Meninges Flashcards
What are the layers of the meninges?
-Dura mater
-Arachnoid mater
-Pia mater
Describe the dura mater
-Is found immediately inside the bone
-Is slightly connected to the vault of the skull but can be just pulled away
Describe the arachnoid mater
-Thin and deep to the dura
-Not attached to dura, simply pushed up against it
-Gives off extensions that go into the lumen of sinuses called the arachnoid villi
What is the function of the extensions of the arachnoid villi?
Absorb CSF
Describe the pia mater
-Innermost layer that lies of the surface of the brain
-Very thin and very vascular
-Follows brain structure into sulci etc
-Also found around the spinal cord
What are the 3 types of extracerebral haemorrhages you can get?
-Extradural haemorrhage
-Subdural haemorrhage
-Subarachnoid haemorrhage
Describe what happens in an extradural haemorrhage including common cause and blood vessels involved.
Common cause = Fracture to the pterion
Middle meningeal artery runs between the dura and the bone in a groove near the pterion. If pterion fractures can cause rupture of middle meningeal artery.
Strips away dura from bone and get build-up of a blood clot
What might you notice about someone who has had an extradural haemorrhage, how long will this take to happen and who can this type of haemorrhage happen to?
-might become confused and conscious level will deteriorate as blood clot will press on brain
-Happens over a few hours
-can happen to anyone
What blood vessels are involved in a subdural haemorrhage, what commonly causes it and why?
-cerebral veins
-tends to happen in elderly after they’ve had a fall and hit their head
-Where the superior cerebral veins go into the sagittal sinus, they are anchored to the dura quite firmly
-A knock to the head can cause the brain to shift and tear the veins here
-Blood builds up between the arachnoid mater and the dura and get blood clot here
What might you notice about a patient who has has a subdural haemorrhage/when do onset of these symptoms begin? Explain why.
The conscious level of the patient tends to deteriorate after a couple of days into a few weeks
This is because the blood is venous blood and gradually oozes out
What blood vessels are involved in a subarachnoid haemorrhage and what is a common cause of this type of haemorrhage?
-Cerebral arteries
-A berry aneurysm (pathological swelling of BV) which can suddenly burst due to a localised weakness of the artery
-A small trauma can induce it e.g. falling off of a bike
Describe a subarachnoid haemorrhage in terms of what happens to the patient and the type of bleeding and where it is.
-Massive bleeding into the subarachnoid space underneath the brain
-Patient goes unconscious very quickly and this type of haemorrhage is recognised as a cause of sudden death
NOTE: will get blood stained CSF
Where do the cerebral arteries lie and what do they supply?
They lie on the underside of the brain in the subarachnoid space surrounded by CSF and supply blood to the brain
