Dr.Mohammed Sadiq Azam

Postgraduate, Prof.Siraj’s unit, M:I

Deccan College of Medical Sciences

ANTERIOR CEREBRAL

CIRCULATION

BRAIN - ANATOMY

BRAIN - ANATOMY

BRAIN - ANATOMY

ANTERIOR CIRCULATION

• Internal Carotid Artery -

main artery

• Terminates into :

• Anterior cerebral

artery

• Middle cerebral artery

• Forms the crux of the

anterior circulation.

MIDDLE CEREBRAL ARTERY (MCA)

MIDDLE CEREBRAL ARTERY (MCA)

• Supplies most of the temporal lobe, anterolateral frontal lobe, and parietal lobe.

• Perforating branches supply the posterior limb of the internal capsule, part of the head and body of the caudate and globus pallidus.

• Unilateral occlusion of Middle Cerebral Arteries at the stem (proximal M1 segment) results in:• Contralateral hemiplegia affecting face, arm, and leg (lesser).• Homonymous hemianopia - Ipsilateral head/eye deviation.• If on left: global aphasia.

• Usually occlusion is embolic in nature - thrombotic occlusion more common in carotids.

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. 

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).

MCA – (M 2) Sylvian segment

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

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.

MCA – (M 3) Cortical segment

• Distal branches of MCA

course laterally to insular

cortex and loop around

operculum - "Candelabra"

effect seen on lateral

angiograms.

• Embolization of

individual cortical

branches can produce

highly circumscribed

infarctions accompanied

by specific neurologic

deficits.

ANTERIOR CEREBRAL ARTERY (ACA)

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

caudate and anterior globus pallidus.

ANTERIOR CEREBRAL ARTERY (ACA)• Bilateral occlusion of Anterior Cerebral Arteries at

their stems results in infarction of the anteromedial

surface 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

humunculus)

ACA – A 1 SEGMENT

• From Internal Carotid Bifurcation to Anterior Communicating Artery.

• A1 Branches: Anterior Communicating Artery(connects both sides of anterior circulations).

Medial Lenticulostriate Arteries(supply basal ganglia, anterior limb of internal capsule).

Recurrent Artery of Heubner(supplies head of caudate and anteroinferior internal capsule)

ACA – Anterior communicating art

• Connects bilateral anterior circulations.

Common location for cerebral aneurysms.

ACA – Recurrent artery of Heubner

• Supplies head of caudate and anteroinferior internal capsule.

ACA – Pericallosal artery

• Continuation of the Anterior Cerebral Artery as it arches superiorly and posteriorly.

Supplies the medial surface of the cerebral hemispheres and corpus callosum.

ANTERIOR CHOROIDAL ARTERYArises from ICA (rarely from MCA also)

The anterior choroidal artery serves many

structures 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

• crus cerebri

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

CIRCLE OF WILLIS• Communication between the anterior and posterior

circulations

WATERSHED AREAS

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

THANK YOU