Quiz: Blood Supply of the Brain and Spinal Cord — 24 questions

1. Which artery is the largest branch of the vertebral artery and supplies the inferior cerebellum, medulla oblongata, and choroid plexus of the fourth ventricle?

A. Anterior spinal artery

B. Posterior inferior cerebellar artery

C. Anterior inferior cerebellar artery

D. Superior cerebellar artery

Answer: (B)

Explanation

The posterior inferior cerebellar artery is the largest branch of the vertebral artery and supplies all three listed regions. The anterior inferior cerebellar artery is instead a branch of the basilar artery.

2. What is the circle of Willis?

A. An arterial anastomotic ring in the interpeduncular fossa

B. A venous drainage channel within the cavernous sinus

C. A bony passage surrounding the internal carotid artery

D. A ventricular space beneath the cerebral hemispheres

Answer: (A)

Explanation

The circle of Willis is an arterial ring located in the interpeduncular fossa at the base of the brain. The interpeduncular fossa is the space containing the ring, not the ring itself.

3. What vascular function does the circle of Willis provide?

A. It directs venous blood from both hemispheres into the cavernous sinus

B. It supplies brain tissue through a single uninterrupted arterial channel

C. It permits blood from either arterial source to reach either cerebral hemisphere

D. It carries cortical blood directly into the ventricular system

Answer: (C)

Explanation

The circle of Willis allows blood entering through either the internal carotid or vertebral arteries to reach either cerebral hemisphere. Cortical and central branches then distribute blood into the brain substance, rather than the ring itself directly supplying all tissue.

4. Where does the internal carotid artery emerge from the cavernous sinus before entering the subarachnoid space?

A. On the lateral side of the posterior clinoid process

B. Through the inferior surface of the temporal bone

C. On the medial side of the anterior clinoid process

D. Within the center of the optic chiasm

Answer: (C)

Explanation

The internal carotid artery emerges from the cavernous sinus on the medial side of the anterior clinoid process before entering the subarachnoid space. The optic chiasm is nearby but is not the site from which the artery emerges.

5. Which description best identifies the great anterior medullary artery of Adamkiewicz?

A. It arises from intercostal arteries at upper thoracic levels, enters centrally, and supplies the upper cord

B. It arises from the vertebral artery in the neck, enters from the right, and supplies the posterior third of the cord

C. It arises from lumbar veins, enters from the left, and drains the lower cord into the vena cava

D. It arises from the aorta at lower thoracic or upper lumbar levels, enters from the left, and supplies much of the lower cord

Answer: (D)

Explanation

The artery of Adamkiewicz arises from the aorta at lower thoracic or upper lumbar levels, typically enters the cord from the left, and provides the major blood supply to the lower two-thirds. The alternative descriptions confuse it with other spinal vessels or with venous drainage.

6. Which sequence correctly describes the course and termination of the vertebral artery?

A. It arises from the basilar artery, passes through the lower six cervical transverse foramina, enters the jugular foramen, and forms the posterior cerebral artery.

B. It arises from the common carotid artery, passes through the upper six cervical transverse foramina, enters the foramen magnum, and forms the anterior spinal artery.

C. It arises from the subclavian artery, passes through the cervical spinal canal, enters the foramen magnum, and divides directly into the posterior cerebral arteries.

D. It arises from the subclavian artery, passes through the upper six cervical transverse foramina, enters the foramen magnum, and joins its counterpart to form the basilar artery.

Answer: (D)

Explanation

The vertebral artery originates from the first part of the subclavian artery, ascends through the transverse foramina of the upper six cervical vertebrae, enters the foramen magnum, and joins the opposite vertebral artery to form the basilar artery. The basilar artery is therefore the product of vertebral artery union, not the artery of origin.

7. Which description best identifies the middle cerebral artery?

A. It is a communicating branch that links the internal carotid to the posterior cerebral artery

B. It is an orbital branch that enters through the optic canal beside the optic nerve

C. It is the largest internal carotid branch and supplies the lateral hemisphere and most of the motor area

D. It is the smaller internal carotid branch and supplies the medial hemisphere and leg area

Answer: (C)

Explanation

The middle cerebral artery is the largest branch of the internal carotid artery and supplies the lateral surface of the cerebral hemisphere and most of the motor area. The medial cortex and leg area are associated with the anterior cerebral artery, while the communicating and orbital descriptions refer to different branches.

8. Where does the basilar artery divide into the two posterior cerebral arteries?

A. At the lower border of the pons

B. At the upper border of the pons

C. Within the foramen magnum

D. At the junction with the subclavian artery

Answer: (B)

Explanation

The basilar artery ascends in a groove on the anterior pons and divides at the upper border of the pons into the two posterior cerebral arteries. Its formation occurs lower down, where the two vertebral arteries unite at the lower border of the pons.

