49. THE CEREBRAL
HEMISPHERES
Both the cerebral hemispheres constitute the largest part of the brain.
Separated by interhemispheric fissure, interconnected by the corpus
callosum, and merged with the diencephalon to establish continuity with the
brainstem and the spinal cord.
They encase the lateral and third ventricles.
50. The cerebral hemispheres have
🢝
3 surfaces: lateral, medial, and basal;
🢝
3 margins: superior, inferior, and medial;
🢝
3 poles: frontal, temporal
51. THE LOBES OF CEREBRAL HEMISPEHRE
The cerebral hemispheres consists of five lobe :-
Frontal lobe.
Parietal lobe.
Temporal lobe.
Occipital lobe.
Insula.
53. SULCI & GYRI..
Gyrus :- A gyrus (pl. gyri) is a ridge on the cerebral cortex. It is generally
surrounded by one or more sulci.
Sulci :- Depression on the surface of brain.
The course and pattern of the sulci and gyri varies not
only from person to person, but also between the
hemispheres of the same brain
54. Ono et al. have classified the cerebral sulci into three groups
• based on their degree of continuity:
•The first group are those that are commonly continuous or
uninterrupted;
•The second group are those that have low interruption rates; and The
third group are those that are regularly interrupted.
55. ▶
broken in several segments by gyral bridges crossing the sulcus, were the
sylvian fissure ,the callosal and parieto-occipital sulci.
▶Another group that has a high, but not 100%, rate of continuity are the
central, collateral, and calcarine sulci.
▶ Those sulci that are less commonly but still regularly interrupted are the
postcentral, superior, and inferior frontal, superior temporal, cingulate,
occipitotemporal, and the intraparietal sulci.
▶ Those which are usually interrupted by gyral bridges that break up their
continuity are the precentral and inferior temporal sulci
56. PLAN
IDENTIFY THE SYLVIAN FISSURE FIRST,
IDENTIFY THE RAMI OF THE SYLVIAN FISSURE
IDENTIFY THE CENTRAL SULCUS NEXT.
Identify the lobes.
Identify the sulci on each surface
57. SYLVIAN FISSURE
Most distinct and consistent landmark on the lateral surface.
Separating the frontal and parietal lobes above from the temporal
lobe below.
Superficial and a deep part
Superficial part is visible on the
58. SYLVIAN FISSUR
The superficial part has a stem and three
rami; anterior horizontal, anterior
ascending, and the posterior rami
The posterior ramus (the longest),
represents the posterior continuation of
the fissure.
Its posterior end turns more sharply
upward to terminate in the inferior
parietal lobule, where the supramarginal
gyrus wraps around.
The deep part is divided into sphenoidal
and operculoinsular compartments.
59. CENTRAL SULCUS
The central sulcus separates the motor and sensory areas and
the frontal and parietal lobes.
Begins at the superior border of the lateral surface extending
onto the medial surface of the hemisphere in nearly 90% of
cases.
It intersects the upper hemispheric border approximately 2 cm
behind the midpoint between the frontal and occipital poles.
Below, it usually ends about 2.0
60. Directed laterally, inferiorly, and anteriorly,
forming an angle of approximately 70o
Comprises of 2 sinusoidal curves,
the superior curve, has its convexity
directed posteriorly,
and an inferior curve, that is convex
anteriorly,
and together they resemble the shape of an
inverted letter S.
61. IDENTIFICATION OF CENTRAL SULCUS
ON MRI
The central sulcus is easily spotted on the MR scan , with the
help of following signs :-
1. Superior frontal sulcus - pre cs sign
2. Sigmoidal hook sign
3. Pars bracket sign
4. Bifid post-cs sign
5. Thin postcentral gyrus sign
6. Intraparital sulcus - post-cs
7. Midline sulcus sign.
62. THE CENTRAL SULCUS (CS)
Superior frontal sulcus – pre-CS sign
🢝
the posterior end of the superior frontal sulcus joins the
precentral sulcus in 85%
perior
63. Sigmoid “Hook”
– Hook-like configuration of the
posterior surface of the
precentral gyrus
– the “hook” corresponds to the
motor hand area.
– The “hook” is well seen on CT
(89%) and MRI (98%).
The Central Sulcus (CS)
Precentral sulcus
Central sulcus
64. ▶pars bracket sign
▶The paired pars
marginalis form a
“bracket” to each side of
the interhemispheric
fissure at or behind the
central sulcus (96%).
