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.

http://en.wikipedia.org/wiki/Cerebral_cortex

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 supramarginalgyrus 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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HSuperior frontal sulcus – pre-CS signthe 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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H

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 signThe 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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H

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,

convolution on the medial surface between the cingulate sulcus

BASAL (ORBITAL) SURFACE OF FRONTAL LOBERests 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 ramusof 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 into the posterior part of the

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 tentoriumcerebelli 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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Sagittal Neuroanatomy

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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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Cingulate gyrus

Calcarine sulcus

Lingual gyrus


Superior parietal lobule

Cingulate sulcus

Caudothallamic groove

Precuneus

Central sulcus

Cuneus

Precentral gyrus

Frontomarginal gyrus


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Calcarine 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 occipitalgyrus

Superior parietalgyrus

Middle occipitalgyrus






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


Inferior frontal gyrus,pars triangularis

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Axial Neuroanatomy

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Parahippocampal gyrus

Hippocampal gyrus

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Temporo-occipital fissure


Lingual gyrusGyrus 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


Middle occipital gyrusIntra-occipital sulcus

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Cingulate gyrus

Superior occipital gyrusIntra-occipital sulcus


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Intra-occipital sulcus


Cingulate gyrus

Parieto-occipital fissure

Calcarine sulcus

Cuneus

Middle temporal gyrus

Superior temporal sulcus

Superior temporal gyrus

Insula

Inferior frontal gyrus,pars orbitalis

Superior frontal gyrus Middle frontal gyrus

Inferior frontal gyrus,pars opercularis

Lateral fissure

Lateral fissure

Inferior parietal gyrus

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Superior temporal gyrus



Central sulcus

Superior occipital gyrusParieto-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

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Postcentral sulcus

Central sulcus


Pars marginalis





Angular gyrus

Supramarginal gyrus


Central sulcus

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Central sulcus

Postcentral sulcus


Precentral sulcus

Pars marginalis





Angular gyrus

Postcentral gyrus

Supramarginal gyrus

Precentral gyrus

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Central sulcus

Postcentral sulcus


Precentral sulcus

Pars marginalisIntraparietal sulcus



Precuneus

Paracentral lobule


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Coronal Neuroanatomy

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Olfactory bulb

Gyrus rectus

Medial Orbital gyrus

Inferior Frontal gyrusSuperior Frontal gyrus

Middle Frontal gyrus

Interhemispheric Fissure

Inferior Frontal gyrus

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Forceps minor

Olfactory SulcusLateral orbital gyrus

Inferior Frontal gyrus

Superior Frontal gyrus

Superior Frontal sulcus


Medial Orbital gyrus Gyrus rectusAnterior Orbital gyrus

Lateral orbital sulcus

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Inferior Frontal gyruspars 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 Frontal gyrusSuperior Frontal sulcus


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

Superior Frontal sulcus

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



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, cognetivefunctioning, 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.

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Health & Medicine

Sulcal anatomy supratentorial brain, excluding the temporal lobe