Cortical areas of brain by Brodmann

1. DR PRATIK MISTRY

4.  Allocortex – 10 % (also called Limbic Cortex)
i. Archipallium – hippocampus & Dentate gyrus.
ii. Paleopallium – Uncus & part of Parahippocampal
gyrus.
iii. Mesocortex. – transitional zone.
 Neocortex (Isocortex) -Rest of 90% of cerebral cortex.

5.  Six layers
1. Molecular
2. Outer granular
3. Outer pyramidal
4. Inner granular
5. Inner pyramidal
6. Pleomorphic
 Cells:
1. Pyramidal cells of betz
2. Granule (stelate) cells
3. Cells of martinoti
4. Horizontal cells of cajal

6.  AGRANULAR CORTEX
 Pyramidal cells – large,
Betz cells
 Granule cells absent or
less in number
 Seen in Motor cortex (4)
& Boca's motor speech
area (44)
 GRANULAR CORTEX
 Excess granule cells
 Few pyramidal cells
 Seen in sensory cortex &
visual area, auditory area

7.  FRONTAL CORTEX
 Small and medium
pyramidal cells
 Few stellate cells
 Pre-frontal cortex of
frontal lobe
 PARIETAL CORTEX
 More stellate cells
 Seen in most of parietal lobe &
junction of parietal, temporal &
occipital lobes
 POLAR CORTEX
 Thinnest of all
 All layers reduced depth.
 Seen in frontal & occipital pole

8.  For functional analysis, cerebral
cortex is divided into number
areas,
20 areas of Campbell
109 areas of Economo
200 areas of Vogt
52 areas of brodmann- frequently
used
 Subdivided into motor, sensory
and association areas

11.  Subdivided into
 Primary motor area (area 4)
 Pre-motor area (area 6)
 Frontal eye field (area 8)
 Supplementary motor area
 Pre-frontal area (areas 9 to 12)

12. Location:
 Precentral gyrus (area 4)
 Extends to the ant. part of
paracentral lobule
 Agranular cortex
Afferents :
 Premotor area (Area 6)
 Somesthetic or
somatosensory cortex
 Ant. Part ventral nucleus of
thalamus(which receives
info. from cerebellum
 Basal ganglia

13. Efferents :
 Fibres from area 4 and
area 6 forming…
1. Corticospinal
2. Corticonuclear
3. Corticobulbar tracts.
 Regulate the voluntary
movements of opposite
side of body
 Fronto-pontine fibres
 Corpus striatum, red
nucleus

14.  Control movements of
voluntary muscles of opposite
side
 Movements represented with
head end below and leg end up
(INVERTED MOTOR
HOMUNCULUS)
 Centres from below are: lips,
tongue, larynx, pharynx, face,
head & neck, upper limb with
large area for fingers and hand,
trunk, lower limb above knee.
 Ant. Part of paracentral lobule
 Extent of area depend on skill of
movement and not on the bulk
of muscle

15.  Somewhat sensory. Receive some sensations like
tingling and numbness
 Known as MSI
 Muscles of forehead, tongue, mastication, larynx,
pharynx, extra ocular bilaterally represented
 Only movements not muscles
 LESION: initially flaccid paralysis

16. Location (area 6):
 In front of area 4, include
post. Part of sup., middle
and inf. Frontal gyri
 On medial side, continue
with supplementary motor
area
 Agranular & motor

17.  Integrates voluntary movements to perform skilful act.
 Writing centre
 Concerned with programming which is executed by
area 4
LESION:
 Produce difficulty in the performance of skilled
movements.
 Apraxia: loss of the ability to do simple or routine acts
in the absence of paralysis.
 Agraphia: when writing is also involved.

18. PRIMARY SOMATOMOTOR
AREA (MSI)
=
PRIMARY MOTOR AREA
PREMOTOR AREA

19.  Lie in front of area 6
 Involve posterior part of middle
frontal gyrus
 Agranular cortex
 Regulate voluntary conjugate
movements of eye. Deviation of
eyes to the opposite side
 Controls voluntary scanning
movements of the eyes and is
independent of the visual
stimuli.
 Connected to the visual area of
occipital cortex by association
fibres.
 Lesion of the area cause two eye
to deviate to the side of lesion

20.  Located on medial surface
of cerebrum in the post.
part of medial frontal gyrus
anterior to the paracentral
lobule
 Afferents from VA and VL of
thalamus
 Efferents to area 4
 Function is to control
complex movements.
Produce sensation of “URGE
TO MOVE’
 Receive some senses (MSII)
 Lesion of area produce
AKINESIA

21.  Rest of frontal lobe ant. to pre-motor
area which include orbital surface also
 Fibres from thalamus, hypothalamus,
limbic system, all areas of cortex
 Concerned with individual’s
personality
 Regulate depth of feeling, thinking,
mature judgement, orientation,
concentration, pleasure and
displeasure, right or wrong.
 Bilateral damage due to trauma or
tumour: change in personality, loss of
concentration, judgement,
inappropriate social behaviour like
vulgarity of speech, improper clothing

