
and laid back from the velum chorioides. The tela chorioidea is then,
with the chorioid plexus of the third ventricle, pulled backward from
over the pineal body and the corpora quadrigemina, care being taken
not to tear away the pineal body. The veins entering the tela from
the great ganglia are cut with the point of the knife. The right
descending posterior pillar or crus of the fornix is then lifted with
the thumb and index-finger of the left hand, the brain-knife on the
flat side with cutting edge to the right is introduced beneath it,
and the crus is cut toward the right. The corpus callosum, fornix and
tela are then turned over to the left (see Fig. 29), fully exposing
the pineal body and the corpora quadrigemina.
The cerebellum and medulla are now supported by the index-finger
of the left hand placed beneath the latter; while the brain-knife
is held nearly horizontally in the right, and a deep sagittal cut
is made into the vermis exactly in the median line so as to make
a small opening into the fourth ventricle. The point of the knife
with cutting edge upward is then introduced into this opening and
the incision through the vermis increased anteriorly and posteriorly
until the two cerebellar hemispheres fall apart and the fourth
ventricle is wholly opened. The point of the knife, with cutting
edge upward may then be introduced into the posterior opening of the
aqueduct and the latter opened to the third ventricle, the pineal
body being removed before the cut through the roof of the aqueduct
is made. In the Virchow method the corpora quadrigemina and the
vermiform portion of the cerebellum are sectioned in the median line
by a cut opening up both aqueduct and the fourth ventricle. Other
prosectors open the aqueduct from the third ventricle toward the
fourth. The left cerebellar hemisphere is now cut through in the line
of the middle branch of the arbor vitæ, exposing the dentate nucleus.
Each half of the hemisphere is again bisected by a cut made at right
angles to the surfaces exposed by the first cut. The right cerebellar
hemisphere is then similarly sectioned.
The section of the brain now shows all of the ventricles and their
relations, as well as the condition of a large part of cerebral
and cerebellar brain-substance. (See Fig. 29.) All cut portions
are connected with each other and it is possible to fix the entire
brain as it now stands and later find no difficulty in topographic
orientation. There still remains, however, the demonstration of the
conditions in the basal ganglia, pons, medulla, etc. These structures
are best shown by transverse cuts made across the entire brain as
it lies after the opening of the ventricles. The hemispheres may be
cut singly, but it is better to cut both of them at the same time,
using a dry blade and drawing the knife from left to right, making
identical cuts on the two sides, that the histologic features may
be compared. The transverse cuts may be made in the same region as
recommended in the method of Pitres (see below), or they may be made
closer together. As the cuts are made the sections are separated from
each other by the knife-blade and the cut surfaces examined. After
the cerebrum has been cut transversely in this way the peduncles,
pons, medulla and cervical cord are elevated on the index-finger of
the left hand and also sectioned transversely and the cut surfaces
examined. If the index-finger be placed beneath the medulla parallel
with its long axis, and medulla and pons raised up the cerebellar
lobes fall to the side out of the way. All transverse cuts are
made from left to right and so deep that only a small portion of
brain-tissue, or the basal meninges hold the parts together for
future orientation. The brain is now completely sectioned, with
all parts preserved and capable of being restored to their normal
relations. The parts may be re-assembled and the entire brain put
into the fixing fluid, when it is desirable to save the entire organ
for microscopic study.
[Illustration: FIG. 30.—Method of Pitres. _1, Sectio præ-frontalis_;
_2, Sectio pediculo-frontalis_; _3, Sectio frontalis_: _4,
Sectio parietalis_; _5, Sectio pediculo-parietalis_: _6, Sectio
occipitalis._]
=Other Methods of Opening Brain.= For the demonstration of large
localized pathologic conditions the brain may be opened by a
very simple method of transverse or sagittal incisions extending
entirely through the organ. The broad-bladed brain-knife should
be used and the blade should be wet. The cuts should be made
symmetrically on the two sides and with due reference to anatomic
landmarks. They may be made either from the convexity or from the
basal side.
The method of =Pitres= (see Fig. 30) is also employed for the same
purpose. After the inspection of the meninges and basal vessels
and opening of lateral ventricles, the brain is divided into three
parts, consisting of the two hemispheres and one part made up
of the cerebellum, pons and medulla. The anterior ends of the
cerebral peduncles are cut transversely in front of the corpora
quadrigemina, and the hemispheres are then separated by a sagittal
median incision through the corpus callosum, septum pellucidum,
commissure of third ventricle, substantia perforata posterior,
tuber cinereum and infundibulum, the optic chiasm and neighboring
optic tract having first been removed. The hemispheres are then cut
as follows: The hemisphere is laid upon its median surface with
the occipital lobe toward the operator. The four fingers of the
left hand are then put into the central fissure and six parallel
transverse cuts (see Fig. 30) are made through the hemisphere with
a dry brain-knife, as follows:
1. _Sectio praefrontalis_, through the frontal lobe about 5 cm. in
front of and parallel to the central fissure, exposing the cortex
and medulla of the three frontal convolutions, gyrus orbitalis, and
the convolutions of the median surface of the frontal lobe.
2. _Sectio pediculo-frontalis_, through the “foot” of the frontal
convolutions, exposing the three frontal convolutions, anterior
end of the island of Reil, gyrus orbitalis, corpus callosum, head
of caudate nucleus, anterior portion of lentiform nucleus and
lenticular striated portion of the internal capsule.
3. _Sectio frontalis_, through the anterior central convolution,
showing the anterior central convolution, island of Reil, the
temporal convolutions, corpus callosum, tail of caudate nucleus,
the optic thalamus, middle portion of lentiform nucleus, the
anterior portion of the lenticular part of the internal capsule,
the external capsule and claustrum.
4. _Sectio parietalis_, through the posterior central convolution,
showing the same, the island of Reil, temporal convolutions, corpus
callosum, tail of caudate nucleus, posterior end of optic thalamus
and lentiform nucleus, posterior end of the lenticular-optic part
of internal capsule, the external capsule and the claustrum.
