Anatomy Atlas

Cerebral arteries (ACA, MCA, PCA)

Arteria cerebri anterior, media et posterior
Also: Anterior cerebral artery · Middle cerebral artery · Posterior cerebral artery · ACA · MCA · PCA · Stroke syndromes · Ischemic stroke
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The three paired arteries that supply the cerebral hemispheres. Each territory gives a recognizable stroke syndrome; the MCA is the most commonly affected.

Core anatomy

Origin

ACA and MCA are the terminal branches of the internal carotid artery (common and internal carotid arteries); the PCAs are the terminal branches of the basilar artery (vertebrobasilar system); all are linked by the circle of Willis.

Course

ACA runs forward above the optic chiasm into the longitudinal fissure and arches back over the corpus callosum along the medial surface. MCA runs laterally in the lateral (Sylvian) fissure, giving the lenticulostriate arteries, then superior and inferior divisions over the lateral surface. PCA curves around the midbrain to the occipital lobe and inferior temporal lobe.

Branches
  • ACA: recurrent artery of Heubner, orbitofrontal, callosomarginal, pericallosal
  • MCA: lenticulostriate arteries (basal ganglia, internal capsule), superior division (frontal — Broca, motor face/arm), inferior division (temporal/parietal — Wernicke, optic radiations)
  • PCA: thalamoperforating and thalamogeniculate branches, posterior choroidal, temporal and calcarine branches
Supplies

ACA: medial frontal and parietal lobes — motor/sensory cortex for the leg and foot, bladder control, corpus callosum. MCA: most of the lateral hemisphere — face and arm motor/sensory cortex, language areas (dominant), spatial attention (nondominant), optic radiations; deep structures via lenticulostriates. PCA: occipital lobe (visual cortex), inferior temporal lobe (hippocampus), thalamus, midbrain.

Anastomoses

Leptomeningeal (pial) collaterals link the ends of the territories — the watershed zones between ACA–MCA and MCA–PCA.

Structures supplied

Mentioned in

Generated automatically from links in other entries.

Territories of the cerebral arteriesLateral surface of the left hemisphere: the middle cerebral artery supplies most of the lateral surface including the face and arm areas of the motor and sensory cortex and the language areas; the anterior cerebral artery supplies a strip along the superior border; the posterior cerebral artery supplies the occipital pole and the inferior temporal lobe. Medial surface of the right hemisphere: the anterior cerebral artery supplies the medial frontal and parietal lobes including the leg area (paracentral lobule); the posterior cerebral artery supplies the occipital lobe around the calcarine sulcus.ACAMCAPCALegArmFaceLateral fissureCentral sulcusLateral surface, left hemisphereACAPCALeg/foot (paracentral lobule)Calcarine sulcus (V1)Corpus callosumMedial surface, right hemisphereACAMedial frontal/parietal — leg and foot, bladderMCALateral surface — face and arm, language, attentionPCAOccipital lobe (vision), inferior temporal lobeFrontal pole on the left in both views. Territory borders (watershed zones) vary between people.

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Territories of the cerebral arteries. Lateral surface of the left hemisphere and medial surface of the right. The MCA supplies the face and arm cortex and the language areas; the ACA the medial leg area; the PCA the occipital lobe. Territory borders vary between people.
Original schematic, created for this atlas.
Circle of Willis and vertebrobasilar system (inferior view)Seen from below with the front of the brain at the top. The two vertebral arteries give the posterior inferior cerebellar arteries and join to form the basilar artery, which gives the anterior inferior cerebellar, pontine and superior cerebellar arteries and divides into the two posterior cerebral arteries. Posterior communicating arteries join each posterior cerebral artery to the internal carotid artery. Each internal carotid gives the middle cerebral artery laterally and the anterior cerebral artery medially; the anterior cerebral arteries are joined by the anterior communicating artery. The oculomotor nerve passes between the posterior cerebral and superior cerebellar arteries. Common aneurysm sites: anterior communicating artery, posterior communicating–internal carotid junction, and middle cerebral artery bifurcation.Anterior cerebral a.Anterior communicating a.Internal carotid a. (cut)Posterior communicating a.Middle cerebral a.Posterior cerebral a.Superior cerebellar a.Pontine branchesAICABasilar a.PICAVertebral a.Lenticulostriate aa.CN IIIInfundibulumBerry aneurysm sites: AComm, PComm–ICA, MCA bifurcationInferior view · anterior ↑