9. Which region is most directly associated with the territory of the posterior cerebral artery?

A. The inferolateral and medial temporal and occipital lobes, including the visual cortex

B. The anterior and inferior cerebellum, together with the upper medulla

C. The lateral frontal and superior parietal lobes, including the primary motor cortex

D. The inferior cerebellum, medulla oblongata, and fourth-ventricle choroid plexus

Answer: (A)

Explanation

The posterior cerebral artery supplies the inferolateral and medial temporal lobe and the lateral and medial occipital lobe, including the visual cortex. The other regions correspond mainly to territories of the anterior cerebral, anterior inferior cerebellar, or posterior inferior cerebellar arteries.

10. Which arteries provide most of the blood supply to the corpus striatum and internal capsule?

A. The central branches of the anterior cerebral artery

B. The superior and inferior cerebellar arteries

C. The medial and lateral striate branches of the middle cerebral artery

D. The posterior communicating and posterior cerebral arteries

Answer: (C)

Explanation

The medial and lateral striate branches of the middle cerebral artery supply most of the corpus striatum and internal capsule, with the anterior cerebral artery providing the remaining supply. Posterior circulation branches primarily contribute to territories such as the thalamus and brainstem.

11. Which set of arteries supplies the cerebellum?

A. The posterior cerebral, basilar, and posterior communicating arteries

B. The superior, anterior inferior, and posterior inferior cerebellar arteries

C. The anterior, middle, and posterior cerebral arteries

D. The vertebral, anterior spinal, and posterior spinal arteries

Answer: (B)

Explanation

The cerebellum receives its arterial supply from the superior cerebellar, anterior inferior cerebellar, and posterior inferior cerebellar arteries. The posterior cerebral and communicating arteries primarily contribute to cerebral or diencephalic territories, while spinal arteries mainly supply the medulla and spinal cord.

12. Which territory is principally supplied by the anterior cerebral artery?

A. The choroid plexus and internal capsule within the lateral ventricle

B. The orbital contents and structures surrounding the optic nerve

C. The medial cerebral cortex, including the leg area of the precentral gyrus

D. The lateral cerebral surface, including most of the motor area

Answer: (C)

Explanation

The anterior cerebral artery is the smaller terminal branch of the internal carotid artery and supplies the medial cerebral cortex, including the leg area of the precentral gyrus. The lateral surface and most of the motor area are supplied mainly by the middle cerebral artery.

13. How does the ophthalmic artery enter the orbit in relation to the optic nerve?

A. Through the inferior orbital fissure below and medial to the optic nerve

B. Through the superior orbital fissure above and medial to the optic nerve

C. Through the carotid canal behind and inferior to the optic nerve

D. Through the optic canal below and lateral to the optic nerve

Answer: (D)

Explanation

The ophthalmic artery arises as the internal carotid artery emerges from the cavernous sinus and enters the orbit through the optic canal below and lateral to the optic nerve. The superior orbital fissure is not the stated entry route for this artery.

14. Which arterial group supplies the thalamus mainly?

A. Branches of the posterior communicating, basilar, and posterior cerebral arteries

B. Striate branches of the middle cerebral and anterior cerebral arteries

C. Branches of the vertebral, anterior spinal, and posterior spinal arteries

D. Branches of the superior, anterior inferior, and posterior inferior cerebellar arteries

Answer: (A)

Explanation

The thalamus is supplied mainly by branches of the posterior communicating, basilar, and posterior cerebral arteries. The striate branches of the middle cerebral artery are instead the principal supply for much of the corpus striatum and internal capsule.

15. Which set of vessels is included in the circle of Willis?

A. Anterior communicating, anterior cerebral, and posterior communicating arteries

B. Facial, lingual, and ascending pharyngeal arteries

C. Middle meningeal, ophthalmic, and choroidal arteries

D. Superior cerebellar, inferior cerebellar, and middle cerebral arteries

Answer: (A)

Explanation

The circle of Willis includes the anterior communicating, anterior cerebral, internal carotid, posterior communicating, posterior cerebral, and basilar arteries. The other sets contain vessels that are not components of this arterial ring.

16. Which structural feature distinguishes cerebral veins from many systemic veins?

A. They have thin walls without muscular tissue or valves

B. They have thick walls with prominent muscular layers

C. They remain confined within the brain tissue during drainage

D. They contain valves that direct blood toward the heart

Answer: (A)

Explanation

Cerebral veins are characterized by very thin walls and lack both muscular tissue and valves before draining into cranial venous sinuses. The idea that they contain valves and prominent muscle reflects the documented contrast with many systemic veins.

17. Which arteries provide the four major arterial sources that contribute to the brain’s arterial supply?

A. Two middle cerebral arteries and two communicating arteries

B. Two external carotid arteries and two basilar arteries

C. Two anterior cerebral arteries and two posterior cerebral arteries

D. Two internal carotid arteries and two vertebral arteries

Answer: (D)

Explanation

The brain receives its major arterial input from two internal carotid arteries and two vertebral arteries, whose branches form anastomoses at the brain’s base. The circle of Willis is the resulting arterial network, not one of the four arterial sources.

