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Brief sulcal anatomy of brain .
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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 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.
NP
/MG
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
Superior frontal sulcus
Precentral sulcus
Precentral gyrus
NP
/MG
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%).
THE CENTRAL SULCUS (CS)
Precentral sulcus
Superior frontal sulcus
Precentral gyrus
Central sulcus
Pars bracket Paracentral lobule
pars bracket sign
The Central Sulcus (CS)
Precentral sulcus
Superior frontal sulcus
Precentral gyrus
Central sulcus
Pars bracketPars bracket
NP
/MG
H
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
Intraparietal Sulcus (IPS) and the post-CS
– in axial MRI, the IPS intersects the post central sulcus (99%).
The Central Sulcus (CS)
Pars bracket
IPS
Postcentral sulcus
IPS
Pars bracket
NP
/MG
H
Precentral sulcus
Superior frontal sulcus
Precentral gyrus
Central sulcus
Superior frontal gyrus
Midline Sulcus sign
– the most prominent convexity sulcus that reaches the midline interhemispheric fissure is the CS (70%).
The Central Sulcus (CS)
NP
/MG
H
SFS-preCS sign
Hook sign
Pars bracket sign
Bifid post-CS sign
Thin postcentral gyrus
sign
IPS - postCS sign
The Central Sulcus (CS)
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.
NP/MGH
NORMAL CORTICAL ANATOMY
Sagittal
Axial
Coronal
NP/MGH
Sagittal Neuroanatomy
NP/MGH
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
NP/MGHGyrus rectus
Parietooccipital sulcus
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
Superior frontal gyrus
NP/MGH
Parietooccipital sulcus
Calcarine sulcus
Superior parietal lobule
Marginal ramus of Cingulate sulcus
Central sulcus
Precentral sulcus
Precuneus
Corona radiata
Superior frontal gyrus
Lingual gyrus Inferior occipital gyrus
Inferior temporal gyrus Temporal horn, lateral ventricle
Central sulcus
Posterior orbital gyrus
Frontomarginal gyrus
Medial orbital gyrus
Frontopolar gyrus
Parietooccipital sulcus
Lingual gyrus Inferior occipital gyrus
Superior occipital gyrus
Middle occipital gyrus
Superior parietal lobule
NP/MGH
Central sulcus
Inferior Temporal gyrus
Middle Temporal gyrus
Superior Temporal gyrus
NP/MGH
Central sulcus
Lingual gyrus
Inferior occipitalgyrus
Superior parietalgyrus
Middle occipitalgyrus
Superior occipital gyrus
Inferior Temporal gyrus
Middle Temporal gyrus
Superior Temporal gyrus
Posterior orbital gyrus
Anterior orbital gyrus
Frontomarginal gyrus
Inferior frontal gyrus
NP/MGH
Inferior Temporal gyrus
Superior Temporal sulcus
Superior Temporal gyrus
Anterior occipital sulcus
Superior frontal sulcus
Precentral sulcus
Central sulcus
Postcentral sulcus
Angular gyrus
Lateral fissure, posterior segment
Inferior frontal gyrus,pars orbitalis
Middle Temporal gyrus
Inferior occipital gyrus
Middle occipital gyrus
Inferior frontal gyrus,pars triangularis
NP/MGH
Axial Neuroanatomy
NP/MGH
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Parahippocampal gyrus
Hippocampal gyrus
NP/MGH
Temporo-occipital fissure
Inferior occipital gyrus
Lingual gyrusGyrus descendens
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Amygdala Hippocampus
NP/MGH
Gyrus rectus
Olfactory sulcusMedial orbital gyrus
Subcallosal gyrus
Posterior orbital gyrus
Temporo-occipital fissure
Middle occipital gyrus
Lingual gyrus
Amygdala
Hippocampus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Gyrus descendens
NP/MGH
Superior Temporal gyrus
Middle Temporal gyrus
Gyrus rectus
Olfactory sulcus Medial orbital gyrus
Anterior orbital gyrus
Posterior orbital gyrus
Lingual gyrus
Parahippocampal gyrus
Calcarine sulcus
CuneusGyrus descendens
Temporo-occipital fissure