THE CENTRAL SULCUS (CS)
Superior
65. pars bracket sign
The Central Sulcus (CS)
Precentral sulcus
Superior frontalsulcus
Precentral gyrus
Central sulcus
Pars bracket
Pars bracket
66. Bifid post-CS sign
🢝
the post central sulcus is bifid (85%).
🢝
The bifid post-CS encloses the lateral end of the pars marginalis
(88%).
THE CENTRAL SULCUS (CS)
Precentral sulcus
Precentral gyrus
Central sulcus
Postcentral sulcus
Pars bracket
67. Intraparietal Sulcus (IPS) and the post-CS
– in axial MRI, the IPS intersects the post central sulcus (99%).
The Central Sulcus (CS)
Pars bracket
IP
S
Postcentral sulcus
IP
S
Pars bracket
68. NP/MGH
Precentral sulcus
Superior frontal sulcus
Precentral gyrus
Central sulcus
Superior frontalgyrus
Midline Sulcus sign
– the most prominent convexity
sulcus that reaches the midline
interhemispheric fissure is the
CS (70%).
The Central Sulcus (CS)
70. FRONTAL LOBE –ANATOMY
The frontal lobe includes approximately a third of the
hemispheric surface.
It extends from the frontal pole to the central sulcus and is
separated from the temporal lobe by the sylvian fissure.
The frontal lobe presents four surfaces: three formed by a part of
the lateral, medial, and basal cerebral surfaces, and a fourth
sylvian surface .
71. LATERAL SURFACE OF LOBE
3 sulci : The precentral sulci
the superior frontal sulci & the
inferior frontal sulci.
The precentral gyrus parallels
the central sulcus.
Superior and inferior frontal sulci
divide the area into three roughly
horizontal convolutions, the
superior, middle, and inferior
The inferior frontal convolution is divided
72.
73. MEDIAL SURFACE OF THE FRONTAL
LOBE
Formed predominantly by the medial surface of the superior
frontal gyrus, the anterior half of the paracentral lobule, and
the cingulate gyrus.
The frontal lobe is separated from the corpus callosum by the
callosal sulcus and from the parietal lobe by central sulcus.
The paracentral lobule is on the medial surface of the
hemisphere and is the continuation of the precentral and
postcentral gyri.
The cingulate gyrus is the crescent-shaped
74.
75. BASAL (ORBITAL) SURFACE OF
FRONTAL LOBE
Rests on the cribriform plate, orbital
roof, and the lesser wing of the sphenoid
bone.
Inferior surface of the frontal lobe
presents the olfactory sulcus medial to
which lies the gyrus rectus and laterally
lie a number of orbital gyri.
The orbital gyri are divided by the
roughly H-shaped orbital sulcus into the
anterior, medial, posterior, and lateral
orbital groups.
76.
77. PARIETAL LOBE – LATERAL SURFACE
The parietal lobe has three surfaces: lateral,
medial, and a sylvian surface
The lateral surface of the parietal lobe is bounded
anteriorly by the central sulcus, posteriorly by the
upper half of the parietotemporal line, and
inferiorly by the posterior end of the sylvian
fissure and the extended sylvian line.
Two main sulci, the post central and intraparietal
sulci, divide the lateral surface into three parts
78. The post central sulcus divides the parietallobe
into
an anterior convolution, the post central gyrus,
situated behind and parallel to the centralsulcus,
a large posterior part subdivided by the
horizontal sulcus, the intraparietal sulcus, into
superior and inferior parietal lobules.
The intraparietal sulcus is oriented
anteroposteriorly, parallel, and 2 to 3 cm lateral to
the superior border of the hemisphere.
79. The superior parietal lobule
extends from the intraparietal sulcus
to the superior margin of the
hemisphere.
The inferior parietal lobule, the
larger of the two lobules, is divided
into an anterior part formed by the
supramarginal gyrus,
A posterior part formed by the
angular gyrus, which arches over the
upturned end of the superior
temporal sulcus.
80.
81. MEDIAL SURFACE OF
PARIETAL LOBE
The medial parietal surface is situated between the line from the upper end of the
central sulcus to the corpus callosum anteriorly and the parieto-occipital sulcus
posteriorly.
It is formed by the precuneus and paracentral lobule.
