The Eye and Raised ICP Flashcards
what are meninges?
protective coverings of the brain and spinal cord
what are the three layers of the meninges?
dura mater
arachnoid mater
pia mater
what provides the sensory nerve supply to the dua mater?
CN V
what is enclosed in the dura mater?
the dural venous sinuses
what are the two layers the dura mater splits into around venous sinuses?
periosteal layer (outer) meningeal layer (inner)
what does the pia mater adhere to?
the brain and any vessels entering/leaving
what is found between the arachnoid mater and the pia mater?
the subarachnoid space
what is found in the subarachnoid space?
CSF
blood vessels
how can the subarachnoid space be accessed clinically and why would this be done?
lumbar puncture
to get a CSF sample
where is a lumbar puncture done?
L3/4 or L4/5 levels
when does the subarachnoid space end?
vertebral level S2
what are the four ventricles of the brain?
lateral x 2 (left and right)
third ventricle
fourth ventricle
what secretes CSF?
the choroid plexus in the lateral and third ventricles
what connects the third and fourth ventricles?
the cerebral aqueduct
how is CSF reabsorbed and where?
via arachnoid granulations
into the dural venous sinuses
what is raised ICP?
increased pressure in the cranial cavity
what causes raised ICP?
increased pressure either in the CSF or within the brain itself
why is raised ICP a serious emergency?
can damage the brain and spinal cord by compressing them
what is a common symptom experienced by patients with raised ICP?
visual problems
what is CN II?
the optic nerve
what covers CN II?
meninges
what does the optic nerve being surrounded by meninges mean?
increased ICP will be transmitted around the optic nerve = results in papilloedema
what is papilloedema?
swollen optic discs
what are dural septae?
folds of dural matter that create septae in the cranial cavity
