CEREBRAL CORTEX

DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
ESIC MEDICAL COLLEGE, GULBARGA.
DEPT. OF PHYSIOLOGY
CEREBRAL
CORTEX.

OBJECTIVES
 Cerebral cortex
 External features.
 Functional areas.
 Lobes.
 Connections , functions
& applied.
 White matter of
cerebrum.
 Association Fibres.
 Commissural
 Projection.
Monday, March 2, 2015

Cerebral cortex
 External features.
 Cortical functional
areas.
 Phylogenetical division
of cerebral cortex.
 Histological structure.
 Areas , connections,
functions & applied
aspects.

External features.
 Poles.—
 Frontal
 Occipital
 Temporal.
 Surfaces
 Superolateral
 Medial
 Inferior.
 Borders.
 Superomedial
 Inferolateral
 Medial.

CEREBRAL CORTEX
 Sulci & Gyri.
 Surface area of cortex–
2200cm2
 Lobes of cerebral
hemispheres.
 Frontal – Motor.
 Parietal – Sensory.
 Temporal – Auditory.
 Occipital – Vision.

Cortical functional areas.
(Brodmann areas—47)
Motor area
 Primary motor area. (4)
 Premotor area. (6)
 Frontal eye field. (8)
 Supplementary motor
area.
Sensory area
 Primary somaesthetic
areas. (3,1,2)
 Secondary somaesthetic
areas.
 Somaesthetic association
areas. (5,7 & 40)

Auditory area
 Primary auditory area.
(41)
 Auditory association area.
(42).
 Higher auditory
association area. (22)
Visual area.
 Primary visual area. Or
Visuostriate area.(17)
 Visual association area. Or
Peristriate area.(18)
 Visual association area. Or
Perastriate area.(19)

Speech area
 Motor speech.
 Anterior area (44,45)
 Superior area.
 Sensory speech.
 Reading centre.(39)
 Area 40.
 Wernicke’s area. (22)
Smell & Gustatory area.
 Area 28.
 Area 43.

Phylogenetical division of
cerebral cortex.
 Allocortex – 10 % (also called Limbic
Cortex)
 Archipallium – hippocampus & Dentate Gyrus.
 Paleopallium – Uncus & part of Parahippocampal
gyrus.
 Mesocortex. – transitional zone.
 Neocortex. – Isocortex
 Rest of 90% of cerebral cortex.

Histological structure.
 Cells
 Pyramidal cells.
(2/3rd
)
 Stellate cells or
Granule cells. (1/3rd
)
 Fusiform cells.

Histological
structure.
 Laminae.
 Molecular / plexiform layer.
 Transverse nerve fibre –
apical dendrite of
pyramidal cells
 Horizontal cells. – CAJAL
 External granular layer.
 Granule cells &
Pyramidal cells
 Dendrite – to Molecular
layer.
 Axons – to deeper layer.

Laminae.
 Outer pyramidal layer.
 Mainly pyramidal cells,
stellate cells & basket
cells.
 Inner granular layer.
 Densely packed stellate
cells.
 Inner zone prominent
transverse fibres.”
External Band of
Baillarger.

Laminae.
 Inner pyramidal layer.
(Ganglionic)
 Large pyramidal cells.
 Developed in motor
cortex.
 Inner Band of
Baillarger.
 Polymorphous or
multiform layer.
 Modified pyramidal cells.
 Many fusiform cells.

Types of Neocortex.
 Type I or agranular
cortex.
 Granule cells & stellate
cells absent.
 Pyramidal cells – large,
Betz cells.
 Seen in Motor cortex
(4) & Broca’s area. (44)
 Type II or frontal
cortex.
 Triangular granular
cells
 Seen in frontal lobe.

Types of Neocortex.
 Type III or Parietal
cortex.
 Depth & density of layer
II & III increased.
 Granule cells – round.
 Seen in parietal lobe &
junction of parietal,
temporal & occipital
lobe.
 Type IV or Polar Type.
 Cortex narrow
 All layers reduced depth.
 Seen in frontal &
occipital pole.
 Type V or granular
cortex.
 Excess granule cells
 Seen in sensory cortex &
calcarine region.

Areas .
 Frontal lobe
 Parietal lobe
 Temporal lobe
 Occipital lobe.

Frontal lobe.
 Precentral cortex.
 Also called
Excitomotor area of
cortex.
 Stimulation causes
activity in discrete
skeletal muscles
 Sensorimotor cortex.—
sensory & motor
cortex.
 Prefrontal cortex.
 Also called prefrontal
lobe or Orbitofrontal
cortex.
 Ant to area 8 & 44.