The precuneus is a quadrilateral area bounded anteriorly by the ascending ramus
of the cingulate sulcus, posteriorly by the parieto-occipital sulcus, above by the
superior hemispheric border, and inferiorly from the cingulate gyrus by the sub
parietal sulcus.
82.
83. OCCIPITAL LOBE - LATERAL SURFACE
The occipital lobe has three
surfaces: lateral, medial, and basal.
The most consistent sulci, the
lateral occipital sulcus, divides the
lobe into superior and inferior
occipital gyri.
The transverse occipital sulcus
84. MEDIAL SURFACE OF
The medial surface of the
occipital lobe is separated from
the parietal lobe by the
occipital sulcus
The calcarine fissure extends
from the occipital pole toward
the splenium and divides into an
upper cuneus, and a lower
lingula.
The cuneus is a wedge-shaped
lobule, bounded by parieto-
occipital sulcus, calcarine sulcus,
and the superior border of
into the posterior part of the
85. BASAL SURFACE OF THE
OCCIPITAL LOBE
Basal surface of the temporal and occipital lobes are formed by
the same gyri that continue from anterior to posterior across
their uninterrupted border.
They are traversed longitudinally by the longer collateral and
occipitotemporal sulci and the shorter rhinal sulcus that divide
the region from medial to lateral into the parahippocampal and
occipitotemporal gyri and the lower surface of the inferior
temporal gyrus.
The parahippocampal gyrus forms the medial part of the
inferior surface.
86. The collateral sulcus, one of the most constant cerebral
sulci,begins near the occipital pole and extends anteriorly,
parallel,and lateral to the calcarine sulcus.
Posteriorly, it separates the lingula and occipitotemporal gyrus;
anteriorly, it courses between the parahippocampal and the
occipitotemporal gyri.
The rhinal sulcus, is the short sulcus extending along the
lateral edge of the uncus.
The occipitotemporal sulcus courses parallel and lateral to the
collateral sulcus and separates the occipitotemporal gyrus and
basal surface of the inferior temporal gyrus.
The basal surface of the occipital lobe overlying the tentorium
cerebelli is formed by the lower
106. Postcentral sulcus
Superior frontal sulcus
Central sulcus
Intraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Superior parietal gyrus
Centrum semiovale
Parietooccipital sulcus
Precuneus
Angular gyrus
Central sulcus
Inferior frontal gyrus
Supramarginal gyrus
Postcentral sulcus
107. Postcentral sulcus
Central sulcus
Superior frontal sulcus
Pars marginalis
Intraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Angular gyrus
Supramarginal gyrus
Intraparietal sulcus
Superior parietal gyrus
Central sulcus
108. Central sulcus
Postcentral sulcus
Superior frontal sulcus
Precentral sulcus
Intraparietal sulcus
Superior frontal gyrus
Middle frontal
gyrus
Pars marginalis
Superior p arietal
gyrus
Angular gyrus
Postcentral gyrus
Supramarginal gyrus
Precentral gyrus
109. Central sulcus
Postcentral sulcus
Superior frontal sulcus
Precentral sulcus
Pars marginalis
Intraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Precuneus
Paracentral lobule
Superior parietal gyrus
112. NP/MGH
Forceps
minor
Olfactory Sulcus
Lateral orbital gyrus
Inferior Frontal gyrus
Superior Frontal gyrus
Superior Frontal sulcus
Middle Frontal gyrus
Medial Orbital gyrus Gyrus rectus
Anterior Orbital gyrus
Lateral orbital sulcus
113. NP/MGH
Inferior Frontal gyrus
pars opercularis
Superior Frontal gyrus
Middle Frontal gyrus
Sylvian Fissure
Posterior Orbital gyrus
Inferior Temporal gyrus
Cingulate gyrus
Circular insular sulcus
Olfactory Sulcus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Frontal sulcus
short insular gyrus
Gyrus rectus
Medial Orbital gyrus
114. Superior Frontal gyrus
Superior Frontal sulcus
Amygdala
Precentral sulcus
Anterior commissure
Cingulate sulcus
Middle Frontal gyrus
Sylvian Fissure
Superior Temporal gyrus
Superior Temporal Sulcus
Middle Temporal gyrus
Inferior Temporal gyrus
Precentral gyrus
115. Superior Frontal gyrus
Middle Frontal gyrus
Superior Temporal gyrus
Middle Temporal gyrus
Superior Temporal Sulcus
Sylvian Fissure
Heschl’s gyrus
Inferior Temporal sulcus
Inferior Temporal gyrus
Amygdala
Ambient gyrus
Entorhinal area
Cingulate gyrus
Superior Frontal sulcus
Precentral sulcus
Precentral gyrus
116. Superior Frontal gyrus
Middle Frontal gyrus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Fusiform gyrus
Hippocampus
CA1, cornu ammonis
Parahippocampal gyrus
Central Sulcus
120. OPERCULUM OF
temporal lobe
Operculum” means `little lid`.
