BRAIN :VASCULAR ANATOMY

DR ARIF KHAN S

INTRODUCTION

About 18% of the total blood volume in the body circulates in the brain, which accounts for about 2% of the body weight.

loss of consciousness occurs in less than 15 seconds after blood flow to the brain has stopped, and irreparable damage to the brain tissue occurs in about 5 minutes.

Blood supply = arterial supply + venous drainage

ARTERIAL SUPPLY

Anterior circulation

Posterior circulation

Major vessels : Internal carotid ; Vertebral arteries

CIRCLE OF WILLIS

The circle of Willis (after the English neuroanatomist Sir Thomas Willis

Formed by

Vertebro-basilar system branches

Internal carotid and its branches

VERTEBRO BASILAR SYSTEMVERTEBRAL ARTERIES

Origin: Subclavian Arteries

Course: ascend through the transverse foramen of the upper six cervical vertebra.

Intracranial Entry via foramen of Magnum

VERTEBROBASILAR SYSTEM

BRANCHES

1. Anterior spinal artery

2. Posterior Inferior Cerebellar Artery (PICA)

3. Basilar Artery

oAnterior Inferior Cerebellar Artery (AICA)

oPontine arteries

oSuperior Cerebellar Artery

oPosterior Cerebral Artery

PICA

the largest branch of the vertebral artery arises at the caudal end of the medulla on each side

Runs a course winding between the medulla and cerebellum

It supplies

a. posterior part of cerebellar hemisphere

b. inferior vermis

c. central nuclei of cerebellum

d. choroid plexus of 4th ventricle

e. medullary branches to dorsolateral medulla

AICA

It arises from the basilar artery at the level of the junction between the medulla oblongata and the pons in the brainstem.

It passes backward to be distributed to the anterior part of the undersurface of the cerebellum, anastomosing with the posterior inferior cerebellar branch of the vertebral artery.

It supplies

a. the anterior inferior quarter of the cerebellum.

b. the middle cerebellar peduncle,

c. facial (CN VII) and vestibulocochlear nerves (CN VIII)

SUPERIOR CEREBELLAR ARTERY Branch of from lateral aspect of basilar artery

It supplies

a. most of the cerebellar cortex,

b. the cerebellar nuclei, and

c. The superior cerebellar peduncles

POSTERIOR CEREBRAL ARTERY P1 – pre communicating segment

Posterior thalamoperforating

Medial posterior choroidal

P2- ambient segments

Lateral posterior Choroidal

Thalamogeniculate arteries

Cortical branches

POSTERIOR CEREBRAL ARTERY

1. Central branches

Thalamoperforating & thalamogeniculate

supply the medial surfaces of the thalami and the walls of the third ventricle

Peduncular perforating branches

supply a considerable portion of the thalamus.

POSTERIOR CEREBRAL ARTERY2. Choroidal branches

Medial posterior choroidal branches

supply the tela chorioidea of the third ventricle and the choroid plexus

Lateral posterior choroidal branches

small branches to the cerebral peduncle, fornix, thalamus, and the caudate nucleus

POSTERIOR CEREBRAL ARTERY

3. Cortical branches

Anterior temporal & Posterior temporal

Lateral occipital

Medial occipital

Splenial or the posterior pericallosal branch

Supplies infero-medial part of the temporal lobe,

occipital pole, visual cortex, and

splenium of the corpus callosum

ANTERIOR CIRCULATION

Middle Cerbral artery

Anterior Cerebral artery

MIDDLE CEREBRAL ARTERY arises from the Internal Carotid

continues to lateral sulcus and divides into different branches

Course is divided into segments M1, M2 , M3 , M4

M1 from orgin to trifurcation

M2 from bifurcation to origin of cortical branches

M3 opercular branches (within sylvian fissure)

M4 emerges from sylvian fissure into surface of the hemisphere

MCA (BRANCHES)

M1-

•medial lenticulostriate penetrating arteries

•lateral lenticulostriate penetrating arteries (Charcot’s Artery)

