Blood Supply to CNS Flashcards
Where does the common carotid ascend and where does it bifurcate?
Common carotid ascends on side of the neck and bifurcates at carotid sinus into external and internal carotids.
Where does the internal carotid ascend after bifurcating?
Through the carotid canal and it has a twisting path through foramen lacerum.
Why is the internal carotid so tortuous?
To accomodate for the twisting of the head
What are the branches of the internal carotid artery?
It gives 3 main branches:
The opthalmic artery
The posterior communicating artery
The anterior choroidal artery
It then continues before dividing into 2 terminal branches:
Middle cerebral artery (MCA)
Anterior cerebral artery (ACA)
What membranes does the internal carotid pierce?
The dura mater before moving forward and upward to pierce the arachnoid mater and enter the subarachnoid space.
Where do vertebral arteries ascend?
Along the transverse processes of the vertebrae before entering the cranial cavity through foramen magnum.
Which brain layers do the vertebral arteries pierce?
The dura and arachnoid mater.
What branches do the vertebral arteries give off?
Anterior spinal artery
Posterior spinal artery
Posterior inferior cerebellar artery
Both unite at pontomedullary junction to form the basilar artery.
Where does the basilar artery move?
Ascends along ventral groove of pons
What are the branches of the basilar artery?
Pontine arteries
Anterior inferior cerebellar artery
Superior cerebellar artery
Posterior cerebellar artery (exits midbrain at terminal branches)
Where do vertebral arteries arise from?
The subclavian arteries
Where do the vertebral arteries unite to form the basilar artery?
At the pontomedullary junction
Where are the anterior (carotid) and posterior (vertebral) systems connected?
At the circle of willis
What is the purpose of the circle of willis?
It provides redundancy for collateral circulation.
Which blood vessels form the circle of willis?
Anterior+posterior communicating arteries
Where is the circle of willis located?
Anterior to the midbrain
under the cerebral hemispheres
in interpeduncular fossa
within the subarachnoid layer.
What fraction of people have a complete circle of willis?
1/3rd of people
Which arteries supply the midbrain?
The basilar artery
Posterior cerebral artery
Superior cerebellar artery
Which arteries supply the pons?
Pontine branches of basilar artery
Superior cerebellar artery
Anterior inferior cerebellar artery
Which arteries supply the medulla oblongata?
Vertebral arteries
Basilar artery
Anterior spinal arteries
Posterior spinal arteries
Posterior inferior cerebellar artery
Which arteries supply the cerebellum?
Superior cerebellar artery
Anterior inferior cerebellar artery
Posterior inferior cerebellar artery
Where does the anterior spinal artery originate and where does it go?
Descends from vertebral arteries in anterior spinal fissure and supplies the ventral 2/3rds of the spinal cord
What does the anterior spinal artery supply?
The anterior 2/3rds of the spinal cord
Lower median medulla
Which spinal cord segments are underperfused by the anterior spinal artery?
T4/L1
Why are there underperfused structures in the spinal cord?
Due to the lack of pressure in the circulation (only 1 artery goes down this artery).