The cerebral operculum refers to
portions of the frontal, parietal, and
temporal lobes adjacent to the sylvian
fissure and overlying the insula.
It includes the posterior inferior frontal
gyrus, the inferior precentral and
postcentral gyri, the supramarginal
gyrus, the angular gyrus, and the
superior temporal gyrus.
It covers the insula.
121. INSULAR CORTEX
The word “ Insula” means Island. The
insula is the fifth lobe of the brain which
lies folded deep within the sylvian fissure.
The insular cortex is divided into two
parts: the larger anterior insula and the
smaller posterior insula.
The anterior part of the insula is
subdivided by shallow sulci into three or
four short gyri.
The posterior part of the insula is formed
by a long gyrus.
Function - consciousness, cognetive
122. FUNCTIONAL AREAS OF BRAIN
Broca’s area :-
Broca's area is now typically defined in
terms of the pars opercularis and pars
triangularis of the inferior frontal gyrus.
Area 44-45
Linked to speech production.
Wernicke’ area
Involving the posterior section of superior
temporal gyrus.
Brodmann area 22, assocaited with areas
39 &40.
Linked to understanding of written
123. Precentral gyrus (posterior short gyrus) of the anterior lobule
of the insula.
Lesions of Dronker’s area produce
Dronker’s area
124. VENTROLATERAL PREFRONTAL
CORTEX
part of the prefrontal cortex, is
located on the inferior frontal
gyrus, is bounded superiorly by
the inferior frontal sulcus and
inferiorly by the lateral sulcus.
Corresponds to brodmann areas
47,45 & 44.
Function : Inhibition of motor
activity, updating action plans &
decision making.
149. Normal coronal view of the lateral
ventricles and caudao-thalamicgroove.
The level of the trigone of the lateral venticles,
visualizing the body of the choroid plexii.
150. The superior sagittal sinus and other vascular
channels can be readily assessed with power Doppler.
Normal far-posterior coronal.
151. CT brain anatomy
Skull bones and sutures
The brain is located inside the cranial vault, a space formed by bones of the skull and skull
base. Everything inside the cranial vault is 'intra-cranial' and everything outside is 'extra-
cranial'.
Skull bones
Bones of the skull and skull base - frontal, parietal, occipital, ethmoid, sphenoid and
temporal bones - all ossify separately and gradually become united at the skull sutures.
The skull has inner and outer tables of cortical bone with central cancellous bone called
'dipole.
Skull bone structure - CT brain - (bonewindows)
152. Sutures
The main sutures of the skull are the coronal, sagittal,
lambdoid and squamosal sutures. The metopic suture
(or frontal suture) is variably present in adults.
Coronal suture - unites the frontal bone with the
parietal bones
Sagittal suture - unites the 2 parietal bones in the
midline
Lambdoid suture - unites the parietal bones with the
occipital bone
Squamosal suture - unites the squamous portion of
the temporal bone with the parietal bones
Metopic suture - (if present) unites the 2 fontal bones
155. Cranial fossae - CT brain - (bone
windows)
Anterior cranial fossa - accommodates the
anterior part of the frontal lobes
Middle cranial fossae - accommodate the
temporal lobes Posterior cranial fossa -
accommodates the cerebellum and brain
stem
Pituitary fossa (PF) - accommodates the
pituitary gland
156. Meninges
The meninges are thin layers of tissue found
between the brain and the inner table of the skull.
The meninges comprise the dura mater, the
arachnoid, and the pia mater. The dura mater and
arachnoid are an anatomical unit, only separated
by pathological processes.
The falx cerebri and the tentorium cerebelli are
thick infoldings of the meninges which are visible
on CT imaging. Elsewhere the meningeal layers are
not visible on CT as they are closely applied to the
inner table of the skull.