22. Primary Secondary Sensory Association
Somesthetic (sensory) Visual Auditory

23.  Primary somesthetic
areas (areas 3,1,2)
 Secondary somesthetic
area
 Somesthetic association
are (areas 5,7)

24.  Located in the post-central
gyrus and extends into the
posterior part of the
paracentral lobule on the
medial surface.
 Granular cortex
 Afferents from VPL and
VPM of thalamus and other
areas of cortex

25.  Localise, analyse, discriminate
all modalities of sensations
 Sensations represented with
head end below (INVERTED
SENSORY HOMUNCULUS)
 Paracentral lobule receive
sense of distension from
bladder and rectum
 Hand, face, tongue, lips having
larger representation in cortex
 Lower part act as taste centre
(area 43)
 Modulate sensory input
 Secondarily motor (SMI)

26.  Located on the posterior part of posterior ramus of
lateral sulcus
 Involve lower part of pre and post-central gyri
 Receive mainly pain sensation
 Somewhat motor in function (SMII)

27.  Located in the superior
parietal lobule
 Connected with higher
association area in supra-
marginal gyrus (area 40)
 Concerned with the
perception of shape, size,
roughness, and texture of
the objects
 Stereognosis- ability to
identify known objects in
hand with closed eyes
 Astereognosis or Tactile
agnosia

28.  Primary visual area
(area 17)
 Visual association
area (area 18 & 19)
 Higher visual
association area
(area 39)

29.  Located in the lips and walls
of posterior part of calcarine
sulcus which include cuneus
and lingual gyrus
 Thinner and granular cortex
 Stria of gennari
 Afferents from optic radiation
 Temporal half of same retina
and nasal half of opposite
retina
 Register opposite field of
vision

30. Macular area-
 occupying approximately
posterior one-third of the
visual cortex.
 is the central area of retina
and responsible for maximum
visual acuity (keenest vision)
has extensive cortical
representation
 Connected to area 18, 19 of
both sides
 Concerned with reception and
perception of simple visual
impressions like colour, size,
form, transparency etc.

31.  Unilateral lesion due to
thrombosis, trauma
produce partial blindness
(hemianopia) with
macular vision retained
 Macular sparing because
it is supplied by both
MCA and PCA

32.  Occupy rest of occipital
lobe and calcarine sulcus
 Afferents from area 17
 Occipital eye field-
produce involuntary
deviation of eyes reflexly

33.  Located in the angular gyrus
of inferior parietal lobule
 It relate visual information
to the past experience, thus
enabling person to
recognize and identify the
object by vision
 Lesion of this area- visual
agnosia- inability to
recognize known objects by
vision
 Sensory aphasia (word
blindness)- inability to
recognize written word

34.  Primary auditory
area (area 41)
 Auditory association
area (area 42)
 Higher auditory
association area
(Wernicke's area)
(area 22)

35.  Involve anterior transverse
temporal gyrus (of
Heschl), on the upper part
of sup. temporal gyrus
 Granular cortex
 Afferents from MGB as
auditory radiation
 Detect the changes in
frequency and direction
from where sound
originates
 Unilateral lesion no
deafness due to bilateral
presentation

36.  Lie behind area 41
 Involve posterior
transverse temporal
gyrus of superior
temporal gyrus
 Granular cortex
 Same function

37.  Wernicke’s area
 Rest of the area
 Afferents from area 41 &
42
 Interpretation of sounds
and comprehension of
spoken language from
past auditory experiences
 Lesion produce sensory
aphasia (word deafness)-
unable to interpret the
spoken words.

38.  Taste area (area 43)-
lower part of inf. parietal
lobule
 Vestibular area- lower
part post-central gyrus
near face area
 Olfactory area (area 28)-
anterior part of
parahippocampus gyrus
and uncus

39.  Speech- highly complex function
 Speech function performed by dominant hemisphere
 In 90%, left one, DOMINANT (TALKING BRAIN) &
right one, NON DOMINANT (MUTE BRAIN)
 FOUR SPEECH CENTRES: 3 sensory & 1 motor
 Sensory speech areas:
1. Area 22 (Wernicke's area)
2. Area 39
3. Area 40
 Broca’s motor speech area (area 44 & 45)

40.  Area 22 (Wernicke’s area)
 Interpret spoken language &
recognize familiar words
 Congenital deaf child-
dumb
 Area 39 of angular gyrus-
store visual images and
recognize them by sight
 Area 40 of supramarginal
gyrus- recognize familiar
objects by touch and
proprioception
 All these 3 areas receive
input from hearing,
vision, touch and process
it in the area 22 &
 Then project it to Broca’s
area through ARCUATE
FASCICULUS

41.  Located in the pars
triangularis and pars
posterior of inferior
frontal gyrus
 Afferents from area 22
 Efferents to the muscles
of tongue, lips, larynx,
pharynx, palate, face for
production of speech

42.  Area 22- word deafness- unable to interpret spoken
words. Speak fluently with incorrect and useless words
 Area 39- word blindness- inability to recognize
written words even written by self
 Alexia, Agraphia
 Area 40- Astereognosis
 Area 44 & 45- motor aphasia- cannot speak properly
although he understand everything. Slow speech with
many grammatical mistakes
 Conduction aphasia- arcuate fasciculus damage