anatomy of brain sulcus and gyrus - dr.sajith md rd

Brain AnatomySulci & Gyri

By Dr.Sajith

• Sulcus : A sulcus is depression or fissure in the surface of the brain. ( valleys )

• Gyrus : A gyrus is a ridge on the cerebral cortex. It is generally surrounded by one or more sulci ( hills )

Typical continous fissure

Interhemispheric fissureSylvian fissure ( lateral sulcus )Parieto-occipital fissure Collateral sulcusCentral sulcusCalcarine Sulcus

Interhemispheric fissure

Deep sulcus upto corpus collosum

Divides brain into two hemisphere

Sylvian fissure

deep, mostly horizontal

insula is buried within it

separates temporal lobe from parietal and frontal lobes

Parieto - occipital fissure

very deepoften Y-shaped

from sagittal view

X-shaped in horizontal and coronal views

Collateral sulcus

Divides lingual and parahippocampal gyri from fusiform gyrus.

Central sulcus

usually freestanding (no intersections)

Seperates frontal and parietal lobe.

Calcarine sulcus

Lobes of brain

Frontal lobe.Parietal lobe.Temporal lobe.Occipital lobe.

Limbic lobe.Insular lobe.

• Frontal lobe:Anterior region of hemisphere; anterior to central sulcus, superior to sylvian fissure• Parietal lobe: Posterior region of hemisphere; posterior to central sulcus, anterior to parietooccipital sulcus• Occipital lobe: Posterior to parietooccipital sulcus• Temporal lobe: Inferior to sylvian fissure, anterior to angular gyrus

Lateral surface of brain

Medial surface of brain

Basal surface of brain

frontal lobe

The frontal lobe constitutes the entire region in front of the central sulcus. Immediately in front of the central sulcus lies the precentral gyrus,

which is the primary motor region of the cerebral cortex. In front of the precentral gyrus, the rest of the

frontal lobe is divided into superior, middle and inferior

frontal gyri.

Frontal lobe

Sulci: Superior frontal sulcus. Inferior frontal sulcus. Precentral sulcus.Gyri: Superior frontal gyrus. Middle frontal gyrus. Inferior frontal gyrus. Precentral gyrus

Frontal lobe gyrusLateral Surface Precentral Gyrus --- primary motor area Superior Frontal Gyrus Middle Frontal Gyrus Inferior Frontal Gyrus Pars Opercularis Pars Triangularis Pars Orbitalis Medial Surface Medial Frontal Gyrus Paracentral Lobule

Basal Surface Rectus Gyrus Orbital Gyrus ( superior,

medial ,lateral ,inferior )

Parietal lobe

Behind the central sulcus, and above the lateral fissure, lies the parietal

lobe. Its most anterior part is the postcentral gyrus, which is the

site of the primary somatosensory cortex. Behind the postcentral gyrus,

on the lateral surface of the hemisphere, the intraparietal sulcus divides the rest of the parietal lobe into superior and

inferior parietal lobules.

Parietal lobe

Sulci: Post-central sulcus. Intraparietal sulcus.Gyri: Post-central gyrus. Superior parietal gyrus. Inferior parietal gyrus.

Parietal lobe gyrus

Lateral Surface

Postcentral Gyrus ---- primary somatic area

Superior Parietal Lobule

Inferior Parietal Lobule ---- Wernicke’s area

Supramarginal Gyrus

Angular Gyrus

Medial Surface

Paracentral Lobule

Precuneus

Temporal lobe

The temporal lobe lies beneath the lateral fissure. On its lateral surface

the temporal lobe is divided into three principal gyri that run roughly

parallel to the lateral fissure: the superior, middle and inferior

temporal gyri. The superior temporal gyrus includes the primary

auditory cortex.

Temporal lobe

Sulci: Superior temporal sulcus (parallel

sulcus). Inferior temporal sulcus.Gyri: Superior temporal gyrus. Middle temporal gyrus. Inferior temporal gyrus.

