6. The blood supply to the brain

Question 1

what are the two sets of circulation to the brain?

Answer 1

anterior circulation and posterior circulation

Question 2

Which areas do the anterior and posterior circulation supply?

Answer 2

o The anterior circulation supplies most of the cerebral hemispheres
o The posterior circulation supplies the brainstem, cerebellum, some of the temporal lobe and the occipital lobe

Question 3

which two sources does the brain receive arterial blood from?

Answer 3

o The anterior circulation is fed by the internal carotid arteries
o The posterior circulation is fed by the vertebral arteries

Question 4

which two arteries are part of the anterior circulation?

Answer 4

o anterior cerebral artery

o posterior cerebral artery

Question 5

What are the branches of the internal carotid artery?

Answer 5

Ophthalmic artery, anterior cerebral artery, middle cerebral artery, posterior communicating artery, (anterior choroidal artery)

Question 6

What is the main contributor to the anterior circulation?

Answer 6

Middle cerebral artery

Question 7

what is the MCA a direct continuation of ?

Answer 7

internal carotid artery

Question 8

what do the cortical branches of the MCA supply?

Answer 8

Cortical branches emerge from the lateral fissure 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

Question 9

what do the deep branches of the MCA supply?

Answer 9

Deep branches (the lenticulostriate arteries) supply deep grey matter structures including the lentiform nucleus and caudate as well as the internal capsule

Question 10

describe the areas that the ACA supply

Answer 10

 The left and right anterior cerebral arteries anastomose in the midline via the anterior communicating artery
 The vessels loop over the corpus callosum and send branches to the adjacent cortex
 Cortical branches supply the medial aspect of the frontal and parietal lobes (not the occipital lobe)
 There are also branches to the corpus callosum itself

Question 11

in stroked involving the ACA, which part of the body is more affected and why?

Answer 11

Lower half of body as represented more medially on the hemisphere

Question 12

What connects the anterior cerebral arteries?

Answer 12

anterior communicating artery

Question 13

What connects the anterior and posterior circulations (MCA and PCA)?

Answer 13

Posterior communicating artery

Question 14

What communication do the anterior and posterior circulations form?

Answer 14

Circle of willis

Question 15

What sits at the centre of the circle of willis?

Answer 15

Pituitary gland, optic chiasm

Question 16

which two arteries are a main part of the posterior circulation?

Answer 16

o Basilar artery

o The vertebral arteries

Question 17

what forms the basilar artery?

Answer 17

Midline vessel formed from the confluence of the vertebral arteries

Question 18

what are 4 main branches of the basilar artery?

Answer 18

• Terminal bifurcation gives rise to the posterior cerebral artery
• Superior cerebellar artery\
• Pontine arteries
• Anterior inferior cerebellar artery

Question 19

what do the posterior cerebral arteries supply?

Answer 19

o Supplies occipital lobe, inferior temporal lobe and
thalamus (via thalamoperforator and thalamogeniculate branches)
o Also supplies midbrain en passant

Question 20

what branches form the PCA to connect it to the anterior circulation?

Answer 20

Posterior communicating arteries

Question 21

what do the Superior cerebellar artery supply?

Answer 21

the superior aspect of the cerebellum and midbrain en passant

Question 22

what do the pontine arteries supply?

Answer 22

The pons (including descending corticospinal fibres)

Question 23

what do the Anterior inferior cerebellar artery supply>

Answer 23

the antero- inferior aspect of the cerebellum and lateral pons en passant

Question 24

What can damage to the pontine arteries lead to?

Answer 24

Locked-in syndrome - patients are conscious and only able to move their eyes

Question 25

what are the two main branches of the vertebral arteries?

Answer 25

o Anterior spinal arteries | o Posterior inferior cerebellar arteries

Question 26

what do the anterior spinal arteries supply?

Answer 26

converge in the midline to supply the anterior 2/3 of the spinal cord

Question 27

what do the posterior inferior cerebellar arteries supply?

Answer 27

the postero-inferior aspect of the cerebellum en passant

Question 28

What is the supply to the cerebellum and where do these vessels originate?

Answer 28

From basilar artery: - Superior cerebellar arteries - Anterior inferior cerebellar arteries From vertebral arteries: - Posterior inferior cerebellar arteries

Question 29

Which vessel in the circle of willis is most commonly affected by aneurysms?

Answer 29

Anterior communicating artery - possible effects by compression on optic chiasm

Question 30

Where does the anterior spinal artery form

Answer 30

Unpaired artery formed from branches of the vertebral artery at the region of the medulla -

Question 31

What region of the brain does the anterior, middle and posterior cerebral artery supply?

Answer 31

- Anterior: anteromedial portion of the cerebrum - Middle: situated laterally, supplying the majority of the lateral part of the brain - Posterior: supply both the medial and lateral parts of the posterior cerebrum (including the lateral inferior temporal lobe)

Question 32

What are the main branches of the middle cerebral artery?

Answer 32

- lenticulostriate arteries - MCA superior division - MCA inferior division

Question 33

What do the lenticulostriate arteries supply?

Answer 33

basal ganglia and internal capsule

Question 34

what is the difference in symptoms If internal capsule or thalamus affected in stroke?

Answer 34

internal capsule - motor affected due to affect on descending corticospinal tracts thalamus - sensory

Question 35

What might occlusion of the PCA lead to?

Answer 35

Contralateral - visual impairment (pattern of supply of the PCA) - somatosensory impairment (due to reduced blood flow to thalamus from branches supplying it from the PCA) etc.

Question 36

What might occlusion of the ACA lead to?

Answer 36

Contralateral - Paralysis or weakness of the foot and leg on the opposite side, due to involvement of leg part of the motor cortex - Cortical sensory loss in the opposite foot and leg etc.

Question 37

What might occlusion of the MCA lead to?

Answer 37

Contralateral - Paralysis (-plegia) or weakness (-paresis) of the contralateral face and arm (faciobrachial) - Sensory loss of the contralateral face and arm. - Damage to the dominant hemisphere (usually the left hemisphere) results in aphasia i.e. Broca's area or Wernicke's

Question 38

which arteries supply the spinal cord and which areas/.

Answer 38

posterior spinal artery - supply dorsal horn and dorsal column anterior spinal artery - supply ventral horn of grey matter and cortiscospinal tract and spinothalamic tract

Question 39

What are the symptoms if ASA blockage?

Answer 39

bilateral loss of spinothalamic modalities below blockage and upper motor neurone signs due to interruption of CST