Vasculature of the Brain Flashcards
How do parts of the brain in the anterior and middle craial fossae receive their blood supply?
Internal carotid artery branches.
How do the parts of the brain in the posterior cranial fossa getting their blood supply?
Through the branches of vertebral and basilar arteries.
How is the basilar artery made? Describe the journey of the vertebral artery. What does the basilar artery turn into?
By the joining of 2 vertebral arteries. The 2 vertebral arteries goes into the head through the foramen magnum and then converge behind the clivus to become the basilar artery. The basilar artery turns into the 2 posterior cerebral arteries.
What is the “circle of willis?” Physiologically why is this important?
A vascular ring that connects the carotid and basilar arteries. As a result if there is stenosis in one artery there can be compensation by increasing the “collateral blood flow” through the other artery.
What does the internal carotid artery bifurcate into?
The anterior and middle cerebral artery.
Name the 4 regions of the internal carotid artery, and describe it.
- Cervical part, in the lateral pharyngeal space.
- Petrous part: this is the part that makes a 90 degree angle as it dives into the carotid canal of the petrous bone
- Cavernous part: the part starting from when the ICA dives out of the petrous bone and follows the S shaped curve in the cavernous sinus.
- Cerebral part: located in the chiasmatic cistern of the subarachnoid space.
Which part of the internal carotid does not give up branches? What are the segments of the ICA called (the C designations).
Cervical part of the ICA. C1 and C2 are on the cerebral part of ICA, the supraclinoid segments.
C3-5 are infraclinoid and located in the cavernous sinus.
Clots ejected from the left heart will generally end up where in the brain as an embolus?
Frequently embolizes in the middle cerebral artery.
What are the common areas of stenosis and occlusions in the blood supply to the brain?
Vertebral artery, carotid biforcation, carotid siphon, and middle cerebral artery. All of these are bifurcations.
Despite the variations what are the components of arteries that make the circle of willis
Anterior, middle and posterior cerebral arteries, anterior and posterior communicating arteries, internal carotid and basilar arteries.
Describe the involvement of ICA and the circle of willis.
The 2 ICA comes in and splits into the anterior and middle cerebral arteries, on their respective side. The 2 anterior arteries then become connected via the anterior communicating artery. The 2 middle cerebral arteries becomes connected to the posterior cerebral artery via posterior communicating artery.
Describe the role of basilar artery in the circle of willis.
Basilar artery splits into 2 posterior cerebral arteries, and each of these arteries become connected to the middle cerebral artery via the posterior communicating branch.
Name the 2 abnormalities you can see with anterior cerebral artery.
The anterior communicating branch between them can be absent. Both the anterior communicating branch can arise from only one side of the ICA in 10% of the cases.
What can be abnormal in the posterior communicating artery?
One or both of them can be missing or hypoplastic in 10% of the cases.
What can be seen abnormally in the posterior cerebral artery?
Can be missing or hypoplastic.
What is the concept of the “subclavian steal?”
There is a stenosis in the left subclavian artery proximal to the off shoot of the vertebral artery. So when there is increased O2 demand to the left hand, the blood flow from the vertebral artery can reverse and flow into the left side rather than to the brain –> cause feelings of lightheaded-ness.
Before fusing to become the basilar artery, what are the off shoots coming off of the vertebral artery/basilar artery before the bifurcation into the posterior cerebral a.? (there are 5)
Anterior and posterior spinal arteries, superior, anterior inferior and posterior inferior cerebellar arteries.
Where do the Superior, anterior inferior and posterior inferior cerebellar arteries come from? The anterior spinal artery?
Each vertebral artery gives off the posterior inferior cerebellar artery. Then, proximal to the vertebral arteries fusing into the basilar artery, an off shoot from each side of the vertebral arteries fuse to form the posterior spinal artery. The large arteries coming off the basilar artery in the middle is the Anterior inferior cerebellar artery. Just before the basilar artery bifurcates, the superior cerebellar artery bifurcates.
