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Brodmann numbered different areas of
cerebral cortex. Based on function,
2 types of areas:
1) Sensory areas (located in post central gyrus,
superior temporal gyrus & part of hippocampal
gyrus & contain granular cortex)
2) Motor areas (located in pre central gyrus & in
other parts of frontal lobe & contain mainly
agranular / pyramidal cortex)
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1) ELECTRICAL STIMULATION OF DIFFERENT
PARTS OF MOTOR AREAS : & movement of
different parts of body is noted.2)ABLATION METHOD: A part of motor cortex is
damaged & motor loss is noted.
3) CLINICO-PATHOLOGICAL STUDY OF
DISEASE: Post-mortem findings co-related toclinical loss of motor activity.
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1) PRIMARY MOTOR AREA
2) PRE MOTOR AREA
3) SUPPLEMENTARY MOTOR AREA
4) SPECIAL MOTOR AREAS
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MOTOR AREAS Brodmanns no:
Primary motor area 4
Pre motor area 6
Supplemental motor area 8, 9, 10
Brocas area / Motor
speech area
44, 45
Frontal eye field 8
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LOCATION: Lies in first convolution of frontal
lobes anterior to central sulcus. It begins
laterally in the sylvian fissure, spreads
superiorly to uppermost portion of brain & then
dips deep into the longitudinal fissure. It is
brodmanns area 4.
It consists ofagranular type of cerebral cortex.In this area in layer no: 5, there are giant
pyramidal cells called Betz cells
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There is topographical (parts by parts)
representation of body & contralateral as well
as upside down representation. By joining
these parts, a figure of the body is formed:
MOTOR HOMUNCULUS. It is a mirror image
ofSENSORY HOMUNCULUS.
Parts of body concerned with precise, fine &skilled movements, are represented by
much larger area.
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Coordinated movement of contra-lateral
parts of body.
Blood flow to motor cortex varies withmotor activity of different parts of body,
e.g, if right hand is moved, blood flow to
hand representation area in left motorcortex is increased (because ofcontra-
lateral control)
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AFFERENT CONNECTIONS:
Receives afferents from primary motor area ofopposite side &
Afferents from premotor & supplementarymotor areas &
Afferents from somatic sensory, auditory &
visual areas & Afferents from thalamus, basal ganglia &
cerebellum.
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EFFERENT CONNECTIONS:
Efferents to spinal cord as corticospinal tract.
Efferents to cranial nerve nuclei (corticobulbarfibers).
Efferents to thalamus.
Efferents to basal ganglia.
Efferents to cerebellum as cortico-ponto-
cerebellar fibers.
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LOCATION:Anterior to primary motor
area. It extends 1-3 cm anteriorly.
It is broad at top & narrow below.
At the top it extends upto longitudinal
fissure & below upto sylvian fissure /
lateral fissure.
It consists of superior, middle & inferior
frontal gyri. It is brodmanns area 6.
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In this area there is also topographical representation of
different parts of body & pattern is similar to that inprimary motor area.
When pre motor area is stimulated there aremovements involving contraction of groups of muscle.
This area is connected with primary motor area, directlyor indirectly through basal ganglia & then throughthalamus.
This area programs the activity of primary motor areawith the help of patterns already stored in brain.
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LOCATION: Lies mainly in the longitudinal fissure but
extends a few centimeters onto superior
frontal cortex. It contains medial frontal gyrus.
In this area different parts of body are
also represented. Face is anterior, legs are posterior, back
is in superior wall of singulate sulcus.
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When this area is stimulated, movement oflimbs or other parts on both sides (bilateral
movement).
Bilateral grasping movement.
This area controls the attitudinal, positional orfixation movements, e.g, background posturerequired for climbing up.
It supplements finer motor control areas (premotor & primary motor) by positionalmovements of head, eyes etc.
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LOCATION: In inferior frontal gyrus, justanterior to face representation area in primary
motor cortex.
It is brodmanns area 44, 45.
It is just above latral sulcus / sylvian fissure.
In this area detailed motor pattern for
contraction of muscles of phonation &
articulation is formed
.
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Then impulses are sent from this area toprimary motor area to initiate these
contractions. This area recieves impulses from
Wernickes area through arcuatefasiculus.
Spoken speech parts:
1) Phonation (to initiate vocal cord
vibration, these must be adducted)
2)Articulation
3) Resonance
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MOTOR APHASIA: Difficulty in utteringwords & speech is limited to only few
words.
Also called NON-FLUENT APHASIA. Damage does not prevent vocalizing.
May utter a simple word such as no or
yes. Impossible to speak whole words.
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LOCATION: In the pre motor area immediately aboveBrocas area is a locus for controlling voluntary eyemovements.
It is brodmanns area 8.
When this area is electrically stimulated, there is
conjugate deviation of eyes towards opposite side.
Similar area is also present in occipital lobe.
Frontal eye field also controls eye-lid movements likeblinking. When this area is damaged, person cannotmove eyes from one object to other.
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3) HEAD ROTATION AREA:
Near frontal eye field, slightly higher in motorassociation area.
Controls rotation of head. Electrical stimulation elicits head rotation
It directs the head towards different objects.
4)AREA FOR HAND SKILLS: In the premotor area, immediately anterior to primary
motor cortex for hands & fingers.
Controls hand skills.
When this area is damaged by tumors or otherlesionsMOTOR APRAXIA. Hand movementsbecome uncoordinated & non-purposeful.
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BROCAS
AREA
PRIMARY MOTOR
W. Area
CORTEX
ADDUCTORS
OF
VOCAL
CORDS
PHONATION
Pattern impulses
Allows to contract
ARCUATE
FASICULUS
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