Blood supply of the brain

Question 1

List the 2 major arterial systems that supply the brain.

Answer 1

. The internal carotid arteries provide about 80%

2. The vertebral arteries provide 20%

Question 2

Describe how these system merge at the Circle of Willis. In normal conditions, is there significant collateral flow from one system to the other through the Circle of Willis?

Answer 2

The circle of Willis connects the Internal Carotid and Vertebral-Basilar Systems.
The posterior cerebral artery is connected to the internal carotid artery by the posterior communicating artery completing an arterial polygon called the circle of Willis.
Normally, little blood flows through the posterior communicating arteries.
In reality the communicating arteries vary in size and more often are not sufficient to ensure functional anastomosis.

Question 3

What are the areas of supply of each system? e.g. cerebrum, brainstem, cerebellum, spinal cord.

Answer 3

The internal carotid arteries provide about 80% Supply: Most of the telencephalon Much of the diencephalon

. The vertebral arteries provide 20% Supply: The brainstem The cerebellum Parts of the diencephalon The spinal cord The occipital and temporal lobes

Question 4

Describe the parts and course of the internal carotid artery (ICA), from outside the skull, through the skull, to its entry into the subarachnoid space.

Answer 4

Continuation of the common carotid artery. Has cervical and intracranial part. Ascends through side of the neck until it reaches the temporal bone where it veers anteriorly. In the carotid canal it gives a small branch ramus caroticotimpanicus.

passes through the cavernous sinus and the subarachnoid space at the base of the brain

Opthalmic branch: leaves the skull through the superior optic foramen. Gives central retinal artery.

Question 5

What foramen does Internal carotid artery enter the skull through? What bone? List the main branches of the ICA.

Answer 5

Traverses the temporal bone, entering the skull through the carotid canal

Gives rise to two smaller branches: The anterior choroidal artery. The posterior communicating artery. Continues as the middle cerebral artery (MCA). 1 st branch is the anterior cerebral artery (ACA).

Question 6

Describe the vascular territory served by the anterior cerebral artery. What are the major branches of the anterior cerebral artery?

Answer 6

The ACA arches posteriorly, following the corpus callosum, supplying the medial parts of the frontal and parietal lobes. Callosomarginal artery follows the cingulate sulcus. Continues as the pericallosal artery, which stays immediately adjacent to the corpus callosum

Question 7

Describe middle cerebral artery vascular territory. What are the major branches of the middle cerebral artery?

Answer 7

The MCA proceeds posteriorly in the lateral sulcus. It divides into a number of branches that supply the insula. Emerges from the lateral sulcus and spread out to supply most of the lateral surface of the cerebral hemisphere

Question 8

How many spinal arteries are there and what are their names?

Answer 8

The posterior spinal artery, The anterior spinal artery, The posterior inferior cerebellar artery (PICA).

Question 9

What foramen do the vertebral arteries enter the skull through? What are its major branches?

Answer 9

The vertebral arteries: Run rostrally (up) through the foramina of the lateral processes of the spinal vertebrae. Enter the skull cavity through foramen magnum

Question 10

Describe the major branches of the basilar artery.

Answer 10

Branches: Numerous unnamed branches. The anterior inferior cerebellar artery (AICA). The superior cerebellar artery (SCA).