Lecture 21: Cerebral Blood Supply

Question 1

What artery supplies the anterior 2/3 of the cerebral hemispheres?

Answer 1

Internal carotid artery

Question 2

Major regions supplied by carotid circulation

Answer 2

1. Optic nerves and retina
2. Cortex and deep white matter of frontal/parietal; lateral parts of temporal/occipital
3. Corpus callosum except posterior region
4. Most of basal ganglia and internal capsule

Question 3

Know and label Circle of Willis circulation (picture)

Answer 3

Question 4

First branch of internal carotid artery

Answer 4

Ophthalmic artery which supplies eye and structures around orbit

Question 5

Anterior Cerebral Artery

Answer 5

• Comes off the internal carotid at nearly right angle
• Sends branches to basal ganglia
• Runs up and around the corpus callosum
• Supplies septal area
• Supplies Motor cortex of leg/foot and urinary bladder
• Motor planning areas in medial frontal lobe
• Primary somatosensory cortex for leg/foot
• Supplies corpus callosum except for posterior part

Question 6

Middle Cerebral Artery

Answer 6

• Runs in sylvian fissure laterally under frontal lobe
• Gives off 6-12 lenticulostriate arteries which are vulnerable to high blood pressure
• Supplies lateral surface of brain and insula

Question 7

Key areas that the superior branches of MCA supply

Answer 7

1. Primary motor cortex for face and arm
2. Broca’s area for language
3. Frontal eye fields
4. Primary somatosensory cortex for face and arm
5. Parts of lateral frontal and parietal lobes

Question 8

Key areas that the posterior branches of the MCA supply

Answer 8

1. Wernicke’s area for language comprehension
2. Lateral parietal and temporal lobe for spatial and emotion recognition
3. Lateral primary somatosensory cortex
4. Optic radiations from visual thalamus to cortex

Question 9

What does the posterior cerebral artery arise from?

Answer 9

Basilar artery

Question 10

Posterior Cerebral Artery

Answer 10

• Sends branches to midbrain, hypothalamus, and thalamus
• Cortical branches go to posterior medial parietal lobe
• Inferior and medial part of temporal lobe
• Medial and inferior surfaces of the occipital lobe

Question 11

Key areas that the penetrating branches of PCA supplies

Answer 11

• Diencephalon- thalamus, subthalamic nuc., and hypothalamus
• Midbrain
  
  • Cerebral peduncle
  • Third nerve and nucleus
  • Red nucleus and connections
  • Superior cerebellar peduncle
  • Reticular formation

Question 12

Key areas that the cortical branches of the PCA supplies

Answer 12

• Posterior branches of parietal and occipital lobe
  
  • Optic radiations and striate cortex
  • Splenium of corpus callosum- visual info to language areas
• Medial temporal lobe
  
  • Posterior hippocampal formation and fornix- new declarative memories

Question 13

How is blood pressure regulated in the brain?

Answer 13

Autoregulation- vessels constrict or dilate locally in response to blood pressure

Question 14

What happens to the vessels in an active area of brain tissue?

Answer 14

More CO₂leads vessels to dilate and increase flow

Question 15

Terminal arteries in brain

Answer 15

No anastomotic connections; sudden occlusion leads to problems

Question 16

Major anastomoses in brain

Answer 16

1. External and internal carotid via ophthalmic artery branches
2. Circle of Willis
3. Cervical arteries and extracranial vertebral or external carotid vessels
4. Small cortical branches of the ACA, MCA, and PCA

Question 17

Where do saccular aneurysms usually form?

Answer 17

Where vessels branch