ARTERIAL AND VENOUS SUPPLY OF BRAIN

Part 2

Dr Sameeha Khan

Part 2

Cerebral arteries Vertebral artery Basilar artery

CEREBRAL ARTERIES

Distal ICA

Anterior cerebral artery Middle

cerebral artery

Basilar artery

Posterior cerebral artery

Anterior cerebral artery

A1 horizontal segment

• From ACA origin to ACoA junction.

• Inferior br – supply superior surface of optic nerve and chaisma.

• Superior br – anterior hypothalamus , septum pellucidum , anterior commisure , fornix , anterior inferior portion of corpus straitum.

Arise from A1 segment- perforating branches. • Pass cephalad

thro anterior perforated substance.

• Supply head of caudate nucleus and anterior limb of IC, putamen .

Medial lenticulostriate artery.

Recurrent Artery of Heubner

• Largest of the perforating branches.

• May arise from A1 or A2 segment.

• A1 – 44%• Proximal A2 – 50%• ACoA – less common • Derives its name from

the fact that it doubles back on its parent artery at an acute angle to join lenticulostriate vessel.

• Lies parallel to A1 .

A2 segment- Interhemispheric segment

From ACoA junction

Ascend in front of 3rd ventricle in cistern of lamina terminalis

br –Orbitofrontal, frontopolar

Curves around corpus callosum genu gives terminal branches

A2 terminal

branches-

Pericollasal

Collasomarginal

Cortical A3 segment

• Supply the anterior 2/3rds of medial hemispheric surface + small superior area over the convexities.

• Callosomarginal a.– lies in cingulate gyrus supplies medial frontal lobe

• Pericallosal a.– course along the posterior aspect of corpus callosum and supplies it and medial parietal lobe

Cortical branches – territories

Lateral DSA mid arterial phase

A1

A2

A3

orbitofrontal

Callosomarginal Pericollasal

Medial lenticulostriate Recurrent

artery heubner

Pericollasal

A2

Orbitofrontal

Frontopolar

A3

Callosomarginal

AP DSA mid arterial

3D MRA

A2

Pericollasal

Callosomarginal

ACA– ACoA complex

ACoA -Part of COW -not a true branch of ACA

Branches – perforating Supply –Lamina terminalis

, Hypothalamus , Anterior commissure , Fornix, Septum pellucidum , Para olfactory gyrus , Subcellosal region , Anterior part of cingulate gyrus

Variants -ACoA

ACA – ACoA complex – normal 1/3rd anatomy dissection

Absent , duplicate or multichannel ACoA – 10-15%

• Hypoplasia or absent A1 ACA segment-distal segments fill preferentially from other side via ACoA.

Variants – A1

Duplication ACA

Fenestration / duplication of ACA

Azygous ACA – solitary unpaired vessel Single trunk from confluence of A1 segments of right n left

ACAs- supplies both hemispheres . Assc with lobar holoprosencephaly, saccular aneursym

• Normally A1 segment runs over the optic nerve.

• Here it runs below the optic nerve.

• Assc with aneurysms .

• Recognised before surgeries.

Infraoptic origin of ACA

Variable branches to C/L hemisphere.

Separate right n left ACA.

1 ACA is dominant than other and it sends branches to other hemisphere.

Other ACA is hypoplastic – terminate as orbitofrontal or frontopolar branch.

Bihemispheric ACA

Middle cerebral artery

M1 horizontal

Origin -Laterally from ICA

bifurcation

Till its bi/trifurcation at sylvian fissure. Br – Lateral Lenticulostriate branch course

superiorlyAnterior

temporal artery Supplies-Lentiform nucleus

Part of IC , caudate nucleus

M2 insular

At its genu divides into branches

Loop over insula pass laterally to exit from sylvian

fissure

M3 opercular

Emerge from sylvian fissure

Ramify over hemispheric

surfaceSupplies –cerebral cortex and white

matter

Cortical branches

1. Orbitofrontal artery (lateral frontobasal )

2. Prefrontal arteries 3. Precentral

(prerolandic )4. Central sulcus

(rolandic) 5. Postcentral sulcus

(anterior parietal) artery

6. Posterior parietal artery

7. Angular artery 8. Posterior temporal 9. Temporooccipital

artery 10. Medial temporal

AP DSA mid arterial phase

AP DSA early arterial phase

Early arterial phase

Lateral DSA Mid arterial phase

Lateral

•M1 horizontal •MCA bifurcation •M2 insular •M3 opercular

CT

MRA

Lateral Lenticulostriate Artery

• Origin - M1 • Supplies – • Part of head

and body of caudate

• Globus pallidus

• Putamen • Posterior

limb of internal capsule

Sylvian segment territory

• Supplies • Inferolateral

frontal lobe • Insular

cortex • Parietal lobe • Temporal

lobe

Cortical segment territory

• Supplies – • Lateral

cerebrum • Insula • Ant-

lateral temporal lobe

Variants- MCA

Less frequent Fenestration and duplication Single trunk Accessory arteries

All uncommon ≤5 %

MCA fenestration

Accessory MCA

• It is either hypertrophied RA heubner or medial ACA perforator.

• To be called accessory MCA it should have cortical branches.

PCA origin from bifurcation of basilar artery in interpeduncular cistern.Lies above occulomotar nerve. Circles midbrain above tentorium cerebelli.

