4.2 Blood Supply to the Brain Flashcards
Where does the brain recieve arterial blood from?
Anterior circulation- from internal carotids, supplies most of the cerebral hemispheres
Posterior circulation- from vertebral arteries,
supplies brainstem, cerebellum, some of the temporal and occipital lobe
What are the two main branches of the anterior circulation?
Middle cerebral artery
Anterior cerebral artery
Where do the middle and anterior cerebral arteries originate from?
Middle- direct continuation of the internal carotid
Anterior- branch of the internal carotid
What are the two divisions of the middle cerebral artery?
Cortical branches- supplying cortex and white matter
Deep branches (lenticulostriate)- supplying the deep grey matter structures
Describe the blood supply of the middle cerebral artery
Cortical branches emerge from the lateral fissure (sylvian) to supply the lateral aspect of the cerebral hemisphere (cortex and underlying white matter)
Including lateral parts of the frontal and parietal lobes as well as the superior temporal lobe
Deep branches (lenticulostriate arteres)- supply deep grey matter structures including the lentiform nucleus and caudate as well as the internal capsule
What part of the middle cerebral artery is most susceptible to stroke?
Lenticulostriates
What is the structure of the anterior cerebral artery?
Has left and right branches which anastomose in the middle via the anterior communicating artery
What is the course of the anterior cerebral artery?
Loops over the corpus callosum and sends branches to the adjacent cortex
What can happen to the corpus callosum in a stroke which affected the anterior cerebral artery?
Loss of corpus callosum causing the hemispheres to become disconnected
What does the anterior cerebral artery supply?
Cortical branches
-Medial aspect of the frontal and parietal lobes
-Branches to corpus callosum
What can happen in a calcarine herniation?
Calcarine sulcus can be pushed underneath the falx cerebri
This causes compression of the anterior cerebral artery, leading to a stroke
When the vertebral arteries coalesce together what does it form?
Basilar artery
What does the terminal bifurcation of the basilar artery give rise to?
Posterior cerebral artery
What does the posterior cerebral artery supply?
Supplies occipital lobe
Inferior temporal lobe
Thalamus (via thalamoperforator and thalmogeniculate branches)
Mid brain (in passing)
How does the posterior circulation connect to the anterior circulation?
Connects via posterior communicating arteries
What are the major branches of the basilar artery?
Posterior cerebral artery
Superior cerebellar arteries
Pontine arteries
Anterior inferior cerebellar arteries
What does the superior cerebellar artery supply?
Superior cerebellum and mid brain in passing
What do the pontine arteries supply?
Pons, including descending corticospinal fibres
What does the anterior inferior cerebellar artery supply?
Anterio-inferior cerebellum and lateral pons in passing
What two important branches does the vertebral artery give rise to?
Anterior spinal artery
Posterior inferior cerebellar artery
How does the anterior spinal artery form and what does it supply?
Branch from each of the left and right vertebral arteries and segmental arteries (from aorta) anastamose forming the artery
Supplies the anterior 2/3 of the cord
What do the posterior inferior cerebellar arteries supply?
Postero-inferior aspect of the cerebellum in passing
What happens in an anterior spinal artery occlusion?
Loss of spinothalamic tract modalities bilaterally below obstruction
What happens in a posterior spinal artery occlusion?
Loss of dorsal column modalities bilaterally below occlusion
What happens in a lenticulostriate artery stroke?
Most commonly affected in a stroke
Lacunar stroke/infarct
Supplies a large area therefore stroke symptoms can differ greatly
Basal ganglia affected, parkinsonian effects
Internal capsule- motor stroke as it contains descending motor neurones
What do lacunar infarcts lead to?
Small lacunes, basically, small holes where tiny strokes have occurred
What happens in strokes involving the anterior cerebral artery?
Anterior cerebral artery supplies midline structures, therefore the primary motor cortex would be affected medially, which is the position of the legs
What general rule applies to blood supply in the brain?
If an artery runs over a part of the brain, it provides some supply to it
What part of the middle cerebral artery is most susceptible to stroke?
Lenticulostriates
Draw out the circle of willis