5. _Sectio pediculo-parietalis_, through the foot of the parietal
convolution, 3 cm. posterior to the fissure of Rolando, showing
superior and inferior parietal lobules, temporal convolutions,
corpus callosum, extreme posterior portion of optic thalamus and
tail of caudate nucleus.
6. _Sectio occipitalis_, about 1 cm. in front of the
parieto-occipital sulcus, showing cortex and medulla of occipital
lobe.
After the third cut the fingers of the left hand are taken out of
the central fissure. The sections of brain as they are cut are left
lying in their order with the posterior face of the cut upward. The
same incisions are then made in the other hemisphere and the two
series of sections compared. The cerebellum, pons and medulla are
then examined as described above.
=Section of Brain in Skull.= When the skull-cap is removed by a
circular saw-cut the brain may be cut through with the saw at the
same time; or, after the skull-cap and dura have been removed, the
upper portion of the hemispheres may be sliced off by a horizontal
cut made at the level of the saw-cut. The portions removed are
examined further by sagittal cuts. The lateral ventricles are then
examined in the skull, and the remaining portion of the brain
either cut transversely _in situ_ or removed and sectioned outside
of the cranium. This method is mentioned to be condemned.
For special neuropathologic studies a number of methods have been
advised, the main purpose of which has been to preserve intact
parts of the brain having definite anatomic relationships so that
lesions may be studied by means of serial sections of the entire
system involved. The methods of =Déjerine= and =Meynert= are
employed for this purpose.
_Method of Déjerine._ After a careful examination of the cortical
surface for the presence of lesions, and of the inferior
surfaces of the crura for secondary degenerations, the pons is
cut horizontally in a plane parallel with the inferior surface
of the hemispheres and passing just above the great root of the
trifacial. The brain is thus divided into two portions, one
consisting of the two peduncles and superior portion of the
pons, the other containing the remaining portion of the pons,
the cerebellum and the medulla. The cut surfaces of the pons are
examined for evidences of degeneration in the pyramidal tracts,
and the hemispheres are separated after it has been determined
in which one the lesion is located. If the lesion is found to
be central the degenerations of importance will be found in the
tracts of the internal capsule and in the region of the tegmentum.
The hemispheres are then opened by horizontal incisions passing
through the superior third of the optic thalamus. If the lesion
is cortical the hemispheres are divided into three segments by
two transverse vertical incisions, one passing just posterior to
the splenium of the corpus callosum, the other just anterior to
the knee. The posterior segment consists of the occipital lobe
and part of the parietal; the central one contains the regions
adjacent to the fissure of Rolando, the middle portion of the
temporal convolutions, the basal ganglia, the cerebral peduncle and
corresponding portion of the pons; the anterior segment consists of
the forepart of the frontal lobe. The segments are then fixed and
hardened and cut on a brain-microtome. The anterior and posterior
segments are sectioned vertically transversely, the central segment
is cut horizontally. By this method cortical lesions may be
accurately located, and the entire course of degenerating fibres
followed out.
_Method of Meynert._ This method aims to separate all portions
of the brain possessing differences of internal structure that
may be taken as indicating difference in significance, and to
compare them by weight. The natural furrows or fissures are used as
incision-lines, and three series of dissections are made, the first
of which, here given, is the separation of the brain into three
parts, the brain-mantle, brain-stem and cerebellum. The brain, with
pia still intact, is placed base upward, with cerebellum toward
operator. The arachnoid covering the fissure of Sylvius is cut
or torn, and the island exposed. The three furrows bounding it
must be plainly seen. The pia between the optic tract and uncus,
as well as that in the middle portion of the transverse fissure
between corpora quadrigemina and corpus callosum, is cut, and the
under surface of the splenium of the corpus callosum is freed from
membranous adhesions to the corpora quadrigemina and the pineal
body. When the medulla with pons and cerebellum is now elevated the
transverse fissure gapes open, and permits a free look into the
lateral ventricles.
The brain-mantle on both sides is now separated from the brain-stem
at the basal portion of its frontal end. The knife, held nearly
horizontal, is introduced into the fissure between the posterior
border of the orbital convolutions and the anterior border of the
lamina perforata anterior; and a cut is made slightly downward, not
quite parallel with the orbital surface, about 3 cm. anteriorly
in the medulla of the orbital convolutions, around the under
surface of the head of the corpus striatum. The temporal ends of
the brain-mantle are then cut through, the knife moving externally
between the temporal lobe and the island, inside between the
descending horn of the lateral ventricle and the optic tract. As
soon as the inner cut has been extended beyond the outer corpus
geniculatum on both sides, the knife is turned downward at right
angles, in a curving stroke, to cut through the junction of the
occipital lobes with the stem, internally along the portion of the
corpus striatum adjacent to the optic thalamus, externally between
the junction of the first temporal convolution with the operculum
on one side, and the posterior end of the island on the other.
When this has been done on both sides the blade of the knife is
turned forward in a semicircular stroke. The posterior end of the
brain-stem is gradually lifted up out of the mantle by elevating
the cerebellum and medulla oblongata. The upper peduncle of the
arch of the brain-mantle along the upper border of the island and
the outer border of the corpus striatum is severed from the stem
as far as the anterior end of the upper border of the island,
which bends downward into the anterior border. The peduncle of
the fornix with the pedicle of the septum and the lamina of the
knee of the corpus callosum are severed close above the anterior
commissure, and the knife following the anterior border of the
island is carried downward from the head of the corpus striatum.
The remaining connections between the frontal lobes and stem are
put on a moderate stretch and the incision is completed by bringing
the knife back into the first cut made from the opposite direction
parallel with the orbital surface over the upper surface of the
stem. The three arms of the cerebellum are then severed and the
brain-stem, consisting of the island of Reil, the basal ganglia,
crura, pons, medulla and cerebellum, is completely freed and lifted
out of the mantle.
A combination of the Meynert and Virchow methods is used by many.
