Blood Supply of the Brain

Question 1

Why is there more blood supply to the gray matter of the brain?

Answer 1

More cell bodies in the gray matter, hence more blood necessary

Question 2

Define Autoregulation (Control of Blood Flow)

Answer 2

Vasoconstriction in response to increased blood pressure

Question 3

Define Chemoreception (Control of Blood Flow)

Answer 3

Metabolites monitor carbon dioxide levels in the brain and increase/decrease flow respectively

Question 4

What are the two sources of blood flow to the brain and by what percentage does each supply it?

Answer 4

Internal Carotid Arteries - 80%

Vertebral Arteries - 20%

Question 5

What are the branches of the Internal Carotid Arteries?

Answer 5

Anterior Cerebral Artery
Anterior Communicating Artery
Middle Cerebral Artery
Opthalmic Artery
Anterior Choroidal Artery
Posterior Communicating Artery

Question 6

What does the anterior cerebral artery supply? Where are deficits seen with ischemia?

Answer 6

• Medial frontal, and parietal lobes, and the corpus callosum
• Contralateral motor and somatosensory deficits, greater in LE

Question 7

What is the function of the anterior communicating artery?

Answer 7

Joins right and left anterior cerebral arteries

Question 8

What does the middle cerebral Artery Supply? What deficits are seen with ischemia?

Answer 8

• Lateral Cerebral hemispheres (most pre/post central gyri)

- Major Motor and Somatosensory Deficits; Language deficits if in dominant hemisphere

Question 9

What does the Opthalmic artery supply? What deficits are seen with ischemia?

Answer 9

• Orbital Contents

- Vision Loss

Question 10

What does the Anterior Choroidal Artery Supply? What are the deficits that are seen with ischemia?

Answer 10

• supplies choroid plexus (lateral ventricles), optic tract, internal capsule, thalamus
• Contralateral motor and somatosensory deficits as well as vision problems

Question 11

What is the function of the Posterior communicating artery?

Answer 11

Connects MCA to posterior cerebral artery

Question 12

Where are the lenticulostriate and lateral striate arteries from and what do they supply?

Answer 12

• MCA
• Deep structures of the Telencephalon and Diencephalon
• These can be frequent areas of stroke because of disproportionate deficits due to thalamic connections

Question 13

What do the vertebral arteries supply?

Answer 13

• most of the brainstem, cerebellum, and parts of the diencephalon, occipital and temporal lobes, also the spinal cord

Question 14

What are the branches of the vertebral arteries?

Answer 14

• Posterior spinal arteries (paired)
• Anterior Spinal Artery (Unpaired)
• Posterior Inferior Cerebellar Artery (PICA)

Question 15

What do the posterior spinal arteries supply?

Answer 15

Posterior 1/3 of that half of spinal cord

Question 16

What does the anterior spinal artery supply?

Answer 16

Anterior 2/3 of spinal cord

Question 17

What does PICA supply?

Answer 17

Inferior cerebellar surface, 4th ventricle choroid plexus, lateral medulla

Question 18

What are the branches of the Basilar Artery?

Answer 18

• Anterior Inferior Cerebellar Artery (AICA)
• Superior Cerebellar Artery
• Pontine Arteries
• Labyrinthine Artery/internal auditory artery
• Posterior Cerebral Artery

Question 19

What does AICA supply?

Answer 19

Anteroinferior Cerebellum and Caudal Pons

Question 20

What does the superior Cerebellar artery supply?

Answer 20

Superoanterior cerebellum, caudal midbrain, rostral pons

Question 21

What do the pontine arteries supply?

Answer 21

Remainder of pons

Question 22

What does the Labyrinthine/internal auditory artery supply? What deficits are seen with ischemia?

Answer 22

• Inner ear

- Results in vertigo and ipsilateral deafness

Question 23

What does the posterior cerebral artery supply? What deficits are seen with ischemia?

Answer 23

• inferomedial occipital/temporal lobes and posterior choroid plexus of 3rd ventricle
• visual field losses

Question 24

What are the causes of Ischemic Strokes?

Answer 24

• Altered blood pressure
• Arterial Disease
• Blockage

Question 25

What are some causes of hemorrhagic stroke?

Answer 25

• Spontaneous rupture of small blood vessels

- Causes ischemia distal to the rupture

Question 26

What is the difference between a Transient Ischemic Attack (TIA) and a Stroke (CVA)?

Answer 26

• TIAs - last 24 hrs or less, usually little or no neurologic defects
• Strokes - Greater than 24 hrs

Question 27

What are the results of spinal cord ischemias?

Answer 27

Sensory or motor deficits in extremities distal to lesion site

Question 28

What is an aneurysm and what two ways can it cause deficits?

Answer 28

• Balloon like swelling of the arterial walls
  1. Compresses structures as it grows
  2. Rupture could result in massive hemorrhaging causing a subarachnoid hemorrhage

Question 29

What are arteriovenous malformations and what can they cause?

Answer 29

• congenital defects where large anastomoses exist between arteries and veins
  
  • can steal blood from adjacent arteries
  • can cause hemorrhage

Question 30

What is the role of emissary veins in the brain?

Answer 30

• Connect extracranial veins with dural sinuses, they may spread infection into the cranial cavity

Question 31

Where do the superficial veins of the brain reside?

Answer 31

Surface of the cerebral hemispheres, variable locations

Question 32

What are the 2 groups of superficial veins?

Answer 32

Superior Group - empties into superior sagittal sinus

Inferior Group - empties into transverse and cavernous sinus

Question 33

What are the roles of the deep cerebral veins?

Answer 33

• Drain internal structures
• More consistant configuration
• Empty into straight sinus

Question 34

What are the 2 deep cerebral veins?

Answer 34

• Internal cerebral vein - forms next to the interventricular foramen bends posteriorly
• Great Cerebral Vein (Great Vein of Galen) - formed by fusion of 2 internal cerebral veins; joins with inferior sagittal sinus to form straight sinus