2. Introduction
• Cardiac output is about 5 L of blood
• The brain comprises only 2% of body weight, but receives 15% of
cardiac output and uses 20% of total body oxygen and 25% of total
body glucose
• Carotid system (Anterior system)
• Vertebro-basiler system (posterior system)
3. BLOOD SUPPLY TO BRAIN
• The blood vessels supplying brain are two internal carotid arteries
and two vertebral arteries.
• Carotid artery contributes approximately 80% to the total cerebral
blood flow, the remaining 20% coming from the two vertebral
arteries
10. Anterior Cerebral Artery
• Occlusion of anterior cerebral artery : contralateral paralysis and
sensory deficits in the leg and perineum, urinary incontinence. Often
with mental confusion.
17. VERTEBROBASILAR SYSTEM
• Vertebral artery, branch from the subclavian artery, joins together to
form the basilar artery. The latter artery splits into posterior cerebral
arteries
• Branches off the vertebral artery :
1. spinal artery: anterior spinal artery: one formed by branches from
each vertebral artery
2. posterior spinal artery: one on each side
3 . posterior inferior cerebellar artery (PICA) largest branch off vertebral
artery, supplies cerebellar hemisphere, inferior vermis
18.
19. Basilar artery
• Branches off basilar artery
1. anterior inferior cerebellar artery (AICA) supplies inferior surface of
the cerebellum
2. labyrinthine artery supplies the membranous labyrinth of the
internal ear
3. Pontine arteries supply pons and pontine tegmentum
4. superior cerebellar artery supplies pons, superior cerebellar
peduncle, and inferior colliculus, etc.
21. Circle of Willis
• Consists:
• anterior communicating, anterior cerebral, internal carotid (short
segment), posterior communicating, and posterior cerebral arteries.
• Normally not too much blood flow, could be served as alternative
route if one of the artery in occluded
• Common site for aneurysms, terminal part of internal carotid artery
anterior communicating artery proximal of middle cerebral artery
24. What happens when blood supply to brain is reduced?
• Certain functional changes occur once blood flow to the brain
decreases.
• Critical values for loss of synaptic transmission, corresponding to loss
of neuronal function, are between 15 and 18 ml/100 gram/minute
• The threshold for membrane pump failure. and thus for loss of
cellular integrity and cell death, is approximately 10 ml/100 gram/
minute
• It is generally assumed that if CBF stays above 18 ml/100 g/min but
below 20–25 ml/100 g/min neurons will survive but may not
function