The lateral ventricles are opened and an incision made along
the fornix into the descending horn. The stem-ganglia are then
cut out and brain-mantle and stem separated. The hemispheres
are then cut by frontal sections made from the anterior end as
far as the central convolutions. From the central convolutions
backward horizontal sections are then made; the series of sections
are numbered in order and fixed and hardened for microscopic
examination.
It is evident that the section of the brain can be modified to meet
the individual requirements, according to the nature, location and
extent of the lesion and the character of the study to be made of
the latter. The brain may be fixed and hardened either before or
after sectioning.
[Illustration: FIG. 31.—Base of cranium, after removal of brain.
(After Nauwerck.)]
4. =Examination of Base of Cranium.= After the section of the brain
the prosector returns to the head and examines the basal sinuses
(see Fig. 31) by cutting them open with the point of the brain-knife
or by using small shears and forceps. When cut open the walls of
the sinuses should be laid back for inspection. Ordinarily the
_sinus transversus_, _sinus petrosus superior_, _sinus petrosus
inferior_, _sinus cavernosus_ and the _sinus sigmoideus_ are opened.
The last-named is given especial attention because of the frequency
of thrombosis and its involvement from carious conditions of the
neighboring portions of the temporal bone. In purulent mastoid
inflammation the infection often reaches the meninges by this
route. The _carotids_ and the _exits of the cranial nerves_ (see
Fig. 31) are then examined. The _hypophysis_ (see Fig. 31) is
then removed by making semicircular cuts through the overlying dura
mater around the gland and then lifting it out of the sella. This
is best accomplished by means of the small scalpel and forceps. It
is sometimes necessary to chisel away the overhanging bony parts in
order to remove the hypophysis without damaging it. When removed it
may be sectioned by a sagittal cut made either to the left or right
of the pedicle.
[Illustration: FIG. 32.—Incisions for examination of orbit, ear and
nose. x y marks line of incision for exposing nasal tract according
to method of Harke.]
The basal dura is next removed by means of forceps and knife, chisel
or dura-forceps. The bones are then carefully examined for fractures,
caries, etc. Particularly in cases of middle-ear disease, meningitis,
etc., should the dura be removed from the temporal bone and the
latter carefully examined.
5. =Examination of the Orbit.= When the eye-ball cannot be enucleated
anteriorly the orbit may be opened by removing its roof with small
bone-chisel and hammer according to the lines of incision given
in Fig. 32. The dura is, of course, first removed. The bony plate
covering the orbit is thin and easily splintered, so that the chisel
should be very carefully used. The pieces of bone should be removed
with the forceps. The optic foramen and the superior orbital fissure
may be opened at the same time. After the removal of the roof of
the orbit the orbital fat and muscles are dissected away until the
optic nerve and eye-ball are exposed. The sclera is then seized with
the forceps and the eye-ball pulled back and cut quickly around its
equator with sharp shears or scalpel. The head should be held so that
the eye looks downward, so that when cut the vitreous humor falls
out, leaving the retina well spread out over the posterior half of
the bulb. If the retina is thrown into folds it may be straightened
by blowing into it or filling it with water. After the retina has
been examined it may be washed off from the chorioid, leaving it
attached around the papilla. The pigment-layer remains attached to
the chorioid, and when the latter is examined for the presence of
tubercles it should be removed. When removed for microscopic studies
the eye should be placed at once in a suitable fixing fluid.
[Illustration:
FIG. 33.—Tympanic cavity after removal of tegmen. an, mastoid
antrum; ha, hammer-anvil articulation; s, tendon of musc. tens.
tymp.; t. musc. tens. tymp.; g, genu of facial nerve; a, auditory
nerve; f, facial nerve; n, nerv. petros. superfic. major. (After
Politzer.)
]
6. =Examination of the Ear.= The dura is removed from over the
temporal bone and the _tegmen tympani_ cut off with chisel and hammer
as indicated in Fig. 32, _1_, _2_, _3_, _4_, _5_, thus exposing
the tympanic cavity as shown in Fig. 33. When the tegmen tympani
is very hard and compact the hammer and chisel are used to remove
that portion of the tegmen lying laterally to the eminence formed by
the upper semicircular canals. As the ear-ossicles lie immediately
beneath the roof of the tympanic cavity care should be taken not to
injure them with the chisel, and this can be best accomplished by
beginning to chisel so far posteriorly that the tegmen of the mastoid
antrum is first cut away, and from this opening the cut is extended
carefully until the tegmen tympani is removed. When the tegmen of
the tympanic cavity is very thin and porcelain-like, as is often the
case, it may be most quickly and expediently removed by means of
the pointed bone-forceps. A complete view of the tympanic cavity is
obtained by removing the coverings of the mastoid antrum posteriorly
and the bony canal anteriorly after first drawing out the musc.
tensor tymp. from the canal. The mastoid process may be opened with
the saw or with chisel and hammer. The labyrinth may be exposed by
cutting anteriorly with the chisel held horizontally in such a way
as to spring off the upper half of the bony labyrinth, exposing the
vestibule and cochlea. The superior and posterior semicircular canals
come off, and from their open spaces the membranous semicircular
canals can be lifted out with the forceps and then examined in water.
The external auditory canal may be opened and the outer surface of
the ear-drum examined by carrying the anterior flap of the scalp
downward and forward until the entrance into the bony canal is
reached. The external ear is then cut off close to the bone, using
slight pressure so as to avoid tearing out the lining of the canal
or injuring the tympanum. The anterior bony wall of the canal, and
a part of the lower, are then carefully chiseled away until the
membrane is exposed. Any bony projections on the thicker upper or
lower wall of the canal may be trimmed off to give an unobstructed
view. When pathologic changes are present upon any part of the wall
of the canal the latter should be opened from the other side so as to
expose the condition fully.
