6 cerebral cortex1

7/27/2019 6 Cerebral Cortex1

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By: Dr. Khulood Al-Khater

Cerebral cortex


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Internal structure ofthe cerebralhemisphere

Gray matter

Cerebral cortexBasal ganglia

White matter

Internal capsule

& coronaradiata..

Ventricles

lateralventricles


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o es o e cere rahemispheres

Frontal lobeParietal lobe

occipital

lobe

Temporal lobe

Insula


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Cerebral cortex (gray matter)

Consists of nerve cells,nerve fibers, neuroglia andblood vessels

Thickness varies from 1.5to 4.5 mm

~10 billion neurons

Function: awareness and

discrimination of differentstimuli


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Cerebral gray matter

It contains 5 types of

neurons

It consists of 6 layers


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Pyramidal cells

Stellate cells

Fusiform cells

Cells of Martinotti

Horizontal cells

Betz cells

(in motor area)


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Layers of the cerebral cortex


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Variation in the cerebral structure

Cerebralcortex

Homotypical

(6 layers)

Heterotypical

(


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I. Frontal Lobe

Primary motor area Secondary motor

area

Supplementarymotor areaLesionUMNparalysis in C/L

limb


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I. Frontal Lobe

LesionUMNparalysis in C/L

limb


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I. Frontal lobe

Frontal eye field Voluntary conjugate

movements of both

eyesLesion: deviation ofthe 2 eyes to the side

of the lesion and

inability to turn the

eyes to the opposite

side

But the involuntary

movement is normal


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I. Frontal lobe

Motor speech area In the dominant

hemisphere (left in

>90% of individuals)

Lesion:

Expressive

Aphasia


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I. Frontal lobe

Prefrontal area Determines the

personality of the

individual

Lesion: abnormal

behavior, loss of

judgment,

emotional changes

(euphoria)


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II. Parietal lobe

Functional areas inthe parietal lobe

Primarysomesthetic area

Secondarysomesthetic area

Somestheticassociation area


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II. Parietal Lobe

Primary somesthetic area

(S1)

In postcentral gyrus &

posterior part of paracentral

lobule Receives afferents from VPL

& VPM thalamic nuclei

Receives sensation from C/L

side of body (few exceptions)Lesion:sensory

disturbance in

the C/L limb


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II. Parietal Lobe

Lesion:sensory

disturbance in

the C/L limb


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II. Parietal Lobe

Secondary somestheticarea (S2)

In the superior lip ofthe posterior ramus ofthe lateral sulcus

Detailed connectionsare unknownfunction?

Lesion: Norecognizable

sensory deficits


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II. Parietal Lobe

Somestheticassociation area

In the superiorparietal lobule

It receives andintegrates differentsensory modalities

(stereognosis)Lesion:Astereognosis


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III. Temporal Lobe

Functional areasin the temporal

lobe

Primary auditoryarea

Secondary

auditory area

Sensory speecharea (Wernickes

area)


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III. Temporal Lobe

Primary auditoryarea (Heschl's

area):

In the inferior wall of the

lateral sulcus

It receives auditory

fibers from the MGBLesion:

Partial deafness inboth ears (unilateral

lesion)

Complete deafness

(bilateral lesion)


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III. Temporal Lobe

Secondaryauditory area

(auditory

association

cortex):

Posterior to the

primary auditory are,

in the inferior wall ofthe lateral sulcus

It receives fibers from

the 1ry auditory area

and thalamus

Lesion:Auditory Agnosia

(word deafness)


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III. Temporal Lobe

Sensory speech

area of Wernicke:

In the dominant

hemisphere (left) : in

the superior temporalgyrus, with extensions

to the parietal region

It permits the

understanding of the

spoken and written

language-the angular

gyrus recogniseswritten lan ua e

Lesion:

Receptive aphasia


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III. Temporal Lobe

Lesion:

Receptive aphasia

Lesion of angulargyrus (in Dominant

hemis):

Alexia & agraphia


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Pathway involved in answering a question:

Ear1ry auditory area2ry auditory area

Wernicke's areaBroca's area1ry motor

area corticobulbar tract muscles involved

in speech (larynx, tongue...)


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Pathway involved inreading a sentence and

repeating it loud:

Retina visual cortex

angular gyrusWernicke's area Broca's

area 1ry motor cortex

corticobulbar tract

muscles involved inspeech (larynx, tongue...)


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Lesion of sensory and

motor speech areas:Global aphasia


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IV. Occipital Lobe

Functional areas inthe occipital lobe

Primary visual

area

Secondaryvisual area

Occipital eyefield


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Primary visual area: Situated in the walls

of the posterior part of

the calcarine sulcus

It receives visualradiation from LGB

Right visual cortexLeft half of the visual field

From Macula

IV. Occipital Lobe

Lesion:Contralateral

homonymous hemianopia

(if both upper & lower

halves are affected)

Lesion:Contralateral quadrantic

hemianopia (if only

upper or lower half)


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Secondary visualarea:

Surrounds the 1ry

visual area

It relates the visualinformation to past

visual experiences

enables the individual

to recognize and

appreciate what he is

seeing

IV. Occipital lobe

Lesion:

Visual Agnosia


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Occipital eye field: In the 2ry visual area

Function: automaticscanning movement

(reflex/involuntary)

IV. Occipital lobe


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Other Cortical Areas

Taste area Vestibular area

Olfactory area

Insula: planning &coordinating the

articulatory movements

necessary for

speech/involved in

visceral sensation

C b l D i


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Cerebral DominanceCertain nervous activity is

predominantly performed by one of

the two cerebral hemispheres

Dominant

(left)

hemisphere

Handedness

LanguageCalculation &

math

Non-dominant

(right) hemisphere

Spacial perception

Recognition of

facesMusic/art

Ambidextrous

individuals

(write withboth hands)


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White Matter of thecerebral hemispheres

Commissuralfibers

Associationfibers

Projectionfibers


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Commissural fibers

Corpus callosum Other commissures:

anterior, posterior,

habenular

commissures andcommissure of the

fornix


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Association fibers

Association

fibers

short long

Uncinatefasciculus

Cingulum

Superiorlongitudinalfasciculus Inferior

longitudinalfasciculus

Fronto-

occipitalfasciculus


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Projection fibers

Internal capsule


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6 cerebral cortex1

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