157.
158. Tentorium cerebelli
The tentorium
cerebelli - an infolding
of the dura mater -
forms a tent-likesheet
which separates the
cerebrum (brain) from
the cerebellum
The tentorium is
anchored by the
petrousbones
159. Tentorium cerebelli
On axial slice CT imagesof
the brain the tentorium is
faintly visible passingover
the cerebellum
Tentorium cerebelli - clinical
significance
In the context of
subarachnoid hemorrhage or
subdural hematoma the tent
may become more dense due
to layering of blood.
160. Falx cerebri
The falx is an infolding
of the meninges which
lies in the midline and
separates the left and
right cerebral
hemispheres
Falx cerebri - clinical
significance
Pathological processes
may cause 'masseffect'
with deviation of the
falx towards one side
161. Falx and tentorium
Coronal slice CT images
show that thetentorium
cerebelli is continuous
with the falx cerebri.
Falx and tentorium -
clinical significance
Meningiomas are benign
intracranial tumours
which may arise fromany
part of the meninges,
including the falx or
tentorium.
162. CSF spaces
The brain is surrounded by cerebrospinal fluid (CSF) within
the sulci, fissures and basal cisterns. CSF is also found
centrally within the ventricles. The sulci, fissures, basal
cisterns and ventricles together form the 'CSF spaces', also
known as the 'extra-axial spaces'.
CSF is of lower density than the grey or white matter of
the brain, and therefore appears darker on CT images.
An appreciation of the normal appearances of the CSF
spaces is required to allow assessment of brain volume.
Sulci
The brain surface is formed by folds of the cerebral cortex
known as gyri. Between these gyri there are furrows,
known as sulci, which contain CSF.
163. Sulci and gyri
Gyrus = a fold of the
brain surface (plural
= gyri)
Sulcus = furrow
between the gyri
which contains CSF
(plural = sulci)
164. Fissures.
The fissures are large CSF-filled clefts which separate structures of the brain.
Fissures.
The interhemispheric
fissure separates the
cerebralhemispheres
- the two halves of
the brain
The Sylvian fissures
separate the frontal
and temporallobes.
165. Ventricles
The ventricles are spaces located deep inside the brain which contain CSF.
Lateral ventricles
The pairedlateral
ventricles are located on
either side of the brain
The lateral ventricles
contain the choroidplexus
which producesCSF.
Note : The choroid plexus
is almost always calcified
in adults.
167. Fourth ventricle
The fourth ventricle is located
in the posterior fossa
between the brain stem and
cerebellum
It communicates with the
third ventricle above via a
very narrow canal, the
aqueduct of Sylvius (not
shown).
Basal cisterns
CSF in the basal cisterns
surrounds the brain stem
structures.
168. Brain parenchyma and lobes
The brain consists of grey and white matter structures
which are differentiated on CT by differences in
density. White matter has a high content of
myelinated axons. Grey matter contains relatively few
axons and a higher number of cell bodies. As myelin is
a fatty substance it is of relatively low density
compared to the cellular grey matter. White matter,
therefore, appears blacker than grey matter.
Key points
Grey matter appears grey
White matter appears blacker
169. Grey matter v white matter
White matter is located
centrally and appearsblacker
than grey matter due to its
relatively low density.
Clinical significance
Pathological processes may
increase or decrease the
differentiation in density
between grey and white
matter.
170. Brain lobes
The brain has paired, bilateral anatomical areas or 'lobes'. These do not
exactly correlate with the overlying bones of the same names.
Brain lobes - CT brain
(superior slice)
On both sides the frontal
lobes are separated from
the parietal lobes by the
central sulcus
(arrowheads)
Note: The frontal lobes
are large and the
parietal and occipital
lobes are relatively small
171. Brain lobes - CTbrain
(inferior slice)
The most anterior
parts of the frontal
lobes occupy the
anterior cranialfossae
The temporal lobes
occupy the middle
cranial fossae
The cerebellum and
brain stem occupythe
posterior fossa
172. Lobes v 'regions'
CT does not clearly show the anatomical borders of the lobes of the brain. Forthis
reason radiologists often refer to 'regions', such as the 'parietal region' or
'temporal region', rather thanlobes.