For the _removal of the auditory apparatus and its examination
outside of the body_ a number of methods are advised. The temporal
bone may be resected by extending the scalp-incision half-way down
the neck along the anterior edge of the trapezius. The anterior flap
with the external ear is carried forward as far as the middle of
the zygoma and below to the angle of the lower jaw. The posterior
flap is carried backward to the middle of the occipital bone. All
soft parts are cut as closely to the bone as possible. A saw-cut
is now made across the posterior cranial fossa, beginning just
behind the mastoid process and extending to the median line of the
clivus half-way between the anterior border of the foramen magnum
and the sella turcica. The sinus sigmoideus is thus included in
the part to be removed. A second saw-cut is then made across the
middle cranial fossa, in a line nearly parallel with the transverse
diameter of the skull, cutting the middle of the zygomatic arch,
the anterior portion of the squama, the great wing of the sphenoid
and the pterygoid process, to the tuberculum sellæ. The median ends
of the two saw-cuts are then united by a chisel-cut in the median
line of the sella and clivus. All bony connections remaining are
then cut with the chisel. The soft parts are then cut, beginning
with those attached to the mastoid process; the loosened bone is
then raised and pulled anteriorly so that the posterior capsule of
the maxillary joint can be cut and the jaw-bone disarticulated. All
remaining soft parts of neck and nasopharynx are now cut and the
temporal bone with the complete ear-apparatus and neighboring portion
of nasopharynx is removed. When both temporal bones are removed the
saw-cuts should not be carried to the median line, but should stop
at the borders of clivus and sella, and then united on each side by
sagittal chisel-cuts made along these borders, leaving the clivus
and sella as a firm connecting bridge between anterior and posterior
portions of the skull. The resected bone may now be examined by means
of a saw-cut made perpendicularly through the apex of the eminence
of the superior semicircular canals and parallel with the crista of
the petrous bone. The tegmen should be removed before the saw-cut is
made and the covering of the tympanic cavity and the outer wall of
the external auditory canal also removed. The tendon of the tensor
tympani is cut and the anvil-stapes articulation severed so that the
saw-blade passes between the drum, hammer and anvil on one side and
the head of the stapes on the other without damaging or displacing
the ossicles. This can be accomplished by pushing outward the drum
with hammer and anvil so that the saw-blade can pass between the
anvil and the head of the stapes. The bone should be held in a vise
and a fret-saw used. On one side of the cut will be seen the drum,
hammer, anvil and anterior portion of the mastoid cells; on the other
the stapes, wall of the labyrinth and posterior half of the mastoid
cells. The Eustachian tube may be easily worked out from the tympanic
cavity or from the pharyngeal opening.
A sagittal section of the middle ear may be made, giving pictures as
shown in Figs. 34, 35. The temporal bone is resected as above, the
tegmen tympani removed and the bony covering of the Eustachian tube
removed with hammer and chisel until the tube is exposed from its
pharyngeal opening to the isthmus. The temporal bone is then divided
into an outer and an inner half by cutting the roof of the tube with
fine straight scissors from the pharyngeal mouth to the bony portion
and then cutting the membranous floor of the canal likewise. The
bony canal, the floor of the tympanic cavity and the mastoid process
are then cut sagittally with a fine fret-saw, passing between the
lower annular segment of the sulcus tympani and the inner wall of
the tympanic cavity. By altering the direction of the saw-cut the
Eustachian tube may be removed in connection with either outer or
inner portion of the temporal bone.
[Illustration:
FIG. 34.—Sagittal section through left middle ear, outer half.
an, mastoid antrum; n, niche of the hammer-anvil body; op, mouth
of Eustachian tube; te, Eustachian tube; it, isthmus of tube; mt,
tympanum; ww, mastoid cells. (After Politzer.)
]
[Illustration:
FIG. 35.—Sagittal section of left middle ear, inner half. op, mouth
of Eustachian tube; te, Eustachian tube; tp, musc. tensor tymp.;
p, promontory; st, stapes; sp, musc. staped; f, facial nerve; an,
mastoid antrum; ww, mastoid cells; ot, ost. tymp. tubæ; u, lower
wall of tympanic cavity. (After Politzer.)
]
Other methods of examining the ear are shown in Fig. 32. The
tympanic cavity and labyrinth may be removed intact by cutting
with a chisel having a cutting edge 3 cm. broad, in the lines _1_,
_2_, _3_, _4_, _5_, as shown in Fig. 32. The cut _1_ is made with
the chisel held nearly horizontal and parallel with the base of
the skull. Cuts _2_, _3_, _4_ and _5_ are made vertically. Great
care must be taken not to splinter the bone. A small chisel can be
used to connect the ends of the cuts. Soft parts are cut away with
the chisel. An elevator is then introduced into cuts _1_ and _2_
and the part lifted out by cutting the remaining soft parts and
the articulation of the lower jaw. The portion removed contains
the inner section of the external auditory canal, tympanic cavity,
ear-drum, a portion of the mastoid cells, the entire labyrinth,
auditory and facial nerves.
_Politzer’s method_ of removing the auditory apparatus in
connection with the nasopharynx and the Eustachian tubes is
also shown in Fig. 32 by the lines _a_, _b_, _c_, _d_, _e_. Two
drill-holes are made in the floor of the anterior fossa at _a_, 1
cm. to the right and to the left of the crista galli, extending
vertically through the nasal cavity to the under surface of the
hard palate. A fine key-hole saw is then introduced through the
right drill-hole, and the base of the skull is then sawed in
the lines _ab_, _bc_, _cd_ and _de_ as indicated in Fig. 32.
Symmetrical cuts are then made on the left side following the same
lines and the two drill-holes connected by a transverse saw-cut.
Any remaining bony connections are then cut with a wide chisel.
In order to cut the bony bridges in the region of the nasopharynx
it may be necessary anteriorly to use the Hey-saw through the
mouth-cavity as well as from the cranial side. To facilitate the
removal of the loosened portion two parallel saw-cuts are made in
the occipital bone 3 cm. to the left and right of the median line,
extending nearly to the posterior edge of the foramen magnum and
connected below by a slightly rounded cut as shown in Fig. 32. A
long-armed chisel can now be used conveniently through the opening
thus made, for horizontal manipulations upon the base of the
skull, while the loosened portion of the base is lifted with the
bone-forceps or nippers set in the posterior saw-cut _e_ and the
_sella turcica_. As the bone is raised the posterior and lateral
pharyngeal walls are cut with the cartilage-knife, the posterior
wall of the capsule of the maxillary articulation on both sides
severed, the jaw disarticulated, and all muscular and membranous
connections cut, until the preparation is completely freed. The
auditory apparatus and the Eustachian tubes can now be examined by
any one of the methods given above.