Precentral cortex.
Areas.
 Primary motor
area. (area 4) ,
Area 45
 Premotor area.
 Area 6
 Area 8
 Area 44 & 45 or
Broca’s motor
speech area.
 Supplementary
motor area.

Primary Motor Area (4)
 Extent – from
Precentral gyrus to
Paracentral lobule on
medial surface.
 Characteristics –
 6 layers of cortex.
 Giant pyramidal cells
(Betz cells)

Topographic Representation.
 Contra lateral half of
body in inverted order.
 Part of body for skilled
movements – larger
area.
 Body represented
upside down.

Primary Motor Area (4)
 Electrical stimulation.–
Motor homunculus.
 Motor cortex organized
in terms of movements.
 Stimulation of points of
face, pharynx & vocal
cords – bilateral
response.
 Functions – Centre for
volition. i.e. initiation
of movements &
speech.
 Area 45 – suppressor
area.
 Inhibits movements
initiated by area 4.

Sensory Homunculi Motor Homunculi.

Premotor area.
(6,8,44,45)
area 6
 Structurally similar
except Giant
Pyramidal Cells.
 2 parts – Upper 2a,
Lower 2b.
 Topographical
representation – same.
 Functions –
Integration of
voluntary movements.
Make skilled
movements accurate &
smooth.
 Lesions – Hemiplegia
with Spastic paralysis.

Area 8
 Frontal Eye field.
 Location – ant to area 6.
 Function – control eye
movements.
 Lesions – turn eye to
opposite side.
 Conjugate movements --
lost
 Afferent – occipital
lobe & Dorsomedial N.
of Thalamus.
 Efferents – N. of III, IV
& VI Cranial nerves.

Area 44 & 45.
 Broca’s motor
speech area.
 Area 44 – pars
Triangularis.
 Area 45 – pars
Opercularis.
 Functions – in
Dominant
Hemisphere
concerned with
movements
responsible for
production of voice &
articulation of speech.

Supplementary Motor Area.
 Locations – medial
surface of frontal lobe
behind primary motor
area.
 Topographical
representation.–
upper body located
dorsal to lower body.
 Functions – with
Premotor area provide
attitudinal
movements., fixational
movements &
positional movements
of head & eye.

Connections of pre central cortex.
Afferents Efferents.

Prefrontal cortex.
 Major areas. (9-14,
23,24,29,32, 44-47.

Prefrontal cortex.
 Afferents
 Dorsomedial nucleus of
thalamus.
 Anterior nuclei of thalamus.
 Form Papez circuit– close
circuit connection with
thalamus.
 Responsible for resting
EEG & genesis of
Emotions.
 Efferents
 Thalamus. (V &M)
 Tegmental reticular
formation.
 Pontine nuclei
 Caudate nucleus.
 Mammilary bodies.

Functions.
 Centre of planned
actions
 Centre for higher
functions.
 Emotions, learning,
memory & social
behaviour.
 Causes autonomic
changes during emotional
conditions
 Seat of intelligence.
 Register short term
memory
 Called An organ of
mind.
 Control of intellectual
activities.

Control of Intellectual Activities.
 To prognosticate.
 Plan future.
 Concentrate – Central
theme of thought.
 Delay actions in
response to sensory
signals.
 Consequences of
motor action before it.
 Solution of
complicated
mathematical &
philosophical
problems.
 Controls one’s activity
according to moral
laws.

Applied aspects.
Frontal lobe syndrome.
 Cause – ablation of
prefrontal cortex.
 Features. (FEEL –
FILL)
 Flight of ideas.
 Emotional instability.
 Euphoria.
 Loss of moral & social
sense.
 Functional abnormal—
 Hyperphagia.
 Sphincters control loss.
 Disorientation & tremors.
 Impairment of memory.
 Lack of attention &
concentration.
 Lack of initiative & decreased
intellectual activity.

Parietal lobe
 Primary sensory area.
(3,1,& 2)
 Secondary sensory
area.
 Sensory association
areas. (5, 7)

Primary sensory area. (3,1,& 2)
 Location – Post
central Gyrus & Post
wall of Central sulcus.
 Histo – dense stellate
cells , few pyramidal
cells.
 Topographical
representations. –
Sensory Homunculus.
 Lesion – without
thalamus only
discriminative
functions lost
 With thalamus – all
sensation from opp
half of body.

