Blood Supply and Cerebral Blood Flow

Question 1

Which veins have little supporting structure and are vulnerable to injury forming a subdural hematoma?

Answer 1

Superior cerebral veins. These cross the subdural space (from arachnoid to superior sagittal sinus)

Question 2

Which veins connect the dural sinuses (superior sagittal sinus or cavernous sinus) with extracranial veins of the scalp and face?

Answer 2

Emissary veins

Question 3

Why do emissary veins have a greater potential for spreading infection (e.g. meningitis) from outside the cranium to venous sinesus within?

Answer 3

Emissary veins have no valves and allow for free communication between these venous systems

Question 4

Veins of which features roughly follow the arterial system?

Answer 4

Veins of the brainstem, cerebellum and spinal cord

Question 5

What is a potential consequence of the absence of valves in spinal cord veins?

Answer 5

Since there are no valves, flow is easliy reversed. This provides a means through which metastases from the pelvis, kidney, or lung may spread to vertebral bodies or to the CNS.

Question 6

The brain, brainstem, and cerebellum are supplied by which two major arteries?

Answer 6

The internal carotid arteries and vertebral arteries.

Occlusion of these arteries or smaller branches causes damage to areas of the CNS supplied by these vessels.

Question 7

Approximately what percentage of blood to the cerebrum is supplied by vertebral arteries?

Answer 7

15%. These vessels enter the foramen magnum, penetrate the dura mater and arachnoid; then enter the subarachnoid space.

Question 8

Which arteries supply most of the brainstem through their branches?

Answer 8

vertebral arteries

Question 9

The Anterior spinal artery (a single, unpaired artery) supplies blood to what part of the spinal cord?

Answer 9

It supplies blood to the anterior 2/3 of the spinal cord (running in a rostral to caudal direction in the ventral medial fissure of the spinal cord)

Question 10

Which arteries branch off the vertebral artery; descend caudally as separate trunks and serve the posterior 1/3 of spinal cord?

Answer 10

The Posterior spinal arteries (paired)

Question 11

Which arteries branch off the vertebral arteries before joining to form the basilar artery and provide blood to the posterior part of cerebellar hemispheres, vermis, and lateral and posterior medulla?

Answer 11

Posterior inferior cerebellar arteries

Question 12

What are the four main branches of the basilar artery?

Answer 12

a. Anterior inferior cerebellar artery
b. Pontine arteries
c. Superior cerebellar arteries
d. Posterior cerebral arteries

Question 13

The anterior inferior cerebellar artery (branch of the basilar artery) supplies blood mainly to which structures?

Answer 13

inferior cerebellum and deep cerebellar nuclei and part of the pons

Question 14

The pontine arteries (branches of the basilar artery) supply blood mainly to which structures?

Answer 14

They penetrate the pons and supply this region of brainstem and all nuclei located there, including the reticular formation.

Question 15

The superior cerebellar arteries (branches of the basilar artery) supply blood mainly to which structures?

Answer 15

They supply the dorsum of the cerebellum and deeper structures, midbrain, pons and superior cerebellar peduncle

Question 16

The posterior cerebral arteries (branches of the basilar artery) supply blood mainly to which structures?

Answer 16

They supply the inferior surface of temporal lobe and medial occipital lobe to parieto-occipital fissure, thalamus, midbrain, internal capsule, cerebral peduncle, substantia nigra, and red nucleus.

Question 17

What do the Posterior communicating arteries connect?

Answer 17

They connect the internal carotid system to the vertebral-basilar system; (and are part of the circle of Willis)

Question 18

Which blood vessels are reponsible for supplying about 85% of the blood to the Cerebrum?

Answer 18

Internal carotid arteries

Question 19

The internal carotid arteries branch to form which two main blood vessels?

Answer 19

Middle cerebral arteries and the anterior cerebral arteries

Question 20

Middle cerebral arteries provide blood to…

Answer 20

the tip of temporal lobe, lateral surface of cerebral hemispheres and insula. Also supply globus pallidus, putamen, internal capsule, corona radiata, and caudate nucleus.

The MCA supplies all of the motor cortex (area 4) and the somatosensory cortex (areas 1, 2, 3) except the lower extremity LE area.

Question 21

The anterior cerebral arteries are joined near the rostrom of the corpus callosum by…

Answer 21

the anterior communicating artery

Question 22

The anterior cerebral arteries supply…

Answer 22

the medial surface of the cerebral hemisphere (i.e., the LE area) and deeper structures including the internal capsule, corpus callosum, and caudate nucleus.

Question 23

Components of the circle of Willis:

Answer 23

A. Basilar artery
B. Posterior cerebral arteries 
C. Posterior communicating arteries
D. Internal carotid arteries
E. Anterior cerebral arteries
F. Anterior communicating artery

Question 24

Blood supply of spinal cord (midline anterior spinal artery)

Answer 24

The midline anterior spinal artery, branches off the vertebral artery and supplies the anterior 2/3 of the upper cervical levels of the SC with blood from the vertebral artery.

Question 25

Blood supply of spinal cord (short and long circumferential branches)

Answer 25

branch off the anterior spinal artery and carry blood to the depths and lateral edges of the anterior 2/3 of the SC, including all of the ventral horn and reaching the base of the posterior horn. The area of supply includes a variable part of the lateral corticospinal tract.

Question 26

Blood supply of spinal cord (paired posterior spinal arteries)

Answer 26

branch off of the vertebral arteries or the posterior inferior cerebellar arteries. The posterior spinal arteries supply the posterior 1/3 of the SC with blood from the vertebral arteries. The supply area includes the dorsal horn, substantia gelatinosa, and also a variable part of the lateral corticospinal tract.

Question 27

Below the upper cervical levels, the 3 spinal arteries form anastomoses with…

Answer 27

radicular arteries which branch off of the aorta.

Question 28

The great radicular artery or artery of Adamkiewicz may provide the entire arterial supply for…

Answer 28

the lumbosacral SC. This artery is sometimes inadvertently damaged during thoracic surgery, resulting in ischemic myelyopathy, and rendering the subject paralyzed below the affected level of the spinal cord.

Question 29

Spinal arteriovenous malformations may result in…

Answer 29

low back pain, sensory or motor problems, and/or impaired micturition.

Question 30

The brain consumes approximately what percentage of the body’s oxygen?

Answer 30

20%

Question 31

The brain comprises only 2% of the body weight, yet receives approximately what percentage of the cardiac output?

Answer 31

15-20%

Question 32

What are the main factors that have an effect on cerebral blood flow (F)?

Answer 32

pressure gradient (P) and cerebral vascular resistance (R)

Question 33

What is the relationship between the pressure gradient and cerebral vascular resistance?

Answer 33

The relationship described by Ohm’s law.

In the case of blood flow, Ohm’s law is F = P/R

Question 34

Resistance to blood flow is a function of both…

Answer 34

Resistance to blood flow is a function of both blood viscosity and vascular resistance

Question 35

Pressure is regulated by…

Answer 35

circulatory reflexes (e.g., the baroreceptor reflex, mediated by CN X).