Temporal lobe gyrus

Lateral Surface Superior Temporal Gyrus Middle Temporal Gyrus Inferior Temporal Gyrus

Basal Surface Occipitotemporal Gyrus Medial Occipitotemporal Gyrus Lateral Occipitotemporal Gyrus

Occipital lobe

The boundary between the parietal lobe and occipital lobe is not coincident with a single sulcus on the lateral surface of the

hemisphere; however, it is clearly marked by the deep parieto-occipital

sulcus on the medial surface. The occipital lobe does not bear any

important landmarks on its lateral surface but on the medial surface, the prominent calcarine sulcus indicates

the location of the primary visual cortex.

Occipital lobe

Sulci:• Superior occipital sulcus (extension of

intraparietal sulcus).• Inferior occipital sulcus (extension of

inferior temporal sulcus).Gyri:• Superior occipital gyrus.• Middle occipital gyrus.• Inferior occipital gyrus

Occipital lobe gyrus

Lateral Surface Lateral Occipital Gyrus Superior Occipital Gyrus Inferior Occipital Gyrus

Medial Surface Cuneus Lingual Gyrus

Basal Surface Lateral occipito-temporal gyrus (fusiform

gyrus). Medial occipito-temporal gyrus (lingual gyrus).

Limbic lobeOn the medial surface of the hemisphere, certain

portions of the frontal, parietal and temporal lobes also constitute components of the limbic

system. Curving around the corpus callosum, and running parallel to it, lies the cingulate gyrus ,

separated from the rest of the hemisphere by the cingulate sulcus. The cingulate gyrus passes posteriorly and inferiorly round the posterior portion of the corpus callosum to

become continuous with the parahippocampal gyrus of the temporal lobe. Deep to the

parahippocampal gyrus, within the temporal lobe lies the hippocampus.

The cingulate gyrus, parahippocampal gyrus and hippocampus are referred to as the limbic lobe.

Limbic lobe gyrusOuter Ring Cingulate Gyrus Isthmus of Cingulate Gyrus Parahippocampal Gyrus Uncus, Uncinate Gyrus

Inner Ring Hippocampal Formation Hippocampus, Ammon's Horn Dentate Gyrus Fasciolar Gyrus Supracallosal Gyrus Subcallosal Area (Parolfactory Area)

Insular lobe

• Lies deep in floor of sylvian fissure, overlapped by frontal, temporal and parietal.

• The insular lobe is thought to be involved in sensory and motor visceral functions as well as taste perception.

Insular lobe

Sulci:Central sulcus.Short insular sulcus.Precentral sulcus.Gyri:Anterior insular lobule.Posterior insular lobule.

Insular lobe

Anterior insular lobule (short insular gyri):

Anterior short insular gyrus. Middle short insular gyrus. Posterior short insular gyrus.Posterior insular lobule (long insular

gyri): Anterior long insular gyrus. Posterior long insular gyrus.

Sulcus and gyrus

Sagittal Axial Coronal

Signs to identify sulcus in mri

• The midline sulcus sign: The longest sulcus running horizontally and entering the interhemispheric fissure is the central sulcus .

• The M sign: The typical upper case M shape of the inferior frontal gyrus is formed by its parts ( orbitalis, triangularis, and opercularis ).

signs• The bifid post cg sign: Toward the

interhemispheric fissure, the postcentral gyrus is medially fissured, enclosing the pars marginalis of the cingulated sulcus with both legs and thereby forming the characteristic bifid post cg sign.

• The thin post cg sign: On the surface,

the precentral gyrus has a thicker anteroposterior diameter compared with the postcentral gyrus, which is thinner.

signs

• The handknob: defined the "handknob " as 1 single -shaped dorsally convex bulge of the precentral gyrus.

• The upper T sign: The intersection of the well-identifiable superior frontal sulcus with the precentral sulcus has the shape of an upper case T. The pre cg can be found immediately posterior to this T shape.

signs

• The L sign: The sfg terminates in the pre cg, which runs laterally from the posterior end of the sfg, therefore together forming an upper case L.

• The lower T sign: The inferior frontal

sulcus posteriorly terminates in the pre sc, also in the shape of an upper case T that is dorsally bordered by the pre cg.

signs

• Inverted omega sign : the central sulcus more likely to have the shape of inverted omega.

• The bracket sign: The bihemispheric symmetric pars marginalis of the cingulate sulcus forms an anteriorly opened bracket.

