Sulcal anatomy supratentorial brain, excluding the temporal lobe.

SULCAL ANATOMY OF
EXTRA TEMPORAL
SUPRATENTORIAL
BRAINPresented by – Dr. Sarbesh Tiwari

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.

The cerebral hemispheres have
 3 surfaces: lateral, medial, and basal;
 3 margins: superior, inferior, and medial;
 3 poles: frontal, temporal, and occipital;

THE LOBES OF CEREBRAL HEMISPEHRE
The cerebral hemispheres consists of five lobe :-
 Frontal lobe.
 Parietal lobe.
 Temporal lobe.
 Occipital lobe.
 Insula.

LANDMARKS AND DIVISION
Depicting the four lobes on the lateral surface of the brain

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.
The greatest variability can be seen in the frontal and
parieto-occipital regions.

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.

 According to Rhoton et al, the sulci that were uniformly continuous, not being
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

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 and each lobe.

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 surface of the brain and the deep part
(sylvian cistern) is hidden below the basal surface

SYLVIAN FISSURE
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.

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 to 2.5 cm behind the anterior
ascending ramus of the sylvian fissure without intersecting the
sylvian fissure

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.

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.

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Superior frontal sulcus – pre-CS sign
the posterior end of the superior frontal sulcus joins the
precentral sulcus in 85%
THE CENTRAL SULCUS (CS)
Precentral sulcus
Superior frontal sulcus
Precentral gyrus Central sulcus
Superior frontal gyrus
Precentral sulcus
Precentral gyrus

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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

 pars bracket sign
The paired pars
marginalis form a
“bracket” to each side of
the interhemispheric
fissure at or behind the
central sulcus (96%).
Precentral sulcus
Precentral gyrus
Central sulcus
Pars bracket Paracentral lobule

pars bracket sign
Precentral sulcus
Precentral gyrus
Central sulcus
Pars bracketPars bracket

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Bifid post-CS sign
 the post central sulcus is bifid (85%).
 The bifid post-CS encloses the lateral end of the pars marginalis
(88%).
Precentral sulcus
Precentral gyrus
Central sulcus
Postcentral sulcus
Pars bracket

Intraparietal Sulcus (IPS) and the post-CS
– in axial MRI, the IPS intersects the post central sulcus (99%).
Pars bracket
IPS
Postcentral sulcus
IPS
Pars bracket

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Precentral sulcus
Precentral gyrus
Central sulcus
Midline Sulcus sign
– the most prominent convexity
sulcus that reaches the midline
interhemispheric fissure is the
CS (70%).

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SFS-preCS sign
Hook sign
Pars bracket sign
Bifid post-CS sign
Thin postcentral gyrus
sign
IPS - postCS sign

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 .

LATERAL SURFACE OF FRONTAL
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
frontal gyri.
The inferior frontal convolution is divided into the pars orbitalis, pars
triangularis, and pars opercularis
The pars opercularis and adjacent triangularis are frequently referred to
as Broca’s speech area.

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, or arched,

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.

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

The post central sulcus divides the parietal lobe
into
 an anterior convolution, the post central gyrus,
situated behind and parallel to the central sulcus,
 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.

 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.

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.

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
descends on the lateral surface
behind the posterior part of the
parieto-occipital arcus.

MEDIAL SURFACE OF
OCCIPITAL LOBE The medial surface of the
occipital lobe is separated from
the parietal lobe by the parieto-
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 the
hemisphere.
 The lingula blends anteriorly

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.

 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 part of the lingual gyrus or
lingula.

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NORMAL CORTICAL ANATOMY
Sagittal
Axial
Coronal

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Subcallosal gyrus
Gyrus rectus
Parietooccipital sulcus
Fastigium, fourth ventricle
Cingulate gyrus
Calcarine sulcus
Marginal ramus of
Cingulate sulcus
Precuneus
Paracentral lobule
Cingulate sulcusSuperior frontal gyrus
Cuneus
Lingual gyrus

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Gyrus rectus
Cingulate gyrus
Calcarine sulcus
Lingual gyrus
Marginal ramus of
Cingulate sulcus
Superior parietal lobule
Cingulate sulcus
Caudothallamic groove
Precuneus
Central sulcus
Cuneus
Precentral gyrus
Frontomarginal gyrus

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Calcarine sulcus
Marginal ramus of
Cingulate sulcus
Central sulcus
Precentral sulcus
Precuneus
Corona radiata
Lingual gyrus Inferior occipital gyrus

Inferior temporal gyrus Temporal horn, lateral
ventricle
Central sulcus
Posterior orbital gyrus
Medial orbital gyrus
Frontopolar gyrus
Lingual gyrus Inferior occipital gyrus
Superior occipital gyrus
Middle occipital gyrus

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Central sulcus
Inferior Temporal gyrus
Middle Temporal gyrus
Superior Temporal gyrus

