Meninges and CSF Flashcards
what do the meninges cover?
brain and spinal cord
what are the four layers of the meninges?
- dura mater
- arachnoid mater
- subarachnoid space
- pia mater
describe the dura mater
tough, thick covering
splits into periosteal and meningeal layer that enclose the dural venous sinuses
what is the sensory supply of the dura mater?
CNV (headaches)
what does the subarachnoid space hold?
CSF and blood vessels
what does the arachnoid mater have?
arachnoid granulations
what does the pia mater do?
adheres to brain
where can the subarachnoid space be accessed
lumbar puncture at L3/4 or L4/5 to obtain a CSF sample
what level does the spinal cord end?
L2
what level does the subarachnoid space end?
S2
what secretes CSF?
choroid plexus (epithelial pia in lateral and third ventricles)
how does CSF flow from the 3rd to the 4th ventricle?
cerebral aqueduct
where does the CSF drain after the 4th ventricle?
subarachnoid space and some into the central canal to the spinal cord
what reabsorbs CSF?
arachnoid granulations and passes into dural venous sinuses
define raised intracranial pressure
this is increased pressure in the cranial cavity (enclosed space so cannot stretch)
what does the constant intracranial volume consist of?
brain
blood
CSF
other components such as nerves, blood vessels
define Monro-Kellie hypothesis
balance of cranial contents
what can differences in contents of the cranial cavity cause?
damage
herniation
constriction of tissues
pushed out through gaps in the cranial cavity e.g. superior orbital fissure
what symptom do most people with raised ICP report?
vision change
what covers the optic nerves?
meninges
how does raised ICP affect the optic nerves?
it is transmitted along the subarachnoid space in the optic nerve sheath and can compress the optic nerve and central artery and vein of the retina
what affect does raised ICP on the optic nerve appearance have?
swollen/bulging optic discs (papilloedema)