7. =Examination of Nose and Neighboring Cavities.= Of all the methods
advised for the examination of the nasal cavities the method of
_Harke_ (Fig. 32) is the easiest and gives the best views of the
nasal tract. After the brain has been removed the scalp incision
is carried downward to the middle of the neck on both sides,
following the anterior edge of the trapezius, as for the removal
of the temporal bone. The anterior flap is then carried forward
as far as the bridge of the nose and the edges of the orbits, and
the flap pulled down over the face. The posterior flap is carried
back as far as the upper cervical vertebræ, removing the muscles
with the scalp. The head of the cadaver is now raised and firmly
held by an assistant or clamped in a head-holder; and with the
large meat-saw the occipital bone is sawed through in the median
line, cutting first the squama and then the clivus. The saw is then
set anteriorly into the frontal bone, to the left or right of the
septum, in order not to injure the septum narium. (Fig. 32.) The
sawing then proceeds through the sella turcica, body of the sphenoid,
ethmoid and frontal bones until the base of the skull is divided
into halves. The cartilage-knife is then introduced through the
foramen magnum and the basal ligaments cut. The right and left sides
of the skull posteriorly are then taken in the two hands and with
a quick, powerful tug forced outward until the nasal bones, hard
palate and alveolar processes break apart. The two halves of the
base of the skull then open like a book, turning on an axis, running
through the inferior maxillary articulation and the occipito-atloid
ligaments. If there is too great resistance in the region of the
foramen magnum, the anterior and posterior arches of the atlas may
be cut with a chisel. The sphenoidal sinus, septum narium, frontal
sinus and the nasal cavity on one side of the septum with the
nasopharynx are thus exposed, and their walls and contents may now be
examined. Material for bacteriologic examination should be secured
before further cutting is done. The septum may then be removed with
forceps and scissors, the nasal cavity on the other side examined,
the nasopharynx inspected, and the antrums opened with small
bone-forceps. After the examination is complete the halves of the
base are brought together and fastened with copper wire anteriorly
and posteriorly, taking care that the anterior wire will not be
visible through the skin of the forehead.
8. =Examination of Face.= When the anterior flap of the scalp is
carried down to the edge of the orbits and half-way across the lower
jaw as advised above for the removal of the temporal bone, the
_parotid_ region may be examined. The _upper_ and _lower maxillary
bones_ are best examined after the removal of the neck-organs. A
transverse incision is made in the skin of the neck low enough to
be concealed by the clothing, and connecting with the longitudinal
scalp-incisions. The facial flap is then dissected upward with
great care as far as the infraorbital edges, exposing the maxillary
bones, from which the soft parts must be so carefully removed that
restoration of the face can be made. For the examination of the
anterior nasal-cavities the upper lip must be separated from the
bones.
II. POINTS TO BE NOTED IN SECTION OF HEAD.
1. =Scalp.= Note wounds, hemorrhages, inflammations, scars,
parasites, neoplasms, number and location of bleeding-points on
section, color of different portions, adhesions to periosteum or
cranial bones, etc. Most common pathologic conditions are wounds,
hemorrhages, wens, lipoma, squamous-celled carcinoma, syphilis,
tuberculosis, favus, pediculi, tricophytia, angioma and round- and
spindle-celled sarcomata. The temporal muscles should be examined
for hemorrhages, œdema, purulent inflammations and trichinæ. The
postmortem hypostasis of the back of the head should not be regarded
as pathologic.
2. =Periosteum.= Subperiosteal hemorrhages, purulent infiltrations,
adhesions, indurations, chronic inflammation with new-formation of
bone, and neoplasms are the most common pathologic conditions.
3. =Skull-Cap.= The measurements (circumference, 49-65 cms.; long.
diam., 18 cms.; trans. diam., 13-15 cms.), form, asymmetry, character
of surface (normally smooth and moist), color of cranial bones,
character of sutures and fontanels (easily traced?), supernumerary
sutures and bones, consistence (softened in craniotabes, purulent
inflammations, syphilis, neoplasm), new-formations of bone,
perforations (syphilis, neoplasms, Pacchionian granulations, purulent
inflammation), elevations, depressions, fractures, areas of erosion
or absorption, thickenings of external surface (crater-like due to
organized cephalhæmatoma, chronic periostitis, neoplasm or gumma),
radiating scars or indurations (syphilis), red, soft, spongy
thickenings (rachitis). The temporal and frontal regions are most
frequently the seat of syphilitic (corona veneris) and rachitic
changes (frontal and temporal bosses, square forehead, etc.) Note
ease or difficulty in sawing, relation of external table, diploë and
inner table, measure thickest and thinnest portions, character and
amount of diploë, weight of skull-cap (heavy in sclerosis, light
in atrophy), dural adhesions, examine by transmitted light (color,
blood-content, presence of pus in diploë may be shown by greenish
or yellow color), smooth or rough inner table, erosions (rough,
more or less reddened), grooves of meningeal vessels, Pacchionian
erosions, hyperostosis, exostosis, osteoma, osteophytes (not uncommon
in pregnant women, also in hydrocephalus, acromegaly), atrophy (old
age, craniotabes, hydrocephalus), sclerosis (syphilis). In marked
cachexias (cancer of stomach) the inner table often shows a high
degree of erosion and atrophy.
4. =Dura.= Collections of pus may be found between skull-cap and
dura in purulent inflammations of scalp or diploë. Rupture of middle
meningeal artery or its branches, with or without fracture of the
skull, gives rise to hemorrhagic extravasations in same location. Old
hemorrhages may be partly organized. In young infants the dura is
adherent to the skull-cap and cannot be separated. In youth and adult
life it is adherent only along the longitudinal sinus and about the
blood-vessels; in old age it becomes more adherent. Extent, location
and strength of adhesions should be noted. The normal dura should
be grayish-red, smooth, symmetrically stretched, so that a small
fold only can be taken up by the fingers in the frontal region, and
just translucent enough to show the outlines of the convolutions
and the pial vessels. An increased tension is caused by exudates,
tumor, abscess, hydrocephalus, hemorrhage, congestion, œdema, etc.