Middle occipital gyrusIntra-occipital sulcus
NP/MGH
Superior frontal gyrus
Anterior orbital gyrus
Posterior orbital gyrus
Frontomarginal gyrus
Cingulate gyrus
Superior occipital gyrusIntra-occipital sulcus
Middle occipital gyrus
NP/MGH
Superior occipital gyrus
Intra-occipital sulcus
Middle occipital gyrus
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
NP/MGH
Middle occipital gyrus
Superior temporal gyrus
Intra-occipital sulcus
Superior frontal gyrus
Central sulcus
Superior occipital gyrusParieto-occipital sulcus
Superior temporal sulcus
Lateral fissure
Inferior parietal gyrus
Postcentral gyrus
Lateral fissure
Middle frontal gyrus
Inferior frontal gyrus
NP/MGHSuperior occipital gyrus
Cuneus
Intra-occipital sulcus
Middle occipital gyrus
Central sulcus
Precentral sulcus
Precentral gyrus
Central sulcus
NP/MGH
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
NP/MGH
Postcentral sulcus
Central sulcus
Superior frontal sulcus
Pars marginalis
Intraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Superior parietal gyrus
Angular gyrus
Supramarginal gyrus
Intraparietal sulcus
Central sulcus
NP/MGH
Central sulcus
Postcentral sulcus
Superior frontal sulcus
Precentral sulcus
Pars marginalis
Intraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Superior parietal gyrus
Angular gyrus
Postcentral gyrus
Supramarginal gyrus
Precentral gyrus
NP/MGH
Central sulcus
Postcentral sulcus
Superior frontal sulcus
Precentral sulcus
Pars marginalisIntraparietal sulcus
Superior frontal gyrus
Middle frontal gyrus
Precuneus
Paracentral lobule
Superior parietal gyrus
NP/MGH
Coronal Neuroanatomy
NP/MGH
Olfactory bulb
Gyrus rectus
Medial Orbital gyrus
Inferior Frontal gyrusSuperior Frontal gyrus
Middle Frontal gyrus
Interhemispheric Fissure
Inferior Frontal gyrus
NP/MGH
Forceps minor
Olfactory SulcusLateral orbital gyrus
Inferior Frontal gyrus
Superior Frontal gyrus
Superior Frontal sulcus
Middle Frontal gyrus
Medial Orbital gyrus Gyrus rectusAnterior Orbital gyrus
Lateral orbital sulcus
NP/MGH
Inferior Frontal gyruspars opercularis
Superior Frontal gyrus
Middle Frontal gyrus
Sylvian Fissure
Posterior Orbital gyrus
Inferior Temporal gyrus
Cingulate gyrusCircular insular sulcus
Olfactory Sulcus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Frontal sulcusshort insular gyrus
Gyrus rectus
Medial Orbital gyrus
NP/MGH
Superior Frontal gyrusSuperior Frontal sulcus
Middle Frontal gyrus
Superior Temporal Sulcus
Sylvian Fissure
Amygdala
Precentral sulcus
Anterior commissure
Cingulate sulcus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Precentral gyrus
NP/MGH
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 gyrusAmygdala
Ambient gyrus
Entorhinal area
Cingulate gyrus
Superior Frontal sulcus
Precentral sulcus
Precentral gyrus
NP/MGH
Superior Frontal gyrus
Middle Frontal gyrus
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Fusiform gyrus
Hippocampus
CA1, cornu ammonisParahippocampal gyrus
Central Sulcus
NP/MGH
Paracentral lobule
Superior Temporal gyrus
Middle Temporal gyrus
Inferior Temporal gyrus
Central Sulcus
Postcentral gyrus
Cingulate gyrusIntraparietal sulcus
Fusiform gyrus
Collateral sulcus
Parahippocampal gyrus
Supramarginal gyrus
Intraparietal sulcus
NP/MGH
Fusiform gyrus
Lingual gyrus
Calcarine sulcus Cingulate gyrus
Inferior temporal gyrus
Middle temporal gyrus
Supramarginal gyrus
Intraparietal sulcus
Central sulcus
Paracentral lobule
Postcentral gyrus
NP/MGH
Lingual gyrus
Calcarine sulcus
Superior parietal lobule
precuneus
Cingulate gyrus
Tentorium cerebelli
Fusiform gyrus
Inferior parietal lobule
Middle occipital gyrus
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, 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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