Sagittal

NP/MGHSubcallosal gyrus

Gyrus rectus

Parietooccipital sulcus

Fastigium, fourth ventricle

Cingulate gyrus

Calcarine sulcus

Marginal ramus of Cingulate sulcus

Superior parietal lobule

Paracentral lobule

Cingulate sulcusSuperior frontal gyrus

Cuneus

Lingual gyrus

NP/MGHGyrus rectus


Cingulate gyrus

Calcarine sulcus

Lingual gyrus



Cingulate sulcus

Caudothallamic groove

Precuneus

Central sulcus

Cuneus

Precentral gyrus

Frontomarginal gyrus

Superior frontal gyrus

NP/MGH


Calcarine sulcus



Central sulcusPrecentral sulcus

Precuneus

Corona radiata


Lingual gyrus Inferior occipital gyrus

NP/MGHInferior temporal gyrus Temporal horn, lateral ventricle

Central sulcus

Posterior orbital gyrus


Medial orbital gyrus

Frontopolar gyrus


Lingual gyrusInferior occipital gyrus

Superior occipital gyrus

Middle occipital gyrus


NP/MGH

Central sulcus

Inferior Temporal gyrus

Middle Temporal gyrus

Superior Temporal gyrus

NP/MGH

Central sulcus

Lingual gyrus

Inferior occipital gyrus

Superior parietal gyrus


Superior occipital gyrus

Inferior Temporal gyrusMiddle Temporal gyrus



Anterior orbital gyrus


Inferior frontal gyrus

NP/MGH


Superior Temporal sulcus


Anterior occipital sulcus

Superior frontal sulcus

Precentral sulcus

Central sulcus

Postcentral sulcus

Angular gyrus

Lateral fissure, posterior segment

Inferior frontal gyrus,pars orbitalis




Inferior frontal gyrus,pars triangularis

NP/MGH




Fusiform gyrus

NP/MGH




Parahippocampal gyrus

Hippocampal gyrus

NP/MGH

Temporo-occipital fissure


Lingual gyrusGyrus descendens




Amygdala Hippocampus

NP/MGH

Gyrus rectus

Olfactory sulcusMedial orbital gyrusSubcallosal gyrus


Temporo-occipital fissure


Lingual gyrus

Amygdala

Hippocampus




Gyrus descendens

NP/MGH

Superior occipital gyrusIntra-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

NP/MGH


Superior temporal gyrus

Intra-occipital sulcus


Central sulcus

Superior occipital gyrusParieto-occipital sulcus

Superior temporal sulcus

Lateral fissure

Inferior parietal gyrus

Postcentral gyrus

Lateral fissure

Middle frontal gyrus


NP/MGHSuperior occipital gyrus

CuneusIntra-occipital sulcus


Central sulcus

Precentral sulcus

Precentral gyrus

Central sulcus

NP/MGH

Postcentral sulcus


Central sulcus

Intraparietal sulcus




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

coronal

NP/MGH

Olfactory bulb

Gyrus rectusMedial 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


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


Cingulate gyrusCircular insular sulcus

Olfactory Sulcus



Inferior Frontal sulcusshort insular gyrus

Gyrus rectus

Medial Orbital gyrus

NP/MGH

Superior Frontal gyrusSuperior Frontal sulcus


Superior Temporal Sulcus

Sylvian Fissure

Amygdala

Precentral sulcus

Anterior commissure

Cingulate sulcus




Precentral gyrus

NP/MGH

Superior Frontal gyrus





Fusiform gyrus

Hippocampus

CA1, cornu ammonisParahippocampal gyrus

Central Sulcus

NP/MGH

Paracentral lobule




Central Sulcus

Postcentral gyrus

Cingulate gyrusIntraparietal sulcus

Fusiform gyrus

Collateral sulcusParahippocampal gyrus

Supramarginal gyrus


NP/MGH



Inferior temporal gyrus

Fusiform gyrus

Central sulcusParacentral lobule

NP/MGH

Fusiform gyrus

Lingual gyrusCalcarine sulcus Cingulate gyrus

Inferior temporal gyrus

Middle temporal gyrus

Supramarginal gyrus


Central sulcus

Paracentral lobule

Postcentral gyrus

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anatomy of brain sulcus and gyrus - dr.sajith md rd

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