18. Which sequence correctly describes the course of the internal carotid artery?

A. It ascends from the bifurcation, traverses the carotid canal and cavernous sinus, then divides intracranially

B. It ascends through the optic canal, crosses the orbit, then divides into cerebellar arteries

C. It begins in the vertebrobasilar system, crosses the dura, then enters the carotid canal

D. It descends from the bifurcation, passes through the jugular foramen, then divides in the neck

Answer: (A)

Explanation

The internal carotid artery ascends from the common carotid bifurcation, enters the skull through the carotid canal, passes through the cavernous sinus, and ultimately divides into the anterior and middle cerebral arteries. The terminal cerebral branches arise after the artery reaches the intracranial subarachnoid space, not in the neck or orbit.

19. A lesion affecting venous drainage from the lateral surface of a cerebral hemisphere would most directly involve which vessel and sinus?

A. The deep middle cerebral vein and straight sinus

B. The superficial middle cerebral vein and cavernous sinus

C. The superior cerebral veins and superior sagittal sinus

D. The internal cerebral veins and transverse sinus

Answer: (B)

Explanation

The superficial middle cerebral vein drains the lateral cerebral surface into the cavernous sinus. The superior cerebral veins also drain the lateral hemisphere, but they empty into the superior sagittal sinus instead.

20. Which course and connection characterize the posterior communicating artery?

A. It passes through the optic canal and joins the ophthalmic artery

B. It descends beside the facial nerve and joins the middle cerebral artery

C. It runs anteriorly below the optic nerve and joins the anterior cerebral artery

D. It runs posteriorly above the oculomotor nerve and joins the posterior cerebral artery

Answer: (D)

Explanation

The posterior communicating artery arises near the terminal internal carotid bifurcation, runs posteriorly above the oculomotor nerve, and joins the posterior cerebral artery. The anterior cerebral arteries are connected by the anterior communicating artery, not the posterior communicating artery.

21. What is the role of segmental spinal arteries in the vascular supply of the spinal cord?

A. They arise from deep cervical, intercostal, and lumbar arteries and give rise to radicular arteries accompanying spinal nerve roots

B. They arise from the internal carotid arteries and form the cerebral venous sinuses around the brain

C. They arise from the vertebral arteries and directly supply the posterior third without accompanying nerve roots

D. They arise from the aorta and form the great anterior medullary artery at every spinal level

Answer: (A)

Explanation

Segmental spinal arteries originate from deep cervical, intercostal, and lumbar arteries and produce anterior and posterior radicular arteries that accompany spinal nerve roots. The great anterior medullary artery is a particular vessel arising from the aorta, not a structure formed at every spinal level.

22. Which sequence correctly describes the formation and course of the internal cerebral veins?

A. Thalamostriate and choroid veins unite at the interventricular foramen, then the veins run posteriorly and unite beneath the splenium

B. Cerebellar and spinal veins unite at the foramen magnum, then the veins pass through the tela choroidea to the superior sagittal sinus

C. Superior and superficial middle cerebral veins unite in the cavernous sinus, then the veins run anteriorly beneath the corpus callosum

D. Deep middle cerebral and striate veins unite near the pons, then the veins ascend through the tentorium to the transverse sinus

Answer: (A)

Explanation

The internal cerebral veins begin from the union of the thalamostriate and choroid veins at the interventricular foramen, course posteriorly in the tela choroidea, and unite beneath the splenium. Their union forms the great cerebral vein, rather than involving the cavernous or transverse sinus at that stage.

23. An artery travels with the facial and vestibulocochlear nerves through the internal acoustic meatus. What structure does it supply?

A. The internal ear

B. The superior surface of the cerebellum

C. The anterior and inferior cerebellum

D. The medial and lateral occipital lobes

Answer: (A)

Explanation

The labyrinthine artery accompanies the facial and vestibulocochlear nerves through the internal acoustic meatus to supply the internal ear. Cerebellar arteries instead primarily supply regions of cerebellar tissue and nearby brainstem structures.

24. Which comparison correctly describes the territories supplied by the spinal arteries?

A. Both posterior spinal arteries and the anterior spinal artery supply equal halves of the spinal cord

B. Posterior spinal arteries supply the posterior third, while the anterior spinal artery supplies the anterior two-thirds

C. Posterior spinal arteries supply the anterior two-thirds, while the anterior spinal artery supplies the posterior third

D. Posterior spinal arteries supply the entire cord, while the anterior spinal artery supplies the nerve roots

Answer: (B)

Explanation

The posterior spinal arteries supply the posterior third of the cord, whereas the anterior spinal artery supplies the anterior two-thirds. Reversing these territories is the documented confusion associated with this distinction.