the meninges and vasculature Flashcards
remember the 3 structures that for the meninges
duramater - periosteal layer covering inner skull
arachnoid - web structured fluid filled
pia mater- delicate, covers surface of brain
where does the dural venous sinus structure sit in the brain
sits within the dura mater
what structure separates the 2 cerebral hemispheres and what tissue is it found in
- falx cerebri (that sits in the longitudinal fissure)
what structure separates the cerebrum from the cerebellum
cerebellar tentorium
find and label all the components of the dual venous sinus system
what are the 11 ranging purposes of CSF
- buoyancy of brain, spinal cord, nerves
- volume adjustment in cranial cavity
- nutrient transport
- protein/peptide transport
- brain volume regulation through osmoregulation
- buffering effect against external forces
- signal transduction
- drug transport
- immune system control
- elimination of metabolites and unnecessary substances
- cooling of heat generated by neural activity
the choroid plexus produces around 50% of CSF, how much CSF is secreted into the ventricles by ependymal cells
500mls per fay
remember that the CSF/ ventricles is continuous with the subarachnoid space
what do you call that hole seen in the 3rd ventricle
interthalamic adhesion
what is hydrocephalus and what causes it
- build up of fluid in brain
- occurs when theres blockage within the ventricular system OR
- reduced rate of reabsorption of CSF
what can hydrocephalus look like on MRI
Enlarged ventricles
what are the 3 types of strokes
ischaemic (blocked vessel supplying brain with blood)
hemorrhagic (ruptured weakened blood vessel)
transient ischemic attack (ministoke, temporary clot)
what is a watershed cerebral infarction/ border zone infarcts
- infarctions that occur at border between cerebral vascular territories
- unique ischemic lesions which are situated along the border zones between the territories of the major cerebral arteries.w
why do watershed cerebral infarctions occur/ prone to infarct. What percentage of strokes does it account for
- accounts for 5 - 10% of cerebral infarctions
- occurs as at the border between cerebral vascular territories is where the tissue is furthest from arterial supply and thus most vulnerable to reductions in perfusion
what is hypoperfusion
reduced blood flow
watershed cerebral infarct is primarily due to hypoperfusion, however there is another factor that contirbutes. what is it>
micro emboli from inflamed atherosclerotic plaque (a small particle, often a blood clot, that becomes caught while traveling through the bloodstream and can cause blockage in a blood vessel. )
what does a watershed infarct look like on CT/MRI
- longitudinal darkened strip in the brain (due to infarct at the vascular borders)
where is the most common area to get a stroke
middle cerebral artery (as it is a continuation of the inferior cerebral artery)
compare the difference in a subdural and extradural haematoma as seen on scan
extradural/epidural haematoma = lemon shaped on edge
subdural haematoma = banana shaped wedge on edge of brain
what type of blood is found in an extradural haematoma
- arterial blood (middle meningeal artery affected)
what type of blood is found in subdural haematoma
- venous blood ( often ruptured cortical bridging vein)
compare the speed of expansion of a sub/epi dural haematoma
extradural = rapidly expanding
subdural = slowly expanding
subdural haematoma many cross suture line but epidural will not.
what is the usually cause of a sub or epidural haematoma
subdural = convolution of gyri and sulci, torn cerebral vein
epidural = skull fracture (especially at pterion) (causing meningeal artery to break)
refer back to all the images screenshotteds and fully recognised the cerebral artery, circle of willis, branches of aorta, dual vein structures, etc
