Circulation of the CNS Flashcards
How much of the CO is required by the CNS?
10-20%
Describe auto-regulation?
Adequate perfusion of CNS is maintained despite changes in arterial pressure
Which major arterial systems form the Circle of Willis?
Vertebro-basilar system
Internal carotid system
How are the anastamoses formed in the Circle of Willis advantageous?
Blood can bypass blockage in any part of the circle
Which arteries form the origin of the Circle of Willis?
Internal carotid artery
Vertebral artery
How does the internal carotid artery enter the cranium?
Runs through carotid canal
Enters in middle cranial fossa, lateral to optic chiasm
How does the vertebral artery enter the cranium?
Through transverse foramina and into foramen magnum
Describe the major branches of the Circle of Willis?
Posterior cerebral artery
Middle cerebral artery
Anterior cerebral artery
Posterior communicating artery
Anterior communicating artery
Describe the vascular distribution of the ACA?
Medial part of frontal and parietal lobes
Includes motor and sensory cortices for lower limb
Describe the pathway of the ACA?
Originates from internal carotid
Projects medially through longitudinal fissure
Forms hook around front of corpus callosum
Describe the pathway of the MCA?
Originates from internal carotid
Projects straight out through lateral fissure towards lateral aspect of cerebrum
Describe the vascualr distribution of the MCA?
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
Describe the pathway of the PCA?
Originates from basilar artery
Projects laterally and posteriorly and heads towards occipital lobes
Describe the vascular distribution of the PCA?
Medial and inferior surfaces of temporal and occipital lobes
Includes visual cortex
List the small perforating branches of the Circle of Willis?
Lenticulostriate arteries
Pontine branches
What do the small perforating branches of the Circle of Willis supply?
Deep structures where they come off the main arteries
Lenticulostriate arteries: basal ganglia and internal capsule
Pontine branches: ventral pons
Describe the origins of the small perforating branches in the Circle of Willis?
Lenticulostriate arteries: branch off MCA
Pontine branches: come directly off basilar artery
What are the other named arteries that arise from the Circle of Willis?
Opthalmic artery
Anterior choroidal artery
What dies the opthalmic artery supply?
Eye
Top of nasal cavity
Frontal scalp
What does the anterior choroidal artery supply?
Structures in deep lateral hemispheres:
Optic tract
Lateral ventricles
Hippocampus
List the brainstem arteries that arise from the Circle of Willis?
Superior cerebellar artery
Anterior inferior cerebellar artery
Posterior inferior cerebellar artery
(Anterior spinal artery)
Decribe the blood supply to the midbrain?
Most from PCA
Colliculi - superior cerebellar artery
Describe the blood supply to the pons?
Pontine branches of basilar artery
Describe the blood supply to the medulla?
3 arteries:
Anterior spinal artery: supplies anterior and middle
Veretebral artery: supplies area around where olives are, ventrolateral
Posterior inferior cerebellar artery: supplies posterolateral
Which arteries supply the spinal cord?
Anterior spinal artery
Posterior spinal arteries