Secondary sensory area.
 Location – post central
Gyrus below 1st
somatic
sensory area.
 Topographical
representation – body
represented twice in
area I & area II.
 Lesion – discriminative
power lost.

Sensory Association Areas. (5, 7)
 Post to area S1.
 Point to point
representation.
 Lesion – Tactile
Agnosia.
(Asteriognosis &
Tactile Aphasia)

Connections of Parietal Lobe
 Afferents.
 SI – Thalamus
(VPM,VPL)
Exteroceptive &
Proprioceptive from opp
side & both sides of face.
 SII – from SI & thalamus
 Sensory Association
area. – SI & SII
 Efferents.
 Corticospinal
 Corticobulbar
 Corticonuclear tracts.

Connections of Parietal Lobe
 Association fibres.
 To other cortical
areas.
 Involve in somatic
sensation.
 Commissural fibres.
 Mostly pyramidal cells
connect to opp
hemisphere.
 Opp area SI & SII

Functions of Parietal Lobe
 First somatic sensory area. (SI)
 Localize, analyze & Discriminate Cutaneous &
Proprioceptive senses.
 Area 3 – touch, pressure, position & vibrations.
 Area 1 – Cutaneous & joint sense.
 Area 2 – deep sense from muscles & joints.

Parietal Lobe
 Second somatic sensory area. (SII)
 From S1 & thalamus directly.
 Perception of sensation.
 Sensory association area. (5,7)
 Discriminate stimuli related to intensity.
 Warm, warmer, cold, colder

Temporal lobe.
Primary auditory area.
 41, 42 Audio sensory Area.
 HEARING CENTRE.
 Middle of superior
temporal gyrus.
 From – MGB, Thalamus.
 To – MGB, Superior
colliculus.
 Perceives – loudness,
pitch, source & direction of
sound.
Auditory association area
 22,21 & 20
 22- Wernicke's area, also
called sensory speech area
in dominant hemisphere.
 Interpretation of meaning,
comprehension of spoken
language & formation of
ideas.
 21,20 – interpretation &
integration of auditory
impulses.

Applied Aspects
 Unilateral removal
of temporal lobe
 Causes no deafness
 As ear bilaterally
represented in
auditory pathway &
project equally to 2
cerebral hemispheres.
 Temporal lobe
syndrome. (Kluver-
Bucy syndrome)
 Bilateral removal of
temporal lobe with
amygdala & Uncus.

Temporal lobe syndrome.
(Kluver-Bucy syndrome)
 Features. (HHH-VADIA)
 Hyperphagia & omniphagia.
 Hyper sexuality.
 Hyper metamorphosis.
 Visual Agnosia.
 Aphasia.
 Dreaming states.
 Increased oral activity.
 Auditory disturbances.

Occipital lobe
 Primary visual cortex.
(17)
 Visual association
area. (18)
 Visual association area
or occipital eye field.
(19)

Connections & functions.
 Afferents.
 LGB via optic radiations.
 Efferents.
 Frontal eye field for eye
movements.
 Superior colliculus.
 Cortico geniculate
projections.
 Thalamus.
 Functions
 Area 17– perception of
visual impulses.
 Area 18, 19 –
interpretation , recognition
& identification from
memory.
 occipital eye field area.–
movement of eye ball.

White matter of cerebrum.
 Association fibres.
 Commissural fibres.
 Projection fibres.

Association fibres.
 Short.
 Between adjacent Gyri.
 Long.
 Superior longitudinal
fasciculus.
 Inferior longitudinal
fasciculus.
 Cingulum.
 Fronto-occipital
fasciculus.

Commissural fibres.
 Corpus callosum.
 Anterior commissure.
 Posterior commissure.
 Habenular
commissure.
 Hippocampal
commissure.

Projection fibres.
 Afferents.
 Thalamic radiations
 Anterior.
 Posterior.
 Superior.
 Inferior.
 Efferents.
 Corticobulbar &
corticospinal tract.
 Cortico pontine
 Cortico Rubral
 Cortico Thalamic.

Internal capsule
 Thick curved band.
 Fans out up as corona
radiata & down as crus
cerebri.
 Most common part of
Infarction & Hemorrhage.
 Most common artery – Striate
branch of middle cerebral
artery so called Artery of
cerebral hemorrhage of
Charcot’s artery.

CEREBRAL CORTEX

More Related Content

What's hot

Similar to CEREBRAL CORTEX

More from Dr Nilesh Kate

Recently uploaded

In this document

CEREBRAL CORTEX