Diminished tension occurs in atrophy of the brain, especially marked
in the frontal region, where the dura may be wrinkled and loose.
Perforations of the dura by Pacchionian bodies are very common along
the longitudinal sinus in late life, and should not be regarded as
pathologic. Small osteomata are not uncommon in the same place and
in the falx; they may be very numerous in acromegaly, late syphilis
and cachectic conditions. Changes in the color of the surface of the
dura may be due to hemorrhage, purulent or syphilitic inflammation,
old thickenings, etc. Thickenings are more easily seen from the
inside surface of the dura; they appear as hard, tendon-like, opaque
areas. The normal inner surface is smooth, grayish and moist-shining.
In pachymeningitis it may be dry, dull, roughened, and covered with
blood, pus or fibrin. The most frequent pathologic condition on the
inside of the dura is the organizing or encapsulated hemorrhage
(pachymeningitis hæmorrhagica chronica, hæmatoma duræ), so common
in chronic alcoholics. Miliary tubercles of the dura are common in
meningeal tuberculosis. A gummatous pachymeningitis is not infrequent
in late syphilis. Pachymeningitis fibrosa is also common in old
syphilitics. Actinomycosis occurs in connection with actinomycotic
encephalitis. The primary tumors of the dura are fibroma, osteoma,
fibro-endothelial tumors (psammoma) and angiosarcoma, etc. Secondary
carcinoma or sarcoma is rare.
5. =Longitudinal Sinus.= Character of walls and contents. Thrombosis,
with purulent or gangrenous inflammation, is the most important
condition. Note mouths of superior cerebral veins.
6. =Meningeal Vessels.= Note grooves, rupture, thrombosis,
hemorrhage, infection, amount of blood, symmetry of distribution,
etc. Traumatic rupture of middle meningeal is the most important
condition.
7. =Basal Vessels.= Anomalies in size and distribution, thickness
and character of vessel-walls (sclerosis, atheroma, aneurism,
calcification). Thrombosis, embolism, aneurism, sclerosis, atheroma,
calcification, obliterative endarteritis due to syphilis, are the
most common conditions. The changes in the middle cerebral arteries
are of especial importance in cases of apoplexy, softening, etc.
8. =Inner Meninges.= The arachnoid, subarachnoid space and pia are
usually considered together. The arachnoid bridges over the sulci,
the pia dipping down following the brain substance. The contents
of the subarachnoideal space are best seen, therefore, between the
convolutions. The inner meninges are gray, delicate and transparent;
the pial veins show plainly, the arteries are empty and lie deeper,
while the more superficial veins are uniformly filled with blood.
Sclerotic arteries run more superficially and are more prominent.
The removal of the skull-cap often gives rise to the presence of
air-bubbles in the pial vessels, and this should not be mistaken
for any pathologic condition. Hypostasis likewise should not be
regarded as a pathologic condition. Normally the membranes are
moist; in increased intracranial pressure (tumors, hydrocephalus,
hemorrhages) they are dry and dull. Inflammation is shown by a loss
of transparency of the membrane and by the presence of exudate in
the subarachnoideal space. Old thickenings are white and opaque. The
amount of fluid in the subarachnoideal space may be so great as to
cause the arachnoid to bulge out over the sulci. Note character of
exudate (purulent, fibrinous, serous or hemorrhagic). In purulent
meningitis greenish-yellow or yellowish-white collections of
thin pus are found in the meshes of the arachnoid; in fibrinous
inflammation the exudate is grayish or milky white. The normal fluid
(cerebrospinal) of the subarachnoideal space is clear and small in
amount. It is increased in œdema and congestion, as well as in serous
inflammations. In inflammatory conditions the membranes are dull and
cloudy and the fluid more or less turbid. Pathologic adhesions may
exist between dura and inner meninges, and between the latter and
the brain-substance. In the latter case the meninges do not strip
easily, but pull off portions of the cortex. Over tumors, gummata,
areas of softening, the meninges may be so adherent that they cannot
be separated from each other. In old syphilitics, alcoholics,
cachexias of old age, etc., the pia may be thickened, white and
opaque (leptomeningitis chronica fibrosa). Aneurisms of the pia
vessels are of great importance in cases of meningeal hemorrhage.
They may be very small (size of pea) and often are found only after
very careful search. Atheroma, infective emboli, etc., are also
causes of meningeal hemorrhage. Meningeal tubercles are very common
and often hard to recognize. They are usually best seen over the
basal meninges. Often they can be demonstrated by stripping off the
meninges and floating the membrane in mercuric chloride or formalin
fixing-fluids. After a few minutes’ fixation the tubercles appear as
minute grayish or opaque points, the membrane often appearing as if
sprinkled with fine sand or powder. The Pacchionian bodies of the
arachnoid must not be mistaken for tubercles. They are grayish in
color, and most abundant along the longitudinal sinus. The meninges
over the two hemispheres should be compared as to transparency,
thickness, blood-content, amount of fluid in arachnoideal space, etc.
The most important pathologic conditions of the inner meninges are
anæmia, hyperæmia, stasis (asphyxia), œdema, hemorrhages (stasis,
anthrax, aneurism, atheroma, infective emboli), serous, purulent
and fibrinous inflammation (pyogenic cocci, bacillus pneumoniæ,
pneumococcus, bac. coli, diplococcus intracellularis), chronic
leptomeningitis (syphilis, alcoholism, toxæmia, etc.), tuberculosis,
syphilis (gummatous meningitis), blastomycosis, actinomycosis and
neoplasms. The last named are not common. Cholesteatoma, hæmangioma,
lymphangioma, endothelioma, fibroma, osteoma and lipoma represent
the benign tumors found here. Primary sarcoma is the most common
tumor, usually angiosarcoma, perithelioma, cylindroma, round-cell-,
spindle-cell- or myxosarcoma. Secondary sarcoma and carcinoma occur.