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Central sulcus
Lingual gyrus
Inferior occipital
gyrus
Superior parietal
gyrus
Middle occipital
gyrus
Superior occipital
gyrus
Superior Temporal
gyrus
Anterior orbital gyrus
Inferior frontal gyrus

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Superior Temporal sulcus
Anterior occipital sulcus
Precentral sulcus
Central sulcus
Postcentral sulcus
Angular gyrus
Lateral fissure,
posterior segment
Inferior frontal gyrus,
pars orbitalis
Inferior occipital gyrus
pars triangularis

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Parahippocampal gyrus
Hippocampal gyrus

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Temporo-occipital fissure
Inferior occipital gyrus
Lingual gyrus
Gyrus descendens
Amygdala Hippocampus

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Gyrus rectus
Olfactory sulcusMedial orbital gyrus
Subcallosal gyrus
Lingual gyrus
Amygdala
Hippocampus
Gyrus descendens

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Gyrus rectus
Olfactory sulcus Medial orbital gyrus
Lingual gyrus
Calcarine sulcus
CuneusGyrus descendens
Intra-occipital sulcus

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Cingulate gyrus
Superior occipital gyrusIntra-occipital sulcus

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Cingulate gyrus
Parieto-occipital fissure
Calcarine sulcus
Cuneus
Middle temporal gyrus
Superior temporal sulcus
Superior temporal gyrus
Insula
pars orbitalis
Superior frontal gyrus Middle frontal gyrus
pars opercularis
Lateral fissure
Lateral fissure
Inferior parietal gyrus

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Superior temporal gyrus
Central sulcus
Parieto-occipital sulcus
Superior temporal sulcus
Lateral fissure
Inferior parietal gyrus
Postcentral gyrus
Lateral fissure
Middle frontal gyrus

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Cuneus
Central sulcus
Precentral sulcus
Precentral gyrus
Central sulcus

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Postcentral sulcus
Central sulcus
Intraparietal sulcus
Superior parietal gyrus
Centrum semiovale
Precuneus
Angular gyrus
Central sulcus
Supramarginal gyrus
Postcentral sulcus

NP/MGH
Postcentral sulcus
Central sulcus
Pars marginalis
Angular gyrus
Supramarginal gyrus
Central sulcus

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Central sulcus
Postcentral sulcus
Precentral sulcus
Pars marginalis
Middle frontal
gyrus
Angular gyrus
Postcentral gyrus
Supramarginal gyrus
Precentral gyrus

NP/MGH
Central sulcus
Postcentral sulcus
Precentral sulcus
Pars marginalis
Precuneus
Paracentral lobule

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Olfactory bulb
Gyrus rectus
Medial Orbital gyrus
Inferior Frontal gyrus
Superior Frontal gyrus
Middle Frontal gyrus
Interhemispheric Fissure

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Forceps
minor
Olfactory SulcusLateral orbital gyrus
Superior Frontal sulcus
Medial Orbital gyrus Gyrus rectus
Anterior Orbital gyrus
Lateral orbital sulcus

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pars opercularis
Sylvian Fissure
Posterior Orbital gyrus
Cingulate gyrusCircular insular sulcus
Olfactory Sulcus
Inferior Frontal sulcusshort insular gyrus
Gyrus rectus
Medial Orbital gyrus

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Superior Temporal Sulcus
Sylvian Fissure
Amygdala
Precentral sulcus
Anterior commissure
Cingulate sulcus
Precentral gyrus

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Superior Temporal Sulcus
Sylvian Fissure
Heschl’s gyrus
Inferior Temporal sulcus
Inferior Temporal gyrusAmygdala
Ambient gyrus
Entorhinal area
Cingulate gyrus
Precentral sulcus
Precentral gyrus

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Fusiform gyrus
Hippocampus
CA1, cornu ammonisParahippocampal gyrus
Central Sulcus

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Paracentral lobule
Central Sulcus
Postcentral gyrus
Cingulate gyrusIntraparietal sulcus
Fusiform gyrus
Collateral sulcus
Supramarginal gyrus

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Fusiform gyrus
Lingual gyrus
Calcarine sulcus Cingulate gyrus
Inferior temporal gyrus
Middle temporal gyrus
Supramarginal gyrus
Central sulcus
Paracentral lobule
Postcentral gyrus

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Lingual gyrus
Calcarine sulcus
precuneus
Cingulate gyrus
Tentorium cerebelli
Fusiform gyrus
Inferior parietal lobule
Inferior occipital
gyrus
Lingual gyrus
Collateral sulcus

OPERCULUM OF THE BRAIN
 “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.

INSULAR CORTEX BRAIN
 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
functioning, motor and visceral function.

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 and
spoken language.

Precentral gyrus (posterior short gyrus) of the anterior lobule
of the insula.
Lesions of Dronker’s area produce speech apraxia.
Dronker’s area

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.

Sulcal anatomy supratentorial brain, excluding the temporal lobe.

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Sulcal anatomy supratentorial brain, excluding the temporal lobe.

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