Meninges Flashcards
What are the three layers of the meninges?
Dura, arachnoid and pia
Where is the dura mater?
Outmost layer of the meninges, lying directly beneath the bones of the skull and vertebral column
Describe the dura mater
Tough fibrous membrane
What are the two layers of the dura mater?
Endosteal - lines inner surface of bones of cranium
Meningeal - lines endosteal layer inside cranial cavity
What is present between the two layers of the dura mater?
Dural venous sinuses - responsible for venous vasculature of cranium, draining into the internal jugular veins
Describe the arterial supply and venous drainage of the dura mater
Middle meningeal artery and ein
What innervates the dura mater?
Trigeminal nerve (V1, V2, V3)
What are the two types of haematomas involving the dura mater?
Extradural - between skull and endosteal layer of dura
Subdural - venous blood collects between dura and arachnoid mater
What usually causes an extradural haematoma?
Tearing of the middle meningeal artery
What does a subdural haematoma result from?
Damage to the cerebral veins as they empty into the dural venous sinuses
What does separation of the two layers of the dura mater form?
Dural folds, dural venous sinuses
What does the arachnoid mater consist of?
Layers of connective tissue
True or False:
The arachnoid is extremely vascular and very well innervated
False
Avascular
No innervation
What does the sub-arachnoid space contain?
CSF
What are arachnoid granulations?
Small projections of arachnoid mater into the dura which allow CSF to re-enter the circulation via the dural venous sinuses
Which is the thinnest meningeal layer?
Pia mater - tightly adhered to the surface of the brain and spinal cord
Which is the only covering to follow the contours of the brain?
Pia mater
Which layers of the meninges are highly vascularised?
Dura and pia
What are two examples of dural folds?
Falx cerebri and tentorium cerebelli
What is the purpose of dural folds?
Help to stabilise the brain and act as rigid dividers
What are dural venous sinuses?
Venous blood filled spaces created by separation of meningeal from periosteal layer of dura
What are some examples of dural venous sinuses?
Cavernous sinus, sigmoid sinus, transverse sinus
What are bridging veins?
Veins that connect sub arachnoid space into dural venous sinus
Why are subdural haematomas more commonly seen in elderly?
They experience cerebral atrophy so the subdural space increases and the veins that travel across them are longer
What is the cause of subarachnoid haemorrhage?
Usually trauma to cerebrial arteries - usually a branch of circle of willis
