This document provides an overview of the cerebral cortex, including its external features, functional areas, lobes, connections, and histological structure. It discusses the different areas of the cortex such as the frontal lobe (including the precentral, premotor, and prefrontal cortex), parietal lobe (primary and secondary sensory areas), temporal lobe (primary auditory and association areas), occipital lobe, and their functions. It also covers applied aspects like frontal lobe syndrome and temporal lobe syndrome.

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

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

3. Cerebral cortex
 External features.
 Cortical functional
areas.
 Phylogenetical division
of cerebral cortex.
 Histological structure.
 Areas , connections,
functions & applied
aspects.
Monday, March 2, 2015

4. External features.
 Poles.—
 Frontal
 Occipital
 Temporal.
 Surfaces
 Superolateral
 Medial
 Inferior.
 Borders.
 Superomedial
 Inferolateral
 Medial.
Monday, March 2, 2015

5. CEREBRAL CORTEX
 Sulci & Gyri.
 Surface area of cortex–
2200cm2
 Lobes of cerebral
hemispheres.
 Frontal – Motor.
 Parietal – Sensory.
 Temporal – Auditory.
 Occipital – Vision.
Monday, March 2, 2015

6. 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)
Monday, March 2, 2015

7. Cortical functional areas.
(Brodmann areas—47)
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)
Monday, March 2, 2015

8. Cortical functional areas.
(Brodmann areas—47)
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.
Monday, March 2, 2015

9. Monday, March 2, 2015

10. Monday, March 2, 2015

11. 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.
Monday, March 2, 2015

12. Histological structure.
 Cells
 Pyramidal cells.
(2/3rd
)
 Stellate cells or
Granule cells. (1/3rd
)
 Fusiform cells.
Monday, March 2, 2015

13. 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.
Monday, March 2, 2015

14. 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.
Monday, March 2, 2015

15. 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.
Monday, March 2, 2015

16. 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.
Monday, March 2, 2015

17. 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.
Monday, March 2, 2015

18. Areas .
 Frontal lobe
 Parietal lobe
 Temporal lobe
 Occipital lobe.
Monday, March 2, 2015

19. 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.
Monday, March 2, 2015

20. 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.
Monday, March 2, 2015

21. Primary Motor Area (4)
 Extent – from
Precentral gyrus to
Paracentral lobule on
medial surface.
 Characteristics –
 6 layers of cortex.
 Giant pyramidal cells
(Betz cells)
Monday, March 2, 2015

22. Topographic Representation.
 Contra lateral half of
body in inverted order.
 Part of body for skilled
movements – larger
area.
 Body represented
upside down.
Monday, March 2, 2015

23. Monday, March 2, 2015

24. 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.
Monday, March 2, 2015

25. Sensory Homunculi Motor Homunculi.

26. 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.
Monday, March 2, 2015

27. 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.
Monday, March 2, 2015

28. 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.
Monday, March 2, 2015

29. 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.
Monday, March 2, 2015

30. Connections of pre central cortex.
Afferents Efferents.
Monday, March 2, 2015

31. Prefrontal cortex.
 Major areas. (9-14,
23,24,29,32, 44-47.
Monday, March 2, 2015

32. 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.
Monday, March 2, 2015

33. 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.
Monday, March 2, 2015

34. 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.
Monday, March 2, 2015

35. 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.
Monday, March 2, 2015

36. Parietal lobe
 Primary sensory area.
(3,1,& 2)
 Secondary sensory
area.
 Sensory association
areas. (5, 7)
Monday, March 2, 2015

37. 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.
Monday, March 2, 2015

38. 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.
Monday, March 2, 2015

39. Sensory Association Areas. (5, 7)
 Post to area S1.
 Point to point
representation.
 Lesion – Tactile
Agnosia.
(Asteriognosis &
Tactile Aphasia)
Monday, March 2, 2015

40. 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.
Monday, March 2, 2015

41. 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
Monday, March 2, 2015

42. 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.
Monday, March 2, 2015

43. 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
Monday, March 2, 2015

44. 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.
Monday, March 2, 2015

45. 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.
Monday, March 2, 2015

46. 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.
Monday, March 2, 2015

47. Occipital lobe
 Primary visual cortex.
(17)
 Visual association
area. (18)
 Visual association area
or occipital eye field.
(19)
Monday, March 2, 2015

48. 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.
Monday, March 2, 2015

49. White matter of cerebrum.
 Association fibres.
 Commissural fibres.
 Projection fibres.
Monday, March 2, 2015

50. Association fibres.
 Short.
 Between adjacent Gyri.
 Long.
 Superior longitudinal
fasciculus.
 Inferior longitudinal
fasciculus.
 Cingulum.
 Fronto-occipital
fasciculus.
Monday, March 2, 2015

51. Commissural fibres.
 Corpus callosum.
 Anterior commissure.
 Posterior commissure.
 Habenular
commissure.
 Hippocampal
commissure.
Monday, March 2, 2015

52. Projection fibres.
 Afferents.
 Thalamic radiations
 Anterior.
 Posterior.
 Superior.
 Inferior.
 Efferents.
 Corticobulbar &
corticospinal tract.
 Cortico pontine
 Cortico Rubral
 Cortico Thalamic.
Monday, March 2, 2015

53. 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.
Monday, March 2, 2015

54. Thank
You