Animal parasites are cysticercus and echinococcus.
8. =Cerebrum.= Weight of brain as a whole 1,200-1,400 grms. (15-50th
year). Cerebrum averages 1,039 grms. in the female, 1,155 grms. in
the male. A weight of 1,100 grms. may be taken as the minimum normal,
and 1,700 grms. as the maximum for the brain as a whole. The relation
of the brain-weight to that of the body is 2-100. In old age there
is a loss of weight. Sagittal diameter 15-17 cm., transverse 14,
vertical 12.5 cm.
Examine the convexity, comparing hemispheres, noting convolutions
and sulci (size, number, symmetry, etc.) Atrophy of the gyri is
shown by increased width of sulci and the narrower, sharper gyral
apex. With increased intracerebral pressure the gyri are flattened
and broader, and the sulci smaller. Note color and consistence
of cortex, adhesions with pia, areas of fluctuation, induration,
depressions, yellow softening, recent and old hemorrhages, effects
of trauma, tumors, tubercles, gummata, etc. Examine median surfaces,
note arching of corpus callosum. On section of the brain note _color_
(pale in anæmia, red in capillary hyperæmia; hemorrhages, areas of
softening, tumors, tubercles, gummata, sclerotic areas, abscesses,
etc., all show color variation from the normal gray or white);
_consistence_ (soft in degeneration and abscess, hard in sclerosis),
_moisture_ (normally is moist-shining; moisture increased in œdema,
inflammation, abscesses, soft tumors, recent degenerations; dry in
old caseous tubercles and gummata, and in anæmia), _blood-content_
(number of bleeding-points, distinguish from punctate hemorrhages),
_character of cut surface_ (normally smooth, sclerotic areas,
abscesses and areas of softening are uneven and depressed, hard
tumors and sclerotic blood-vessels are elevated above the surface).
The absolute and relative size of cortex and medulla, and the
distinctness of the boundary between them, should be noted.
Hemorrhages may occur in any part of the brain, and may be large
or small. Rupture into a ventricle is always fatal. The large
hemorrhages are due to rupture of a diseased artery; small punctate
hemorrhages throughout cortex are usually embolic (fatty embolism).
Old hemorrhages are brownish in color (pigment). Areas of softening
are usually the result of embolism, thrombosis or sclerosis. They are
usually yellow, yellowish-white or brownish-yellow or red.
9. =Ventricles.= Contain about a teaspoonful of clear fluid. This
may become purulent, cloudy, hemorrhagic, fibrinous. Note size of
ventricles and horns. (Fluid increased and ventricles dilated in
hydrocephalus.) Character of ependyma normally gray-red, delicate;
may be pale or red, indurated, thickened, roughened (chronic
ependymitis), hemorrhagic, etc. Compare floors of lateral ventricles
as to symmetry (corpus striatum large in hemorrhages), color, etc.
Adhesions are found most frequently in posterior horns. A fine
granulation of the ependyma is caused by miliary tubercles. Large
solitary tubercles may be found in the ventricles. Do not mistake
postmortem softening of ependyma for pathologic changes. In the third
ventricle note the presence of any abnormal contents, character of
wall, symmetry of corpora quadrigemina, etc. Look for same changes in
fourth ventricle as in lateral. Lining is gray-white and delicate;
floor should be gray-white, firm, and show anatomic structures. Gray
sclerotic areas are often present in floor. Solitary tubercles,
tumors (glioma, neuroepithelioma, gliosarcoma, sarcoma), dermoids and
cysticercus-cysts may be found here. Examine aqueduct of Sylvius for
abnormal contents.
10. =Chorioid Plexus.= The tela chorioidea is normally delicate and
translucent. Note color (red, pale, cloudy), swelling, purulent
infiltration, condition of blood-vessels, tubercles, etc. Psammoma,
sarcoma, papillary epithelioma, carcinoma, fibroma, angioma,
cholesteatoma, cysticercus and echinococcus may be found in the tela
and plexus. Cysts due to œdema are very common, also aneurismal
dilatations of the vessels. In cases of hydrocephalus the veins of
Galen should be examined for thrombi or compression from without. In
acute hydrocephalus the plexus is deep red; hyperæmic, its vessels
distended with blood.
11. =Pineal Gland.= The most common pathologic findings are:
psammoma, adenoma, teratoma, sarcoma, formation of cysts (hydrops
cysticus glandulæ pinealis), hypertrophy, abscess (purulent
meningitis), metastatic tumors. In all cases of giantism especial
attention should be paid to the pineal gland as well as to the
hypophysis.
12. =Cerebral Ganglia.= Color, consistence, moisture, blood-content,
hemorrhage, degeneration, sclerosis.
13. =Peduncles.= As above.
14. =Cerebellum.= Cerebellar cortex is 2 mm. thick, grayish-red
in color. Note irregularities in thickness, color, consistence,
blood-content, moisture. Compare hemispheres. White substance
should be shining and moist. Abscesses, tubercles (solitary or
conglomerate), gummata and neoplasms are the most common pathologic
conditions.
15. =Pons.= Consistence firm normally. Note blood-content, relation
of white and gray stripes, hemorrhage, degenerations, cysts,
neoplasms, etc.
16. =Medulla.= Color grayish-white, consistence firm. Note
blood-content, hemorrhages, degenerations and cysts (syringomyelia).
17. =Hypophysis.= Cysts are common, also calcareous concretions.
Adenomatous hyperplasia is the most common tumor (acromegaly,
obesity). Carcinoma, sarcoma, lipoma and teratoma are rare. Gumma and
tubercle occasionally occur; even when the gland is wholly destroyed,
acromegaly does not result. Epithelial tumors of the infundibulum may
occur in association with hypoplasia of the genitals. In diseases
of the thyroid the condition of the hypophysis should be especially
considered.
