areas n ant circ
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Dr.Mohammed Sadiq AzamPostgraduate, Prof.Sirajs unit, M:I
Deccan College of Medical Sciences
FUNCTIONAL ANATOMY OF THE
CEREBRAL HEMISPHERES &
ANTERIOR CIRCULATION
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BRAIN FUNCTIONAL
ANATOMY
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BRODMANNS AREAS
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ANTERIOR CIRCULATION
Internal Carotid Artery -
main artery
Terminates into :
Anterior cerebralartery
Middle cerebral artery
Forms the crux of the
anterior circulation.
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MIDDLE CEREBRAL ARTERY
(MCA)
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MIDDLE CEREBRAL ARTERY
(MCA)
Supplies most of the temporal lobe, anterolateralfrontal lobe, and parietal lobe.
Perforating branches supply the posterior limb ofthe internal capsule, part of the head and body ofthe caudate and globus pallidus.
Unilateral occlusion of Middle Cerebral Arteriesat the stem (proximal M1 segment) results in:
Contralateral hemiplegia affecting face, arm, andleg (lesser).
Homonymous hemianopia - Ipsilateral head/eye
deviation.
If on left: global aphasia.
Usually occlusion is embolic in nature -thrombotic occlusion more common in carotids.
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MCA (M 1) Horizontal segment Branch: Lateral lenticulostriate a
Unilateral occlusion of
Proximal M1 Segment
results in deficits in:
MOTOR
Contralateral Hemiplegia
(face and arm, lower extremity less affected.
SENSORY
Homonoymous Hemianopia + Deviation of head/eyes toward the
side of the lesion.
LANGUAGE
LEFT lesions: Global aphasia.
RIGHT lesions: Anosognosia.
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MCA (M 1) Lateral
lenticulostriate art.
Branch of M1 Segment of MCA.
Supplies basal ganglia structures:
Part of head and body of caudate, globus pallidus, putamen,and the posterior limb of the internal capsule.
Effect of lesion:
Damage to the internal capsule resulting in contralateral
hemiparesis and sensory deficit.
Speech may be affected (medial temporal lobe) as well as
visual function (Meyer's loop: optic radiations affected).
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MCA (M 2) Sylvian segment
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MCA (M 2) Sylvian segment
Divides into superior and inferior divisions: can be a site
for an embolus to lodge.
Branches supply:
Temporal Lobe and Insular Cortex (sensory language area
of Wernicke)
Parietal Lobe
(Sensory cortical areas)
Inferolateral frontal lobe
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MCA (M 2) Sylvian segment
Superior Division Infarction:
"Brachiofacial paralysis"Sensorimotor deficit involving face and arm, leg
to a lesser extent. Foot is spared.
Ipsilateral deviation of head/eyes.
With Left lesion may have initial global aphasia
-> motor aphasia.
No impairment of alertness.
Inferior Division Infarction:
Rarer than Superior Division Infarctions.Superior quadrantanopia / homonymous
hemianopia.
LEFT lesion: Wernicke aphasia (deficit in
comprehension of spoken/written language)
RIGHT lesion: Left-sided visual neglect.
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MCA (M 3) Cortical segment
Distal branches of MCA
course laterally to insular
cortex and loop around
operculum - "Candelabra"
effect seen on lateralangiograms.
Embolization of
individual cortical
branches can produce
highly circumscribed
infarctions accompanied
by specific neurologic
ANTERIOR CEREBRAL ARTERY
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ANTERIOR CEREBRAL ARTERY
(ACA)
ANTERIOR CEREBRAL ARTERY
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ANTERIOR CEREBRAL ARTERY
(ACA)
Supplies most of the medial surface of the
cerebral cortex (anterior three fourths), frontal
pole (via cortical branches), and anterior
portions of the corpus callosum.
Perforating branches (including the recurrent
artery of Heubner and Medial Lenticulostriate
Arteries) supply the anterior limb of the internal
capsule, the inferior portions of head of the
ANTERIOR CEREBRAL ARTERY
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ANTERIOR CEREBRAL ARTERY
(ACA) Bilateral occlusion of Anterior Cerebral Arteries at
their stems results in infarction of the anteromedialsurface of the cerebral hemispheres:
Paraplegia affecting lower extremities and sparing
face/hands.
Incontinence
Abulic and motor aphasia
Frontal lobe Symptoms: personality change,
contralateral grasp reflex.
Unilateral occlusion (distal to Ant. Comm. origin) of
Anterior Cerebral Artery produces contralateral
sensorimotor deficits mainly involving the lower
extremity with sparing of face and hands (think of the
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ACA A 1 SEGMENT
From Internal Carotid Bifurcation
to Anterior CommunicatingArtery.
A1 Branches:Anterior Communicating Artery
(connects both sides of anteriorcirculations).
Medial LenticulostriateArteries(supply basal ganglia,anterior limb of internal capsule).
Recurrent Artery ofHeubner(supplies head ofcaudate and anteroinferiorinternal capsule)
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ACA Anterior communicating art
Connects bilateralanterior circulations.
Common location forcerebral aneurysms.
ACA R t t f
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ACA Recurrent artery of
Heubner
Supplies head ofcaudate and
anteroinferiorinternal capsule.
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ACA Pericallosal artery
Continuation of theAnterior CerebralArtery as it arches
superiorly andposteriorly.
Supplies the medialsurface of thecerebral
hemispheres andcorpus callosum.
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ANTERIOR CHOROIDAL ARTERY
Arises from ICA (rarely from MCA also)
The anterior choroidal artery serves manystructures in the cerebrum:
choroid plexus of the lateral ventricle and third
ventricle
optic chiasm and optic tract
internal capsule
lateral geniculate body
globus pallidus
tail of the caudate nucleus, hippocampus,
amygdala
substantia nigra
red nucleus
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ANTERIOR CHOROIDAL ARTERY
Lesions lead to:
Contralateral hemiplegia
Contralaterial hemi-hypoaesthesia
Homonymous hemianopsia
Due to ischemic involvement of:
Internal capsule
Thalamus
Optic chiasm/Optic tract
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CIRCLE OF WILLIS
Communication between the anterior and posterior
circulations
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WATERSHED AREAS
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WATERSHED AREAS
There are two patterns of border zone infarcts:
Cortical border zone infarctions:
Infarctions of the cortex and adjacent subcortical white matter
located at the border zone of ACA/MCA and MCA/PCA
Internal border zone infarctions
Infarctions of the deep white matter of the centrum semi-ovale
and corona radiata at the border zone between lenticulostriate
perforators and the deep penetrating cortical branches of the
MCA or at the border zone of deep white matter branches of
the MCA and the ACA
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