BloodBlood SupplySupply ToTo The Brain The BrainThe Cerebrospinal Fluid (CSF)The Cerebrospinal Fluid (CSF)

Dr MukhtarDr MukhtarNeurosurgery HMCNeurosurgery HMC

Extremly high demand for oxygen and nutrientsExtremly high demand for oxygen and nutrients: : Human Human brain represents 2% of the body weight, brain represents 2% of the body weight, butbut receives receives 18% of the cardiac output, 20% of total body oxygen 18% of the cardiac output, 20% of total body oxygen consumption and 25% of total body glucose utilization.consumption and 25% of total body glucose utilization.

Cerebrovascular deseases and strokeCerebrovascular deseases and stroke areare amongamong the the major causes of deathmajor causes of death..

Arteries Arteries supplyingsupplying the brain the brain

2 sources of blood:

ICA and VA

atlas

axis

Vertebro-basilar systemVertebro-basilar system CTA: CT angiography

C6

laterally

upward

backward

C2

C4

C5C6

(C3)

C7

cavernous sinus

C1

C2

C3

C4

C5C6

C7

ant. clinoid proc.

cavernous sinus

foramen lacerum

carotid canal

X-ray angiogram

caroticotympanic

inf. hypophyseal

ophthalmic

sup. hypophyseal

ant. choroidal

post. communicating

middle cerebralant. cerebral

ant. communicatingstriate

Circle of WillisCircle of Willis

Circle of Willis

Circle of Willis

oculomotor n.

abducens n.

optic chiasm

mamillary bodies

pituitary stalk

1. Circle of Willis encloses the optic chiasm, pituitary stalk and mamillary bodies.

2. Oculomotor nerve exits between the post. cerebral and sup. cerebellar arteries.

3. Vertebral arteries of the two sides unite to form the basilar artery at the ponto-medullary junction. The root of the abducens nerve and initial segment of the ant. inf. cerebellar artery can also be found here.

A1

A2

A1

ant. communicating

A2

A3

callo

som

argin

al b

r.

pericallosal br.

parietooccipital

sulcus

recurrent artery of Heubner

Heubner’s

A1

ant. communicating

A2

A3

callo

som

argin

al b

r.

pericallosal br.

parietooccipital

sulcus

recurrent artery of Heubner

M2M2

M3 M3

M3M3

ACA

MCA

PCA

parietooccipital

sulcus

PCA

anterior cerebral

middle cerebral

posterior cerebral

oculomotor n.PCA

sca

BA

VA

aica

picasca: superior cerebellar

aica: anterior inferior cerebellar

pica: posterior inferior cerebellar

Veins drainig the brainVeins drainig the brain

superior cerebral veins

inferior cerebral veins

Similarly, there are superior and inferior celebellar veins for the cerebellum.

superficial middle cerebral vein

SUPERFICIAL VEINS

Superior cerebral veins open into the superior sagittal sinus or into the adjacent lateral lacunae.

Inferior cerebral veins drain mainly into the sphenoparietal (1), cavernous (2), superior petrous (3), and transverse (4) sinuses.

1.2.

3.

4.

superior sagittal sinus

cavernous sinustransverse sinus

TROLARD’S VEIN

LABBE’S VEIN

ant. cerebral

deep middle cerebral

basal (Rosenthal)

great cerebral(Galen)

DEEP VEINS

of septum pellucidum

thalamostriate

choroid

*int. cerebral

great cerebral

ant.

cere

bral

deep middle cer.

basal

v. o

f sep

tum

pel

l.

thalamostriate

choroid

inte

rnal

cer

ebra

l

great cerebral vein

Almost the total volume of venous blood collected from Almost the total volume of venous blood collected from the brain leaves the skull through the jugular foramen the brain leaves the skull through the jugular foramen and the internal jugular vein.and the internal jugular vein.

If the jugular foramen and/or the internal jugular vein is If the jugular foramen and/or the internal jugular vein is occludedoccluded, , bloodblood may escape through the diploic and may escape through the diploic and emissary veins connecting the dural sinuses with the emissary veins connecting the dural sinuses with the veins of the scalp skinveins of the scalp skin..

Diploic veins (frontal, anterior and posterior temporal, occipital): form a network between the external and internal compact bony layers of the skull and connect dural sinuses with the external veins.

Emissary veins (occipital, parietal, condylar, mastoid): pierce the skull directly and connect dural sinuses with external veins.

diploicemissary

Blood-brain barrier (BBB)Blood-brain barrier (BBB)The extracellular fluid of the CNS is separated from the blood by the The extracellular fluid of the CNS is separated from the blood by the BBB ensuring strictly controlled and mainly carrier protein assisted BBB ensuring strictly controlled and mainly carrier protein assisted transport of macromolecules.transport of macromolecules.

Is formed by endothelial cells attached to one other by tight junctions, Is formed by endothelial cells attached to one other by tight junctions, basement membrane, astrocytic endfeet.basement membrane, astrocytic endfeet.

Protects the CNS from possibly toxic agents.Protects the CNS from possibly toxic agents.

the Circumventricular organs

““Circumventricular”Circumventricular” = = around the ventriclesaround the ventricles

Incomplete or missing BBBIncomplete or missing BBB

Highly capillarized structuresHighly capillarized structures

Secretion of neurohormones or detection of Secretion of neurohormones or detection of hormones, glucose, ions, etc.hormones, glucose, ions, etc.

Subfornical organ sensory fluid regulation

Organum vasculosum

sensory, secretory

detects peptides, fluid regulation

Median eminence secretoryregulates the anterior pituitary through the release of neurohormones

Neurohypophysis secretorystore and secretes the hormones oxytocin and ADH into the blood, but does not synthesize either hormone

Subcommissural organ

secretory secretes certain proteins into the cerebrospinal fluid, its specific function is as yet unknown.

Pineal gland secretory stimulated by darkness to secrete melatonin and is associated with circadian rhythms

Area postrema sensory

the vomiting centre of the brain (can detect noxious substances in the blood and stimulate vomiting in order to rid the body of these toxic chemicals)

The cerebrospinal fluid (CSF)The cerebrospinal fluid (CSF)

Provides mechanical protection for the brain and the Provides mechanical protection for the brain and the spinal cord.spinal cord.

When floating in the CSF brain weighsWhen floating in the CSF brain weighs only 50g (!) only 50g (!) according to the Archimedes’ principle.according to the Archimedes’ principle.

internal and external CSF spaces

internal = ventricles external = subarachnoidal space

Surface of a choroid plexus

ant. choroidal from ICA or MCA

post. choroidal from PCA

choroidal a. of the 4th ventricle from pica

median aperture of Magendi

cerebellomedullary(or great) cystern

lateral aperture of Luschka

lateral pontine(or pontocerebellar) cystern

Site of CSF resorption: arachnoid granulations in the superior sagittal sinus and lateral lacunae.

Figure Midbrain “face of panda” due to neurocysticercal granulomaAxial fluid-attenuated inversion recovery (A) and T2-weighted (B) MRI of midbrain reveal a cyst with mural nodule,

in the periaqueductal grey matter, ventral to the aqueduct.

Konanki R et al. Neurology 2013;80:1999-1999

© 2013 American Academy of Neurology

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