What does raised intra-cranial pressure mean?
Increase in pressure within the cranial cavity
What can cause an increase in intra-cranial pressure?
A raised ICP causes damage to what CNS structures?
What is the Monro-Kellie hypothesis?
The volumes of the brain, blood and CSF exist in equilibrium
An increase in one volume causes a DECREASE in the volumes of the others to compensate
So a brain tumour decreases the volume of the blood and CSF and also causes an increase in intracranial pressure (pressure increases as volume decreases)
What symptoms do people with a raised ICP tend to have?
blurry vision, double vision, loss of vision, papilloedema, pupillary changes
What is diplopia?
The optic nerve arises from which structure of the brain?
(thalamus + hypothalamus)
Which space is the optic nerve found in?
Name the layers of the CNS from outer to inner.
Dura mater (outer)
Pia mater (inner)
Between which layers of the CNS is the subarachnoid space found?
What fills the subarachnoid space?
Cerebrospinal fluid (CSF)
What does CSF do?
Nourishes the brain and removes toxins
Once the CSF has circulated in the subarachnoid space, where does it drain?
Dural venous sinuses
What structures in the arachnoid mater allow CSF to drain into the dural venous sinuses?
spaces which allow CSF to drain into venous circulation
Which important artery, supplying the brain, is found in the subarachnoid space?
Circle of Willis
At which level does the spinal cord end?
At which level does the subarachnoid space end?
What can be taken from the subarachnoid space to diagnose CNS diseases?
What is this procedure called?
At which levels can a lumbar puncture be performed?
Why are these areas safe?
Subarachnoid space but no spinal cord (cauda equina instead, which is much harder to damage)
How much CSF circulates in the subarachnoid space at any one time?
Where is CSF produced?
Choroid plexus of the lateral, third and fourth ventricles
CSF drains from the subarachnoid space via the ___ venous sinus, through ___ ___.
dural venous sinus
via arachnoid granulations
What secretes CSF?
Where is it found?
Lateral, third and fourth ventricles
The lateral ventricles are found on the right and left sides of the brain.
Where is the third ventricle found?
Which structure connects the third and fourth ventricles?
The cerebral aqueduct connects which structures of the brain?
Most CSF passes from the fourth ventricle to the ___ ___.
Most CSF passes from the fourth ventricle to the subarachnoid space?
Where does the rest of it go?
Where does CSF circulate once it has passed through the fourth ventricle?
Where is it then reabsorbed?
Dural venous sinuses
Where does the central canal go?
This is why you can get CSF from a lumbar puncture
The dura, arachnoid and pia maters are known as ___.
i.e the lining of the CNS