Circulation of the CNS Flashcards
What forms the circle of Willis?
Vertebro-basilar system and internal carotid system.
These anastomose to form a circle which allows blood to reach the brain if one is damaged.
What is the origin of the circle of Willis?
Internal carotid artery in the carotid canal and vertebral artery travelling in the transverse foramina and foramen magnum.
What does the internal carotid artery travel in?
Carotid canal
What does the vertebral artery travel in?
Transverse foramina and foramen magnum
What are the main branches of the circle of Willis?
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
What is the point of anastomoses between the anterior cerebral arteries?
Anterior communicating artery
What does the anterior cerebral artery supply?
Medial part of frontal and parietal lobes.
Which functional territories does the anterior cerebral artery supply?
Motor and sensory cortices for lower limb
What are the 2 branches off the anterior cerebral artery?
Pericallosal branch
Callosomarginal branch
What does the middle cerebral artery supply?
Lateral surface of brain, including parts of frontal, parietal, temporal and occipital lobes and insula.
Which functional territories does the middle cerebral artery supply?
Motor and sensory cortices for most of the body (except lower limb)
Parieto-occipital association areas
Language areas (on dominant side)
What does the posterior cerebral artery supply?
Medial and inferior surfaces of temporal and occipital lobes
Which functional territories does the posterior cerebral artery supply?
Visual cortex
What do the small perforating branches off the circle of Willis supply?
Deep structures where they come off main arteries
What do perforating branches off the anterior circle of Willis supply?
Optic chiasm
Anterior hypothalamus
What do the lenticulostriate arteries supply?
Basal ganglia
Internal capsule
What do small perforating branches off the posterior circle of Willis supply?
Ventral midbrain
Posterior hypothalamus
Thalamus
What do the pontine branches supply?
Ventral pons
Where does the opthalmic artery arise from?
Internal carotid artery just before the circle of Willis
What does the ophthalmic artery supply?
Passes into orbit:
Eye (including retina)
Top of nasal cavity
Frontal scalp
Where does the anterior choroidal artery arise from?
Internal carotid artery just before the circle of Willis (moving posteriorly)
What does the anterior choroidal artery supply?
Structures in deep lateral hemispheres:
Optical tract
Lateral ventricles
Hippocampus
Which arteries comprise the vertebro-basilar system brainstem arteries?
Posterior cerebral artery
Superior cerebellar artery
Anterior inferior cerebellar artery
Posterior inferior cerebellar artery
Vertebral artery
Anterior spinal artery
What do the superior cerebellar arteries supply?
Superior cerebellum
What does the posterior inferior cerebellar artery supply?
Posterior and inferior cerebellum
What does the anterior inferior cerebellar artery supply?
Anterior inferior cerebellum
What gives rise to the basilar artery?
Anterior spinal artery and vertebral artery
What supplies the midbrain?
Posterior cerebral artery
Superior cerebellar artery
Which arteries supply the pons?
Basilar branches:
paramedian
short and long circumferential arteries
What supplies the medulla?
Posterior inferior cerebellar artery
Vertebral artery
Anterior spinal artery
What is medial medullary syndrome?
Cerebrovascular accident associated with anterior spinal artery affecting the medial medulla:
Pyramids (corticospinal tract) - contralateral hemiparesis (UPM)
Medial lemniscus - contralateral somatosensory hemideficit
Hypoglossal nucleus - ipsilateral paralysis and atrophy of tongue (LMN)
Which arteries supply the spine?
Anterior and posterior spinal arteries joined by circumferential arteries
What gives rise to anterior and posterior spinal arteries?
Segmental branches of aorta, e.g. intercostal or lumbar arteries
How is blood drained from the brain?
Cerebral veins run in sub-arachnoid space and drain into a series of sinuses
Each venous sinus is a space between two layers of dura
What can cross the blood-brain barrier?
Gases and some lipid soluble substances can diffuse across these barriers, and glucose and important amino acids are actively transported across the barriers