•anterior temporal artery

•polar temporal artery

•uncal artery

MCA (BRANCHES) M2

Superior and inferior and some times to middle branch

Superior terminal branch

•lateral frontobasal (orbito-frontal) artery

•prefrontal sulcal artery

•pre-Rolandic (precentral) and Rolandic (central) sulcal arteries

Inferior terminal branch

•three temporal branches (anterior, middle, posterior)

•branch to the angular gyrus

•two parietal branches (anterior, posterior)

MCA(BRANCHES)

M3 – opercular branches

M4 - lateral branches to the surface

ANTERIOR CEREBRAL ARTERY

forms at the termination of the internal carotid artery

arches antro-medially to pass anterior to genu of the corpus callosum

It supplies medial aspect of the cerebral hemispheres back to the parietal lobe.

segments

•A1 - origin from the ICA to the anterior communicating artery (ACOM)

•A2 - from ACOM to the origin of the callosomarginal artery

•A3 - distal to the origin of the callosomarginal artery

ANTERIOR CEREBRAL ARTERY

A1- medial Lenticulo striater

A2 – Recurrent artery of Huebner. #

orbitofrontal artey

pericalossal artery

A3 – Terminal Cortical branches

Orbital branches

Supplies

oolfactory cortex

ogyrus rectus

omedial orbital gyrus

Frontal branches supply:

oCorpus callosum *

ocingulate gyrus

omedial frontal gyrus

oparacentral lobule

Parietal branches supply :

oprecuneus

INTERNAL CAPSULE BLOOD SUPPLY

INTERNAL CAROTID Ant. Choroidal artery

Supply lower part of posterior limb & retro-lentiform part

inferolateral part of the lateral geniculate body.

ACA Medial striate branch (Heubner’s)

the lower part of the anterior limb and genu of the internal capsule

MCA Lateral striate (lenticulostriate)

Supplies to the anterior

limb, genu, and posterior limb of the internal capsule

WATERSHED ZONES Area where the blood supply of cortical vessels overlap. These overlapping vessels are Terminal branches

Watershed Infarct:

An area of necrosis in the brain caused by an insufficiency of blood where the distributions of cerebral arteries overlap

WATER SHED INFARCTS

TERITORIAL SUPPLY (CROSS

SECTIONS)

ACA TERITORIES

MCA TERITORIES

PCA TERITORIES

Superior frontal gyrus

Middle frontal gyrus

Postcentral gyrus

Occipital lobe

Lateral ventricles

Corona radiata

Occipital lobe

Lateral horn

ThalamusInternal Capsule

Superior sagittal sinus

VENOUS DRAINAGE

EXTERNAL Veins

Superior Cerbral vein

Superficial & Deep middle Cerebral veins

INTERNAL

Thalamostriate veins

Choroidal veins

OTHERS

Veins draining from midbrain, pons, medulla, cerebellum

DURAL VENOUS SINUSES

EXTERNAL CEREBRAL VEINS

INTERNAL CEREBRAL VEINS

DURAL VENOUS SINUSES

DURAL VENOUS SINUSES

Structure:

The walls of the dural venous sinuses are composed of dura mater lined with endothelium

Name Drains to

Inferior sagittal sinus

Straight sinus

Superior sagittal sinus

Typically becomes right transverse sinus or confluence of sinuses

Straight sinusTypically becomes left transverse sinus or confluence of sinuses

Occipital sinus Confluence of sinuses

Confluence of sinuses

Right and Left transverse sinuses

Sphenoparietal sinuses Cavernous sinuses

Cavernous sinuses

Superior and inferior petrosal sinuses

Superior petrosal sinus

Transverse sinuses

Transverse sinuses

Sigmoid sinus

Inferior petrosal sinus

Internal jugular vein

Sigmoid sinuses Internal jugular vein

CAVERNOUS SINUS

Lateral to body of sphenoid bone

Lateral to body of sphenoid bone

Connected to opposite – intercavernous S

Receives blood

Middle cerebral V

Drains into

Int Jugular V –via Inf petrosal sinus

Transverse S – via Sup petrosal S

Dural Venous sinuses – emissary veins – extracranial V

THANK YOU Dr. Arif khan S

REFERENCE

Netter’s anatomy Atlas

Osborn

MRI Anatomy of Brain

Pubmed

webMD

Radiograpics.rsna.org