Blood Supply to The Brain

Question 1

Outline and compare the 2 sources of arterial blood to the brain

Answer 1

Anterior circulation;

• Fed by Internal Carotid arteries
• Supplies most of cerebral hemispheres

Posterior circulation;

• Fed by Vertebral arteries
• Supplies Brainstem, Cerebellum, Occipital lobe and some of the Temporal lobe

Question 2

Name a structure that the circle of Willis surrounds

Answer 2

Optic Chiasm

Question 3

Outline arterial circulation of the Circle of Willis up to the point where the Basilar Artery is formed

Answer 3

Vertebral arteries give off 2 branches;

1. Laterally-> Posterior Inferior Cerebellar Artery
2. Medial branches fuse-> Anterior Spinal Artery

Then the arteries fuse-> Basilar artery

Question 4

Outline arterial circulation of the Circle of Willis up to the point between the Basilar artery up to where the Posterior Communicating arteries branch off

Answer 4

Basilar artery gives off 4 sets of branches

• Laterally-> Anterior Inferior Cerebellar Artery
• Laterally-> Pontine arteries
• Laterally-> Superior Cerebellar Artery
• BA bifurcates-> Posterior Cerebral Artery

Posterior Cerebral artery gives off branches-> Posterior Communicating Arteries

Question 5

Describe the anterior circulation of the Circle of Willis, including its connection to the Posterior Circulation

Answer 5

• Internal carotid gives off 2 branches: Anterior and Middle Cerebral Arteries
• MCA connected to PCA by Posterior Communicating Arteries
• ACAs connected to each other by Anterior Communicating Artery

Question 6

Describe the circulation of the Middle Cerebral Artery

Answer 6

Cortical Branches;
- Emerge from Lateral Fissure to supply lateral cerebral hemisphere, then branch Superiorly and Inferiorly

Deep Branches/ Lenticulostriate arteries;

• Branch off MCA before the Cortical branches
• Supply deep grey matter structures

Question 7

Which lobe/ lobe parts are supplied by the Cortical branches of the middle cerebral artery?

Answer 7

• Lateral parts of Frontal
• Lateral parts of Parietal
• Superior Temporal

Question 8

Name 3 deep grey matter structures supplied by the Deep branches of the MCA/ Lenticulostriate arteries

(The deep branches are commonly occluded in strokes)

Answer 8

• Lentiform nucleus
• Caudate
• Internal capsule

Question 9

Describe the circulation of the Anterior Cerebral Artery

Answer 9

• Loops over the Corpus Callosum and gives off ascending Cortical branches
• These branches supply the Medial surface of the Frontal and Parietal lobes (Hence lower body affected usually in ACA strokes)
• The ACA also gives off branches which supply the Corpus Callosum, as it loops around the CC

Question 10

Describe a Subfalcine Herniation and its effect on the ACA

Most common form of intracranial herniation

Answer 10

Cingulate gyrus is pushed under the Falx Cerebri, leading to compression of the ACA as it loops around the Corpus Callosum.

This can lead to a stroke

Question 11

Describe the circulation of the Posterior Cerebral arteries

Answer 11

Run along inferior aspect of posterior hemisphere to supply;

• Occipital lobe
• Inferior Temporal lobe
• Thalamus
• Midbrain

Question 12

Which arteries are affected in a Lacunar stroke/ Infarct

Answer 12

Lenticulostriate arteries (Deep branches of MCA)

Question 13

What is a Lacune/ Lacunar Infarct in the brain?

Answer 13

Patchy areas of brain caused by stroke

Region affected influences symptoms

Question 14

What does the Superior Cerebellar Artery supply?

Answer 14

• Superior aspect of Cerebellum

- Midbrain

Question 15

What do the Pontine arteries supply?

Answer 15

The Pons (Including descending corticospinal fibres)

Question 16

What does the Anterior Inferior Cerebellar Artery supply?

Answer 16

• Anteroinferior aspect of cerebellum

- Lateral aspect of Pons

Question 17

Occlusion of the Pontine/ Basilar arteries can lead to destruction of the Corticospinal Tract, leading to ‘Locked in’ syndrome

Describe this

Answer 17

Cant move limbs, only eyes

Question 18

What does the Posterior Inferior Cerebellar Artery supply?

Answer 18

• Posteroinferior aspect of Cerebellum

- Lateral aspect of medulla

Question 19

What do the Anterior Spinal arteries supply?

Answer 19

Anterior 2/3 of spinal cord, after converging in midline

Posterior spinal arteries supplies posterior 1/3

Question 20

Which artery joins the Anterior Spinal Artery in the lower 1/3 of the spinal cord, and is at risk in aneurysm repair?

Answer 20

Artery of Adamkiewicz