Transcript Blood Supply Human Neurobiology ANHB 2217 Avinash Bharadwaj

Blood Supply
Human Neurobiology
ANHB 2217
Avinash Bharadwaj
Semester 1, 2006
Week 2
Blood Vessels of CNS
Nervous tissue – high metabolic needs
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One-fiftieth of body weight
One-sixth of circulating blood volume
One-fifth of oxygen consumption
Extreme sensitivity to reduction or loss
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Seconds and minutes…!
The nature of arteries to the brain
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Thin walls
Susceptibility to vascular diseases
Cerebrovascular Disease
Narrowing of arteries (Stenosis)
Blocks in arteries
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“Plaques” and thrombi
Emboli
Rupture
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Weak wall / High Pressure
Aneurysm
Cerebrovascular Disease
“Atheromatous change”
Rough surface – clotting of blood
(thrombosis)
Clot or other matter coming in from
elsewhere – embolus
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Blood clots dislodged from other parts
Fat from fractures
Blocks and Bleeds
Blockage of an artery
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Transient or total
End arteries – no collateral
circulation
“Infarct”
Bleeding (Haemorrhage)
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Damage can be extensive
Bleeding outside the brain but
within
cranial
cavity…
pressure
Strokes
and
transient
ischaemic attacks
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Main Arterial Channels
Internal
carotid
Vertebral
(“Vertebrobasilar”)
Arterial Cast
Internal
carotid
Vertebral
(“Vertebro-basilar”)
Arterial Circle (of Willis)
ICA
ACA
MCA
PCA Cortical and central
branches
Basilar
SCA
AICA
Vertebral
PICA
Be careful with abbreviations!
The Arterial Circle
Can compensate for
slow blockage
Can equalise pressure
Variable pattern
Compensation is not
reliable!
Arteries – Courses
ACA
PCA
MCA
Cerebral
Arteries
Branches of middle
cerebral artery
Anterior cerebral
artery and its
branches
Branches of
posterior cerebral
artery
Arterial Territories
ACA
ACA
MCA
PCA
PCA
MCA
Superolateral surface
Medial surface
Think in terms of lobes and (later), functional areas
Localisation an important part of diagnosis.
Cortical and Central…
Cortical
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Longer, spread over the
surface
Central
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PM
AL
Short, slender
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Groups
Anterior
and
posterior
(medial + lateral in each group)
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AM
“Perforated substance”
Supply deeper structures
including basal nuclei,
diencephalon,
internal
capsule
and
even
midbrain
PL
Brainstem and Cerebellum
Vertebrobasilar system
“Cerebellar” arteries
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Supply cerebellum and parts of brainstem
Two inferior (“PICA” and “AICA)
One superior
Medullary, pontine and mesencephalic
branches
Spinal Arteries
Begin from the vertebral
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Anterior spinal artery (2  1)
Posterior spinal arteries
Reinforced by segmental arteries
Last slide!