Blood supply to the brain Flashcards
What are the effects of hypoglycaemia to the brain?
mood change, confusion, dizziness. fainting
What are the symptoms of oxygen starvation to the brain?
light headedness, confusion, cyanosis, loss of consciousness, coma
What is unusual about brain arteries?
There are no anastamoses or safety methods for if blood supply is disrupted
How soon can neurons in an oxygen starved area become damaged?
As soon as 3 mins
What supplies the anterior brain?
the internal carotid arteries
What supplies blood to the posterior brain?
The vertebral arteries
How does the internal carotid enter the skull?
via the carotid canal
How do the vertebral arteries enter the skull?
via the foramen magnum
Where do the external carotid arteries arise?
from the carotid arteries
What is the role of the external carotid arteries?
Remain outside the skull and deliver oxygenated blood to the face, scalp, tongue, teeth, gums, sinuses, middle/external ear, pharynx, larynx, thyroid
What is the basilar artery?
The point at which the right and left vertebral arteries merge
Where is the basilar artery found?
At the pons
What branches come off the basilar artery?
those which supply the brainstem and the medulla
What happens at the point that the basilar artery terminates?
divides into the right and left posterior cerebral arteries (PCA)
What do the posterior cerebral arteries (PCA) supply?
the occipital lobe (including visual cortex) and inferior temporal lobe of each hemisphere
Where do the internal carotid arteries branch?
almost immediately as they enter the skull
What do the internal carotids divide into?
the middle cerebral artery and the anterior cerebral artery
What doe the middle cerebral artery supply?
most of the lateral surface of the frontal, parietal and temporal lobes
What corticies are supplied by the middle cerebral arteries?
motor, sensory, auditory, Wernickes, Brocas
How are teh right and left anterior cerebral arteries connected?
By the anterior communicating arteries
What does the anterior cerebral artery supply?
- 1cm strip on the superior edge of each hemisphere laterally
- medial surface of the frontal and parietal lobes
How does the vertebrobasilar system communocate with the internal carotid system?
Through the arterial circle of Willis
What forms the circle of Willis?
- One anterior communicating artery between the anterior cerebral arteries
- Two posterior communicating arteries between posterior cerebral arteries and internal carotids (or their branches)
How many people have all three communicating arteries?
About 60%
When can the circle of Willis operate as compensatory blood flow?
If the major blood vessels are obstructed before they reach the arterial circle
Where do the perforating arteries arise?
From the three pairs of arteries as they leave the circle of Willis on the underside of each hemisphere
What do the perforating arteries supply?
thalamus, internal capsule, basal ganglia
What are the features of the perforating arteries?
They are small and prone to CVA
