Blood Supply to the Brain

Question 1

Blood supply to the brain depends on what two sets of arterial branches and which circulation do they provide?

Answer 1

Vertebral arteries- posterior circulation
Internal carotid arteries- anterior circulation

Question 2

what areas of the brain does the anterior and posterior circulations supply to?

Answer 2

anterior- cerebral hemispheres and diencephalon
posterior- brainstem, cerebellum, upper portion of the spinal cord, posterior forebrain and some deep structures.

Question 3

what are the major arteries that arise from the internal carotid (5) and the vertebral/basilar (6) arteries?

Answer 3

internal carotid-

Anterior cerebral arteries
Middle cerebral arteries
Anterior choroidal arteries
Posterior communicating arteries
Posterior cerebral arteries

vertebral/basilar-

anterior inferior cerebellar arteries (AICAs)
anterior spinal artery
basilar artery
posterior inferior cerebellar arteries (PICAs)
posterior spinal arteries
superior cerebellar arteries
vertebral arteries

Question 4

how does the circle of Willis form and where?

Answer 4

The basilar artery joins the blood supply from the internal carotids in an arterial ring at the base of the brain

in the vicinity of the hypothalamus and cerebral peduncles.

Question 5

Describe the circle of Willis starting from the basilar artery (4)

Answer 5

1. the basilar artery bifurcates to form the posterior cerebral arteries
2. the anterior system joins with the vertebral-basilar system through the posterior communicating arteries
3. the internal carotid arteries supply the middle and anterior cerebral arteries
4. the circle is completed by the anterior communicating artery which joins the two anterior cerebral arteries.

Question 6

where do the posterior cerebral arteries supply blood to?

Answer 6

regions in the posterior parietal lobe, inferior temporal lobe, and occipital lobe. Included in this region are primary and associational (higher-order) visual areas in each lobe and limbic regions in the posterior cingulate and parahippocampal gyri

deep branches supply the thalamus, posterior hypothalamus, choroid plexus of the third ventricle and the midbrain

Question 7

where do the middle cerebral arteries supply blood to?

Answer 7

superior division- portions of frontal and parietal cortex above the lateral fissure

inferior division- portions of temporal and parietal cortex below the lateral fissure

Question 8

what are the deep branches of the MCA called and where do they supply blood to?

Answer 8

lenticulostriate arteries- body of the caudate and most of the putamen, most of the globus pallidus, the middle part (or genu) of the internal
capsule, and the anterior hypothalamus

Question 9

where do the anterior cerebral arteries supply blood to?

Answer 9

medial surface of frontal and parietal lobes
inferior surface of frontal lobe
lateral surface of frontal and parietal lobes

anterior caudate and putamen and the anterior limb of the
internal capsule

Question 10

where does the anterior choroidal artery travel to?

Answer 10

choroid plexus of the lateral ventricle

Question 11

where does the anterior choroid artery perfuse?

Answer 11

globus pallidus
putamen
tail of caudate nucleus
posterior limb of internal capsule
hippocampus

Question 12

how is the anterior choroidal artery vulnerable to increases in blood pressure and what happens if this occurs?

Answer 12

it is small in diameter but branches off of the large, high-pressure internal carotid artery
this can lead to bursting of the small arterial walls and hemorrhagic stroke.

Question 13

what is a watershed area?

Answer 13

the area where two perfusion territories come together

Question 14

what are watershed areas vulnerable to?

Answer 14

severe drops in systemic blood pressure
partial occlusion of a major blood vessel

Question 15

where do the vertebral arteries supply blood to?

Answer 15

portions of the caudal and rostral medulla