Meninges, Dural Folds and Dural Venous Sinuses Flashcards
What are the 3 membranous layers that surround the brain?
Dura = tough fibrous membrane, firmly adhered to skull (outermost)
Arachnoid = soft translucent (middle)
Pia = thin, adherent to brain surface (innermost)
Name the potential spaces between the meninges and where they lie
Subarachnoid = space between arachnoid and pia
Subdural = space between dura and arachnoid
What is between the layers of the meninges?
Potential space
Can fill
What lies between the dura and inner table of bone?
Meningeal arteries = supply dura and bones of the skull
What are the layers of the dura?
Periosteal = endosteum lining inner table of skull (outer)
Meningeal = layer adjacent to arachnoid (inner)
What are dural folds?
Separations of the two layers of the dura
Meningeal layers pulling away from the periosteal layer = stuck together = fold
What are dural venous sinuses?
Space created at the top of a dural fold = becomes venous channels
Cranial floor = separation of the 2 layers of dura allowing for channels
Where do major dural venous sinuses lie?
Margins of borders of falx cerebri and tentorium cerebelli
Where is the CSF located?
Within the subarachnoid space (cerebral blood vessels also here)
Name the 2 important dural folds
Falx cerebri = between the 2 hemispheres
Tentorium cerebelli = tent sitting above cerebellum, covering posterior cranial fossa
What is the function of the dural folds?
Stabilise the brain
Rigid dividers
However when vol is added = brain compression = herniation = neurological symptoms/signs
How can you tear the dura?
Via crista galli bone (attachment of falx cerebri)
Potentially take the arachnoid layer with it = leaking of CSF through the nose
Where do cerebral veins that drain the brain drain into?
Dural venous sinuses – IJV
Name the venous sinuses
Where are the cerebral veins found?
Subarachnoid space
What layer is the dural venous sinus found?
Dural layer
What are bridging veins
Allow cerebral veins to traverse subdural space to drain into the dural venous sinus
Connect subarachnoid space to dural sinus
Bleeding can occur between which layers of the meninges?
All potential spaces
Extradural
Subdural
Subarachnoid
What is an intracerebral haemorrhage?
Bleeding within the brain tissue itself
What is a subarachnoid haemorrhage?
Usually ruptured branch of circle of willis = arterial circuit
Mixing with CSF
Hard to identify on CT after 24h = so sample CSF for presence of blood
Outline the radiographic appearance of extra and sub-dural haemorrhages
Extra = between bone and periosteal dura, lens shape, cant pass suture lines
Sub = bleed from bridging vein (risk increases with age), banana shape, can spread 1 half of skull
What permits entry of infections into the cranial cavity and brain?
Connection between the dural venous sinuses and extra-cranial veins of the scalp, orbit and face
