Blood Supply to the brain* Flashcards
Where are the cranial meninges
Below the skull
What are the 3 layers of the cranial meninges?
Dura mater, arachnoid mater, pia mater.
Explain the Dura Mater?
Latin for tough mother. Tightly bound to the cranium. The inner meningeal layer is in contact with the arachnoid mater.
The inner layer reflects off a certain point, extending into the cranium and returning. (Dural Folds).
Explain the arachnoid mater.
Covers the brain, providing a smooth surface that doesn’t follow the brain’s underlying folds.
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What is the subarachnoid space?
It extends between the arachnoid and the pia mater. Fibres extends from the arachnoid to the pia mater to bridge the gap.
Explain the pia mater.
Thin layer covering the brain. Tightly adhered to the brain and goes into every fold. Loosely connected to the arachnoid mater.
What is the extradural space?
A ‘potential space’ between the dura mater and the cranium.
The meningeal arteries are embedded in the outer (endosteal) dura mater.
What happens if the vessels are ruptured?
This results in bleeding into the extradural space causing a rapid localised increase in intracranial pressure (coning).
What are the 2 layers of the dura mater?
Endosteal layer = Outer layer which is tightly bound to the cranium.
Meningeal layer = Inner layer which is in contact with arachnoid mater.
What do the internal carotid arteries divide into?
they divide into the anterior and middle cerebral arteries.
What is the circle of Willis?
It connects with the internal carotid arteries with the vertebrobasilar system via communicating arteries.
It can act as alternative blood supply if major vessels are damaged.
What us a cerebrovascular accident?
A CVA is caused by disease/damage to the arteries which supply the brain (stroke).
What is an ischemic stroke due to?
It is usually due to a blood clot blocking the flow of blood.
What is a hemorrhagic stroke due to?
It is usually due to a burst blood vessel (aneurysm) or can be due to trauma (tearing).
What is venous drainage?
Veins empty into the venous sinuses, which are the spaces between reflections of the inner layer of the dura mater. The sinuses drain into the internal jugular veins.
