cerebral vasculature Flashcards
What percentage of cardiac output, body O2 consumption, and liver glucose does the brain use despite only accounting for 2% of body weight?
10-20% cardiac output, 20% O2 consumption, 66% liver glucose
Where does blood supply to the vertebral artery (posterior) originate?
subclavian artery
where does blood supply to the internal carotid originate?
brachiocephalic then to common carotid
what term best describes the structure of the arteries of the brain?
anastomotic circuit
what is the circle of Willis?
anastomotic circuit of arteries at the base of the brain
what structure do the vertebral arteries fuse to form and where does this sit?
basilar artery, sits on the pons
what is the name of the main branch of the internal carotid?
middle cerebral artery
what is the advantage of the circle of Willis being an anastomotic circuit?
if there is an atherosclerosis in one area there is a chance of compensatory flow from the other side (communicating arteries)
Outline the order of venous drainage of the brain
cerebral veins drain into venous sinuses which drain into internal jugular veins
How does the venous system drain from the superior sagittal sinus to the jugular foramen?
superior sagittal sinus, confluence of sinuses, transverse sinuses, sigmoid sinus.
what is a thrombosis?
formation of a blood clot
What are the four types of haemorrhage in the brain?
extradural, subdural, subarachnoid, intracerebral
what is an extradural haemorrhage?
an arterial, high pressure hemorrhage usually due to trauma to the pterion, resulting in the dura being stripped away from the skull creating an extradural space.
what is a subdural haemorrhage?
a venous, low pressure haemorrhage in which the clinical effects may be delayed
what is a subarachnoid haemorrhage?
ruptured aneurysms often only found incidentally, are congenital, are relevant at the circle of Willis
If a subarachnoid hemorrhage is found incidentally, what determines whether it needs intervention?
if the patient is hypertensive then likely to intervene
What is an intracerebral haemorrhage?
spontaneous hypertensive haemorrhage in the brain parenchyma
what is a stroke?
a cerebrovascular accident defined as rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration
what are the two categories of stroke?
thrombo-embolic or hemorrhagic
What percentage of strokes are thrombo-embolic?
85%, 15% hemorrhagic
what is a transient ischaemic attack (TIA)?
a rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
what is an infarct?
dead tissue
define cerebral ischaemia
lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly
what is the difference between ischaemia and hypoxia?
ischaemia is a lack of blood flow, hypoxia is a component of ischaemia but specifically a lack of oxygen.
