Blood supply to the brain

Question 1

What are the two paired arteries which are responsible for the blood supply to the brain?

Answer 1

• Vertebral arteries

- Internal carotid arteries

Question 2

What is the blood supply of parts of the CNS, such as the pons and spinal cord?

Answer 2

• Smaller branches from the vertebral arteries

Question 3

Which arteries do the internal carotid arteries originate from and at what level?

Answer 3

• The internal carotid arteries originate at the bifurcation of the left and right common carotid arteries, at the level of the 4th cervical vertebrae(C4)

Question 4

Describe how the internal carotids move into the brain?

Answer 4

• They move superiorly within the carotid sheath, and enter the brain via the carotid canal of the temporal bone, they do not supply any branches to the face or neck

Question 5

Describe the movement of the internal carotids with relation to the cavernous sinus?

Answer 5

• Once in the cranial cavity, the internal carotids pass anteriorly through the cavernous sinus

Question 6

What does each ICA give rise to?

Answer 6

Distal to the cavernous sinus, each ICA gives rise to:

• Ophthalmic artery - Supplies the structures of the orbit
• Posterior communicating artery , acts as an anastamotic ‘connecting vessel’ in the circle of willis
• Anterior cerebral artery - Supplies part of the cerebrum

Question 7

What do the internal carotids continue as?

Answer 7

• The middle cerebral artery, which supplies the lateral portions of the cerebrum

Question 8

Where do the vertebral arteries arise from?

Answer 8

• Arise from the subclavian arteries, medial to the anterior scalene muscle

Question 9

Describe the path of vertebral arteries into the brain

Answer 9

• They ascend up the posterior side of the neck, through holes in the transverse processes of the cervical vertebrae, known as foramen transversarium
• The vertebral arteries enter the cranial cavity via the foramen magnum

Question 10

What are the branches of the vertebral arteries within the cranial vault

Answer 10

• Meningeal branch - Supplies the falx cerebelli, a sheet of dura mater
• Anterior and posterior spinal arteries - Supplies the spinal cord, spanning its entire length
• Posterior inferior cerebellar artery - Supplies the cerebellum

Question 11

What do the two vertebral arteries converge to form

Answer 11

Basilar artery

Question 12

How does the basilar artery terminate

Answer 12

• By bifurcating into the posterior cerebral arteries