18. =Basal Sinuses.= Note contents (marantic and infective thrombi),
especially in middle-ear disease and meningitis. Distinguish
postmortem clots from thrombi, the former being dark-red, soft and
moist, and are not adherent to the walls. The walls of the sinus
should be gray, delicate, and shining.
19. =Basal Dura.= Note same conditions as in dura covering convexity.
20. =Cranial Nerves.= Examine and trace to exits. Note atrophy,
degenerations, compression, indurations, thickenings, neoplasms
(neuroma), etc.
21. =Base of Skull.= After the removal of the basal dura the bones of
the base should be smooth and gray-yellowish-red in color. Look for
fractures, caries, roughened areas, exostoses, collections of pus,
hemorrhage, neoplasms, etc.
The most important pathologic conditions of the brain are congenital
defects or malformations (hydrocephalus, microcephalus, etc.),
anæmia, hyperæmia, œdema, hemorrhage (traumatic, spontaneous,
capillary, apoplexy), embolism, thrombosis, arteriosclerosis,
aneurism, anæmic infarction, encephalomalacia (white, yellow and
red softening), pigmented scars, atrophy, secondary degeneration,
encephalitis, (non-purulent, purulent, hemorrhagic, syphilitic,
metastatic, chronic), sclerosis (diffuse, disseminated, focal,
hypertrophic), tuberculosis, syphilis, actinomycosis, blastomycosis,
rabies, primary neoplasms (glioma, neuroglioma ganglionare,
angiosarcoma, spindle-cell sarcoma, polymorphous-cell sarcoma,
perithelioma, endothelioma, angioma, myxoma, fibroma, osteoma,
teratoma, lipoma), primary epithelial tumors of ventricles, pineal
gland and hypophysis (adenoma, cholesteatoma, papillary epithelioma,
carcinoma), metastatic tumors (all forms of carcinoma and sarcoma,
malignant chorio-epithelioma), cysts, parasites (cysticercus,
echinococcus) and traumatic lesions (commotio cerebri, contusio
cerebri, hemorrhage, red softening, puncture and shot-wounds,
infected wounds, traumatic abscess). Especial examination of the
brain should be made in all cases of acromegaly, epilepsy, cretinism,
congenital idiocy, degeneracy, criminal tendency, insanity, chorea,
caisson disease, locomotor ataxia, paralysis agitans, syringomyelia,
spastic paralysis, infantile paralysis, hereditary ataxia, rabies,
all forms of paralysis, motor or sensory disturbances and neuritis.
3. POINTS TO BE NOTED IN EXAMINATION OF EYE.
The fat-tissue in the orbits should be yellowish-white; from it the
red muscles and the white nerves should be easily distinguishable. On
section of the eye-ball the vitreous normally is clear and the retina
uniformly grayish-black and smooth. The most common and important
conditions to be looked for are phlegmonous inflammations, purulent
panophthalmitis, orbital hemorrhage, thrombosis of ophthalmic vein
and sinus cavernosus leading to pachy- and leptomeningitis, neoplasms
of orbit, wall of orbit, eye-ball or lachrymal gland (melanosarcoma,
glioma, gliosarcoma, neuroepithelioma, various forms of sarcoma,
angioma, lipoma, adenoma, carcinoma), affections of individual
muscles (myositis, atrophy), atrophy of optic nerve, choked disk,
retinitis, choroiditis, iritis, glaucoma, etc.
4. POINTS TO BE NOTED IN EXAMINATION OF EAR.
Note condition of scalp (hyperæmia, œdema, hemorrhage) about ear,
condition of external canal (dry, moist, character of contents),
condition of periosteum, particularly over the mastoid process
(normally grayish-red), condition of bone after removal of periosteum
(normally smooth). Inflammatory œdema, purulent infiltrations in the
soft parts, collections of pus beneath the periosteum, roughness
of bone beneath elevated periosteum, presence of pus or blood in
external auditory canal, perforations of drum, etc., should be noted.
Normally the drum should be grayish-white and shining. Note contents
of middle ear, Eustachian tube, condition of ossicles, mastoid cells
and bone. Lining of middle ear should be grayish-red and smooth; the
cut edges of bone should be uniformly grayish-red. When infiltrated
with pus they are brown or greenish. The mucous membrane is deep-red
or greenish in purulent inflammation; yellow, creamy pus, often of
very offensive odor, may be found in middle ear, Eustachian tube or
external canal. Note character of perforations; old ones have smooth
and thickened edges. The most important pathologic conditions are:
otitis media purulenta, inflammation of mastoid cells, caries of
mastoid process, sinus-thrombosis (leading to meningitis or pyæmia),
otitis media tuberculosa, granulomatous polypi, cholesteatoma,
sclerosis, congenital anomalies, foreign bodies, parasites, neoplasms
(chiefly of external ear).
5. POINTS TO BE NOTED IN EXAMINATION OF NOSE.
The normal mucosa of the nasal tract is light grayish-red. Note
character of contents of the cavities (mucus, blood, pus, dry
clots or scabs), congestion, hemorrhage, erosions, ulcerations,
diphtheritic membrane, diffuse or localized thickenings of the mucosa
(polypi), adenoids, exostoses, caries, foreign bodies, parasites
(maggots) and neoplasms (sarcoma, fibroma, carcinoma). The most
important conditions are acute and chronic catarrhal inflammations,
ozæna, croupous or diphtheritic inflammations, syphilis, atrophy or
hyperplasia of the mucosa, polypi, and more rarely tuberculosis.
Syphilis causes inflammations and gummatous infiltrations of the
mucosa, gummatous periostitis, foul-smelling necrosis of the bony
portions (ozæna syphilitica). Dense hard fibromata developing from
base of skull may fill up the nasopharynx or erode the cranial base
and press upon the brain. Softer sarcomatous growths may arise
from the hypophysis, or from the lymphoid tissue of the mucosa.
Squamous-celled carcinoma is not infrequently primary in the antrum
and thence invades the nose. Primary malignant tumors of nasal tract
not common. Leprosy, glanders, blastomycosis, and rhinoscleroma are
more rarely seen.