Posterior cerebral artery

Posterior cerebral artery

P1 precommunicating / peduncular

•Basilar bifurcation extends laterally •Junction with PCoA•Br – •Post thalamoperforating-thalamus , midbrain •Medial posterior choroidal artery – anteromedially along roof of 3rd ventricle –tectal plate , midbrain , thalamus posterior , pineal gland , tele choroidae of 3rd ventricle.

P2 ambient / crural

•PCA- PCoA junction posterior •Above trochlear nerve and tentorial incisura •Br – •Thalamogeniculate arteries- MGB , pulvinar , brachium superior colliculus , crus cerebri , LGB •Lateral post choroidal artery – over pulvinar of thalamus – posterior thalamus , lateral ventricular choroid plexus

Inferior temporal artery • Undersur

face of temporal bone

• Anastamose -MCA

Parietooccipital artery• Posterior

1/3rd interhemispheric surface

• ACA

Calcarine artery( P4 )• Visual

cortex• Occipital

pole

Posterior pericollasal artery (splenial)• Splenium

of corpus callosum

• ACA

AP DSA

AP DSA mid arterial phase

Early arterial phase

Lateral DSA Mid arterial phase

MRA

CTA

Cortical territory

• Supply – • Medial

+posterior temporal lobe

• Medial parietal lobe

• Occipital lobe

Variant – PCA Fetal origin of PCA from ICA instead of basilar – 15-

20 % Carotid basilar anastomosis – supply PCA via

trigeminal artery or other persistent channels

Vertebral artery V1 Courses –Cephalad to enter transverse foramina

at C6

Ascend directly to C2 (V2)

Turns laterally and superiorly thro C1 vertebral

foramina

Looping posteriorly along atlas V3 extraspinal

Each VA passes superomedially thro foramen magnum In Posterior fossa anterior to medulla

(intradural )

VAs unite to form basilar artery

From subclavian arteriesLeft VA dominant 50%

Extracranial VA branches

1. V1-Small segmental spinal/ meningeal/ muscular branches.

2. V2- Anterior Meningeal artery , muscular branches.

3. V3 -Posterior Meningeal artery

Courses along posterior arch of atlas.

Supplies falx cerebri Variant – origin from ECA /

PICA. Greatly enlarged with

vascular malformations and neoplasms

Posterior meningeal artery

Intracranial VA branches

Vertebral artery

Anterior spinal artery

Medial medullary syndrome

Posterior inferior cerebellar artery

Arises from distal VA

Lateral medullary syndrome

Lateral DSA

AP DSA

V1- extraosseousV2 –foraminal V3 – extraspinal V4 – intradural

At c7 level At C6 level

At C1 C2 level

At spinal cord and pons level

Posterior inferior cerebellar artery

• Front of medulla Anterior medullary segment

• Along side of medulla caudally to level of CN 9-11

Lateral medullary segment

• Around inferior half of cerebellar tonsilTonsilomedullary

segment

• Cleft btw tela choridae and inferior medullary velum rostrally and superior pole of tonsil caudally

Telovelotonsillar segment

Cortical / hemispheric segment

Lateral DSA early arterial

Lateral DSA late arterial

Anterior medullary segment Posterior medullary segment Lateral medullary segment

• Choroid plexus of 4th ventricle.

• Posterolateral medulla.

• Cerebellar tonsil. • Inferior vermis. • Posteroinferior cerebellar hemisphere.

Supplies

PICA territory

Variants –

Persistent vertebrobasilar anastamosis

Left VA – aortic arch origin – 5%

Hypolastic VA – 40 %

Hypoplastic VA

Hypoplastic VA terminating as PICA

VA terminates in PICA – 1%

Duplicated VA

Orange arrow – duplicated VA Red – original VA from subclavian

VA duplication- ocassionally

Fenestrated VA

VA fenestration – occasionally

Extracranial PICA

Extradural origin of PICAPICA from VA below foramen magnum

Basilar artery

Right and left VA s unite – BA

Course cephalad in front of pons

Pontine cistern in the space delineated by lateral margin of clivus and dorsum sellae

Terminates in interpeduncular cistern

Divides into PCAs

•Average length – 3 cm •Width 1.5- 4 mm •Diameter <4.5 mm

BA - Branches

1. AICA – Anterior Inferior Cerebellar Artery

1st major branch. Posterior laterally in

cerebellopontine angle cistern toward the internal auditory canal. Here typically anteroinferior to facial and vestibulocochlear nerve.

Few mms from origin AICA crossed by abducens nerve.

Supplies- ▪ Nerves ▪ Inferolateral pons ▪ Middle cerebellar peduncle ▪ Flocculus ▪ Anterolateral cerebelllar hemisphere

BA –branches

2. SCA- Superior Cerebellar Artery –

Arises from BA apex. Posterolaterally around Pons

and mesencephalon below tentorial incisura and CNS 3 n 4.

Supplies – ▪ Superior surface of vermis n

cerebellar hemisphere. ▪ Deep cerebellar white matter. ▪ Dentate nucleus.

Perforating branches – short n long segment

BA – terminates into PCA s

AP DSA

MRA

Variants - Nonfused basilar

Variants -Basilar fenestration

Variants -AICA duplication

Variants -SCA origin from PCA / ICA directly

SCAs- can arise from P1 segment