4.2 Blood Supply to the Brain

Question 1

Where does the brain recieve arterial blood from?

Answer 1

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

Question 2

What are the two main branches of the anterior circulation?

Answer 2

Middle cerebral artery
Anterior cerebral artery

Question 3

Where do the middle and anterior cerebral arteries originate from?

Answer 3

Middle- direct continuation of the internal carotid

Anterior- branch of the internal carotid

Question 4

What are the two divisions of the middle cerebral artery?

Answer 4

Cortical branches- supplying cortex and white matter

Deep branches (lenticulostriate)- supplying the deep grey matter structures

Question 5

Describe the blood supply of the middle cerebral artery

Answer 5

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

Question 6

What part of the middle cerebral artery is most susceptible to stroke?

Answer 6

Lenticulostriates

Question 7

What is the structure of the anterior cerebral artery?

Answer 7

Has left and right branches which anastomose in the middle via the anterior communicating artery

Question 8

What is the course of the anterior cerebral artery?

Answer 8

Loops over the corpus callosum and sends branches to the adjacent cortex

Question 9

What can happen to the corpus callosum in a stroke which affected the anterior cerebral artery?

Answer 9

Loss of corpus callosum causing the hemispheres to become disconnected

Question 10

What does the anterior cerebral artery supply?

Answer 10

Cortical branches
-Medial aspect of the frontal and parietal lobes
-Branches to corpus callosum

Question 11

What can happen in a calcarine herniation?

Answer 11

Calcarine sulcus can be pushed underneath the falx cerebri

This causes compression of the anterior cerebral artery, leading to a stroke

Question 12

When the vertebral arteries coalesce together what does it form?

Answer 12

Basilar artery

Question 13

What does the terminal bifurcation of the basilar artery give rise to?

Answer 13

Posterior cerebral artery

Question 14

What does the posterior cerebral artery supply?

Answer 14

Supplies occipital lobe
Inferior temporal lobe
Thalamus (via thalamoperforator and thalmogeniculate branches)

Mid brain (in passing)

Question 15

How does the posterior circulation connect to the anterior circulation?

Answer 15

Connects via posterior communicating arteries

Question 16

What are the major branches of the basilar artery?

Answer 16

Posterior cerebral artery
Superior cerebellar arteries
Pontine arteries
Anterior inferior cerebellar arteries

Question 17

What does the superior cerebellar artery supply?

Answer 17

Superior cerebellum and mid brain in passing

Question 18

What do the pontine arteries supply?

Answer 18

Pons, including descending corticospinal fibres

Question 19

What does the anterior inferior cerebellar artery supply?

Answer 19

Anterio-inferior cerebellum and lateral pons in passing

Question 20

What two important branches does the vertebral artery give rise to?

Answer 20

Anterior spinal artery
Posterior inferior cerebellar artery

Question 21

How does the anterior spinal artery form and what does it supply?

Answer 21

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

Question 22

What do the posterior inferior cerebellar arteries supply?

Answer 22

Postero-inferior aspect of the cerebellum in passing

Question 23

What happens in an anterior spinal artery occlusion?

Answer 23

Loss of spinothalamic tract modalities bilaterally below obstruction

Question 24

What happens in a posterior spinal artery occlusion?

Answer 24

Loss of dorsal column modalities bilaterally below occlusion

Question 25

What happens in a lenticulostriate artery stroke?

Answer 25

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

Question 26

What do lacunar infarcts lead to?

Answer 26

Small lacunes, basically, small holes where tiny strokes have occurred

Question 27

What happens in strokes involving the anterior cerebral artery?

Answer 27

Anterior cerebral artery supplies midline structures, therefore the primary motor cortex would be affected medially, which is the position of the legs

Question 28

What general rule applies to blood supply in the brain?

Answer 28

If an artery runs over a part of the brain, it provides some supply to it

Question 29

What part of the middle cerebral artery is most susceptible to stroke?

Answer 29

Lenticulostriates

Question 30

Draw out the circle of willis

Answer 30