If more than one adjacent region needs to be described then conjoined termscan
be used such as 'temporo-parietal region' or 'parieto-occipitalregion'
Lobes v 'regions'
The parietal lobe is not
clearly delineated from the
temporal or occipital region
173. Grey matter structures
Important grey matter structures visible on CT images of the
brain include the cortex, insula, basal ganglia, and thalamus .
Cortical grey matter
The grey matter of the
cerebral cortex is formed
in folds called gyri
Note that the cortex
appears whiter(denser)
than the underlying
white matter.
174. Ins
T
u
he
la
insula forms an inner
surface of the cerebralcortex
found deep to the Sylvian
fissure.
Insula - clinical significance
Loss of definition of the insular
cortex may be an early sign of
an acute infarct involving the
middle cerebral arteryterritory.
175. Basal ganglia andthalamus
The thalamus and thebasal
ganglia are readily
identifiable with CT
Basal ganglia = lentiform
nucleus + caudatenucleus
Basal ganglia - clinical
significance
Insults to the basalganglia
may result in disorders of
movement.
Thalamus - clinical
significance
Insults to the thalamusmay
result in thalamic pain
syndrome.
176. White matter structures
White matter of the brain lies deep to the corticalgrey
matter.
The internal capsules are white matter tracts which
connect with the corona radiata and white matter of the
cerebral hemispheres superiorly, and with the brain stem
inferiorly.
The corpus callosum is a white matter tract located in the
midline. It arches over the lateral ventricles and connects
white matter of the left and right cerebralhemispheres.
Key points
The internal capsules and corpus callosum are clinically
important white matter tracts.
177.
178. Corpus callosum - CTbrain
- sagittalimage
Sagittal CT images show
the corpus callosum as a
midline structure arching
from anterior to posterior
179.
180. Posterior fossa
The posterior fossa accommodates the cerebellum and brain stem. Superiorly the
cerebellum is separated from the cerebral hemispheres by the tentorium cerebelli.
Posterior fossa
The brain stem and
cerebellum occupy
the posteriorfossa
181.
182. Cerebral vascular territories
Different areas of the brain are supplied by the
anterior, middle and posterior cerebral arteries in a
•predictable distribution. The posterior fossa structures are supplied by the
vertebrobasilar arteries.
•The arteries of the brain are not well visualized on conventional CT, but a
knowledge of the areas of the brain they supply is helpful in determining the
source of a vascular insult.
• Key points
•The cerebral and vertebrobasilar arteries supply regions of the
brain in a predictable distribution.
183. Vascular territories -
(above lateralventricles)
The anterior cerebral
arteries supply a narrow
band of the cerebral
hemispheres adjacent to
the midline .
The middle cerebral
artery supplies the
largest area of the brain.
184. Vascular territories -
(at level of insula)
Multiple tiny
perforating branches
of the middlecerebral
artery supply the
region of the basal
ganglia andinsula
185. Vascular territories –
at level of cerebellum
The vertebrobasilar
arteries supply the
cerebellum and brain
stem
186. Calcified structures
There are several structures in the brain which are
considered normal if calcified. Knowledge of these
structures helps avoid confusion, especially when
considering if there is intracranial hemorrhage present.
The commonly calcified structures include the choroid
plexus, the pineal gland, the basal ganglia, and thefalx.
Key points
Commonly calcified structures of the brain include the
choroid plexus, pineal gland, basal ganglia and falx
Use of CT 'bone windows' is helpful in differentiating
calcified structures from acute hemorrhage.
188. Calcified pinealgland
The pineal gland is
located immediately
posterior to the third
ventricle.
It is very commonlypartly
or fully calcified inadults.
190. Calcified falx cerebri
The falx is commonly
calcified in adults
If viewed on brain
windows only,
calcification of the falx
can be mistaken for acute
intracranialblood
Use of CT 'bonewindows'
show calcification of the
falx more clearly.
192. AXIAL SECTIONS OF CT HEAD
POSTERIOR FOSSACUTS
-ABOVE THE FORAMEN MAGNUM LEVEL
-LEVEL OF THE FOURTH VENTRICLE
-ABOVE THE FOURTH VENTRICULAR LEVEL
-TENTORIAL
SUPRATENTORIAL CUTS
-THIRD VENTRICULAR LEVEL
-LATERAL VENTRICULAR LEVEL
-ABOVE THE VENTRICULAR LEVEL
