Neuro - Anat & Phys (Vasculature & Cerebral Perfusion)

Question 1

What is the Circle of Willis?

Answer 1

System of anastomoses between anterior and posterior blood supplies to brain

Question 2

What 3 major arteries are included in the anterior circulation of the brain?

Answer 2

(1) ACA - Anterior cerebral (2) ICA - Internal carotid (3) MCA - Middle cerebral

Question 3

What 3 major arteries are included in the posterior circulation of the brain?

Answer 3

(1) PCA - Posterior cerebral (2) BA - Basilar (3) VA - Vertebral

Question 4

Draw an inferior view of the brain, shading in anterior versus posterior circulation territories.

Answer 4

See p. 458 in First Aid 2014 for visual at far left

Question 5

Draw the Circle of Willis and its related circulation, labeling the following arteries: (1) Anterior communicating (ACom) (2) Anterior cerebral (ACA) (3) Anterior inferior cerebellar (AICA) (4) Anterior spinal (ASA) (5) Anterior choroidal (6) Basilar (BA) (7) Internal carotid (ICA) (8) Middle cerebral (MCA) (9) Letinculo-striate (10) Posterior communicating (PCom) (11) Posterior cerebral (PCA) (12) Posterior inferior cerebellar (PICA) (13) Pontine (14) Superior cerebellar (SCA) (15) Vertebral (VA). Also include the optic chiasm.

Answer 5

See p. 458 in First Aid 2014 for middle visual

Question 6

Draw an oblique-lateral view of the vessels leading into and within the brain, labeling the following arteries: (1) Aorta (2) ACA (3) BA (4) CCA (5) Brachio-cephalic (6) ICA (7) MCA (8) PCA (9) PCom (10) Subclavian (11) ECA (12) VA.

Answer 6

See p. 458 in First Aid 2014 for visual at far right

Question 7

Draw lateral, medial, and inferior views of the brain, labeling and shading the cortical distribution of circulation by the following arteries: (1) Anterior cerebral artery (2) Middle cerebral artery (3) Posterior cerebral artery.

Answer 7

See p. 459 in First Aid 2014 for visual at top

Question 8

What part of the cortex does the anterior cerebral artery supply?

Answer 8

Supplies anteromedial surface

Question 9

What part of the cortex does the middle cerebral artery supply?

Answer 9

Supplies lateral surface

Question 10

What part of the cortex does the posterior cerebral artery supply?

Answer 10

Supplies posterior and inferior surfaces

Question 11

What are watershed zones? What symptoms/effects can they causes, and why?

Answer 11

Between anterior cerebral/middle cerebral, posterior cerebral/middle cerebral arteries. Damage (results) in severe hypotension –> upper leg/upper arm weaknesses, defects in higher-order visual processing

Question 12

On what mechanism does brain perfusion rely?

Answer 12

Brain perfusion relies on tight autoregulation

Question 13

What primarily drives brain perfusion? What else can have an effect, and in what context?

Answer 13

Cerebral perfusion is primarily driven by pCO2 (PO2 also modulates perfusion in severe hypoxia)

Question 14

How does therapeutic hyperventilation work as it relates to cerebral perfusion? In what setting(s) is it used?

Answer 14

Therapeutic hyperventilation (decreasing pCO2) helps to decrease intracranial pressure in cases of acute cerebral edema (stroke, trauma) via decreased cerebral perfusion by vasoconstriction.

Question 15

At what point is cerebral perfusion pressure no longer proportional to pCO2? Draw and label a graph depicting this.

Answer 15

Cerebral perfusion pressure proportional to pCO2 until pCO2 > 90 mmHg; See p. 459 in First Aid 2014 for graph on bottom right

Question 16

At what point does hypoxemia increase cerebral perfusion pressure? Draw and label a graph depicting this.

Answer 16

Hypoxemia increases cerebral perfusion pressure only when pO2 < 50 mmHg