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Circle of Willis and vertebrobasilar system. Inferior view, anterior at the top. The internal carotids (anterior circulation) and basilar artery (posterior circulation) are joined by the communicating arteries; CN III passes between the PCA and SCA. Red dots mark common berry aneurysm sites. A complete, symmetric circle is present in only a minority of people.
Original schematic, created for this atlas.
Medial surface tinted by arterial territory: anterior cerebral (blue) over the medial frontal and parietal lobes, posterior cerebral (yellow) over the occipital and inferior temporal lobes, middle cerebral (pink) at the temporal pole
Medial surface of the hemisphere tinted by the territories of the cerebral arteries.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 518. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))
Inferior surface of the brain with the arterial circle, the basilar and vertebral arteries and the middle cerebral artery in the lateral fissure
The middle cerebral artery entering the lateral fissure.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 516. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

MCA stroke PANCE

Mechanism / lesion

Embolism (atrial fibrillation, carotid plaque) or thrombosis — the most common territory.

Classic presentation

Contralateral weakness and sensory loss of the face and arm more than the leg, contralateral homonymous hemianopia, gaze deviation toward the lesion. Dominant (left): aphasia. Nondominant (right): hemineglect, anosognosia.

ACA and PCA strokes PANCE

Mechanism / lesion

Embolic or thrombotic occlusion.

Classic presentation

ACA: contralateral leg > arm weakness and sensory loss, urinary incontinence, abulia/personality change. PCA: contralateral homonymous hemianopia with macular sparing, visual agnosia; dominant PCA + splenium → alexia without agraphia; thalamic involvement → sensory loss.

Acute ischemic stroke management PANCE

Mechanism / lesion

Time-critical reperfusion of the ischemic penumbra.

Classic presentation

Check glucose, noncontrast CT (exclude hemorrhage), NIHSS. IV thrombolysis (alteplase or tenecteplase) within 4.5 hours of last known well if no contraindications (BP must be < 185/110). Mechanical thrombectomy for large vessel occlusion (ICA, M1) — up to 24 hours in selected patients with CT perfusion/MRI. Then antiplatelet therapy, statin and a search for the source (ECG/telemetry, echocardiogram, carotid imaging).

High-yield PANCE pearls

  • Face/arm > leg weakness + aphasia (left) or neglect (right) → MCA.
  • Leg > arm weakness + incontinence → ACA.
  • Homonymous hemianopia with macular sparing → PCA.
  • Eyes deviate toward the lesion in a hemispheric stroke (away from the weak side).
  • IV thrombolysis ≤ 4.5 h; thrombectomy for LVO up to 24 h in selected patients.
  • Noncontrast CT first — hemorrhage must be excluded before thrombolysis.

Imaging anatomy

CT

Noncontrast CT (hemorrhage, early ischemic change, hyperdense MCA sign), CT angiography (large vessel occlusion), CT perfusion (core vs penumbra).

MRI

DWI is the most sensitive test for acute infarction.

Key views & landmarks
  • Stroke code: glucose → noncontrast CT → CTA ± CTP

Physical exam

Strength / function testing

NIH Stroke Scale (consciousness, gaze, visual fields, facial palsy, arm/leg drift, ataxia, sensation, language, dysarthria, neglect); compare face vs arm vs leg; check for aphasia, neglect and field cuts.

Self-quiz

Q1.

A 70-year-old with atrial fibrillation suddenly develops right face and arm weakness, right homonymous hemianopia, and difficulty producing and understanding speech. His eyes deviate to the left. Which artery is occluded?

Show answer

B

Contralateral face/arm weakness, field cut, aphasia (dominant hemisphere) and gaze toward the lesion point to a left MCA occlusion — likely cardioembolic.

Q2.

A 64-year-old develops weakness and numbness of the left leg, with only mild left arm weakness, and new urinary incontinence. Which artery is involved?

Show answer

A

The leg area of the motor and sensory cortex is on the medial surface, supplied by the ACA; a right ACA stroke causes left leg-predominant weakness and often incontinence.

Q3.

A 78-year-old has sudden loss of the left visual field in both eyes. Central vision is preserved, and there is no weakness. Which artery is most likely occluded?

Show answer

A

A left homonymous hemianopia with macular sparing and no weakness localizes to the right occipital lobe — right PCA territory.

Q4.

In an acute hemispheric (cortical) stroke, which way do the eyes usually deviate?

Show answer

A

A destructive hemispheric lesion knocks out the frontal eye field, so the intact opposite field drives the eyes toward the lesion, away from the hemiparesis.

Q5.

The lenticulostriate arteries supplying the basal ganglia and internal capsule arise from which artery?

Show answer

E

The lenticulostriate arteries are branches of the MCA. They are the vessels involved in lacunar infarcts and hypertensive hemorrhage of the putamen and internal capsule.

Flashcards

See also