Cerebral blood supply

Question 1

Which part of the brain does the internal carotid arteries supply

Answer 1

Anterior 2/3 of the cerebral hemispheres and the basal ganglia

Question 2

Where is the circle of Willis found?

Answer 2

At the base of the brain

Question 3

What is the circle of willis?

Answer 3

An anastomotic ring fed by 3 arteries which supply the brain with blood

Question 4

Which arteries form the basilar artery

Answer 4

Right and left vertebral artery and the anterior spinal artery

Question 5

Describe the arrangement of the circle of Willis

Answer 5

Basilar artery - posterior - formed by joining of vertebral arteries - supply brainstem
Internal carotid artery - Anteriorly

Anterior and middle cerebral arteries are branches of the internal carotid artery
The basilar artery divides into the two posterior cerebral arteries

Question 6

What is the adaptational benefit of the circle of Willis arrangement

Answer 6

May compensate for effects of occlusion of a feeder vessel by allowing supply from unaffected vessels

Question 7

What does the anterior cerebral artery supply?

Answer 7

Frontal and medial part of the cerebrum

Question 8

What does occlusion of the anterior cerebral artery cause

Answer 8

Weak, numb contralateral leg +/- similar if milder arm symptoms
Face is spared
Bilateral infarction very rare cause of paraplegia or an even rarer cause of akinetic mutism

Question 9

What does the middle cerebral artery supply?

Answer 9

Lateral part of each hemisphere

Question 10

What does occlusion of the middle cerebral artery cause

Answer 10

Contralateral hemiparesis, hemisensory loss especially of face and arm, contralateral homonymous hemianopia due to involvement of the optic radiation
Cognitive change including dysphagia with dominant hemisphere lesions
Visuospatial disturbance with non dominant lesions

Question 11

What does the posterior cerebral artery supply

Answer 11

Occipital lobe

Question 12

What does posterior cerebral artery occlusion cause

Answer 12

Contralateral homonymous hemianopia often with macula sparing

Question 13

What does the vertebrobasilar circulation supply

Answer 13

Cerebellum
Brainstem
Occipital lobe

Question 14

What does occlusion of the vertebrobasilar circulation cause

Answer 14

Hemianopia
Cortical blindness 
Vertigo
Nystagmus
Ataxia
Dysarthria
Dysphasia
Hemi/quadriplegia
Uni/bilateral sensory syndromes
Hiccups
Coma

Question 15

List some syndromes caused by lesions of the brainstem

Answer 15

Lateral medullary syndrome

Locked in syndrome

Question 16

Describe lateral medullary syndrome

Answer 16

Occlusion of one vertebral artery or the posterior inferior cerebellar artery causes infarction of the lateral medulla and the inferior cerebellar artery
Vertigo, vomiting, dysphagia, nystagmus, ipsilateral ataxia, soft palate paralysis, ipsilateral Horner’s syndrome and a crossed pattern sensory loss

Question 17

Describe locked in syndrome

Answer 17

Damage to the ventral pons due to pontine artery occlusion
Patients are unable to move but retain full cognition and awareness, communicating by blinking, electronic boards or special computers

Question 18

Describe subclavian steal syndrome

Answer 18

Subclavian artery stenosis proximal to the origin of the vertebral artery may cause blood to be stolen by retrograde flow down this vertebral artery into the arm, causing brainstem ischaemia typically after use of the arm
Suspect if the BP in each arm differs by >20mmHg