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