Circulation of the CNS

Question 1

How much of the CO is required by the CNS?

Answer 1

10-20%

Question 2

Describe auto-regulation?

Answer 2

Adequate perfusion of CNS is maintained despite changes in arterial pressure

Question 3

Which major arterial systems form the Circle of Willis?

Answer 3

Vertebro-basilar system

Internal carotid system

Question 4

How are the anastamoses formed in the Circle of Willis advantageous?

Answer 4

Blood can bypass blockage in any part of the circle

Question 5

Which arteries form the origin of the Circle of Willis?

Answer 5

Internal carotid artery

Vertebral artery

Question 6

How does the internal carotid artery enter the cranium?

Answer 6

Runs through carotid canal

Enters in middle cranial fossa, lateral to optic chiasm

Question 7

How does the vertebral artery enter the cranium?

Answer 7

Through transverse foramina and into foramen magnum

Question 8

Describe the major branches of the Circle of Willis?

Answer 8

Posterior cerebral artery

Middle cerebral artery

Anterior cerebral artery

Posterior communicating artery

Anterior communicating artery

Question 9

Describe the vascular distribution of the ACA?

Answer 9

Medial part of frontal and parietal lobes

Includes motor and sensory cortices for lower limb

Question 10

Describe the pathway of the ACA?

Answer 10

Originates from internal carotid

Projects medially through longitudinal fissure

Forms hook around front of corpus callosum

Question 11

Describe the pathway of the MCA?

Answer 11

Originates from internal carotid

Projects straight out through lateral fissure towards lateral aspect of cerebrum

Question 12

Describe the vascualr distribution of the MCA?

Answer 12

Lateral surface of brain (including parts of all four lobes and insula)

Includes motor and sensory cortices for most of body (except lower limb), parieto-occipital asscoiation areas, and language areas

Question 13

Describe the pathway of the PCA?

Answer 13

Originates from basilar artery

Projects laterally and posteriorly and heads towards occipital lobes

Question 14

Describe the vascular distribution of the PCA?

Answer 14

Medial and inferior surfaces of temporal and occipital lobes

Includes visual cortex

Question 15

List the small perforating branches of the Circle of Willis?

Answer 15

Lenticulostriate arteries

Pontine branches

Question 16

What do the small perforating branches of the Circle of Willis supply?

Answer 16

Deep structures where they come off the main arteries

Lenticulostriate arteries: basal ganglia and internal capsule

Pontine branches: ventral pons

Question 17

Describe the origins of the small perforating branches in the Circle of Willis?

Answer 17

Lenticulostriate arteries: branch off MCA

Pontine branches: come directly off basilar artery

Question 18

What are the other named arteries that arise from the Circle of Willis?

Answer 18

Opthalmic artery

Anterior choroidal artery

Question 19

What dies the opthalmic artery supply?

Answer 19

Eye

Top of nasal cavity

Frontal scalp

Question 20

What does the anterior choroidal artery supply?

Answer 20

Structures in deep lateral hemispheres:

Optic tract

Lateral ventricles

Hippocampus

Question 21

List the brainstem arteries that arise from the Circle of Willis?

Answer 21

Superior cerebellar artery

Anterior inferior cerebellar artery

Posterior inferior cerebellar artery

(Anterior spinal artery)

Question 22

Decribe the blood supply to the midbrain?

Answer 22

Most from PCA

Colliculi - superior cerebellar artery

Question 23

Describe the blood supply to the pons?

Answer 23

Pontine branches of basilar artery

Question 24

Describe the blood supply to the medulla?

Answer 24

3 arteries:

Anterior spinal artery: supplies anterior and middle

Veretebral artery: supplies area around where olives are, ventrolateral

Posterior inferior cerebellar artery: supplies posterolateral

Question 25

Which arteries supply the spinal cord?

Answer 25

Anterior spinal artery

Posterior spinal arteries