Nervous system: The ventricular system and dura Flashcards
What structure synthesis CSF? Where is this structure found?
The choroid plexus
Found in each of the ventricles
Describe the location of the lateral ventricles
The pair of lateral ventricles are C-shaped and sit in the cerebral hemispheres - they have a temporal, frontal and occipital horn that sit in the respective lobes.
They are the largest of the ventricles and have the largest choroid plexus
Describe the flow of CSF through the ventricular system
The bulk of the CSF is synthesised in the lateral ventricles and passes through the inter-ventricular foramen (attaches the 2 lateral ventricles together) then enters the 3rd ventricle.
CSF drains from 3rd ventricle through the cerebral aqueduct (midbrain) down to the 4th ventricle, then CSF enters the subarachnoid space
Describe the location of the 3rd ventricle
The 3rd ventricle is squashed between the 2 halves of the thalamus, the hypothalamic nuclei and pineal gland sit next to the 3rd ventricle.
Describe the location of the 4th ventricle
Sits in the pons/medullary region deep to the cerebellum
The 4th ventricle is continuous with the central canal of the spinal cord (so narrow there is not significant CSF in it)
What is the difference between a T1 and T2 weighted MRI?
T1 picks up fat so fat appears white
T2 picks up H20 so CSF appears white
Name the layers of the meninges from inside to outside
Pia mata
Arachnoid mata
Dura mata - meningeal then periosteal
Describe the location of the meningeal layers
The pia mata covers the entire CNS (almost suction packed) so dips into all the sulci.
The arachnoid mata is loosely adhered to the CNS (dips down between the 2 hemispheres)
The meningeal layer is looser but still dips between the 2 hemispheres
The periosteal layer is adhered to the bone so no dip
Where is a subarachnoid haemorrhage?
What could cause this?
A bleed in the subarachnoid space (space between the pia mata and arachnoid mata)
Most commonly caused by a brain aneurysm
Where is a subdural haemorrhage?
What could cause this?
A bleed between the dura and the arachnoid mata.
Rupture of the bridging veins
Where is an epidural haematoma?
What can cause this?
A bleed between the dura mata and the skull
Caused by a middle meningeal artery bleed
Where are the dural venous sinuses found?
Between the meningeal and periosteal dura eg the superior saggital sinuses
Where do the dural venous sinuses drain?
The sinuses meet at the confluence (the occipital region) to make the transverse and sigmoid sinus which make the internal jugular vein
( The vast majority of blood drains this way)
Where is the inferior sinus located?
How does it drain?
Sits in the free edge of the falx cerebri and becomes the straight sinus to meet the confluence of sinuses
What is the location of the cavernous sinus?
The left and right cavernous sinus sit either side of the pituitary with intercavernous sinuses bridging the two.
What is the falx cerebi?
A fold of meningeal layer of dura mater that descends vertically in the longitudinal fissure between the cerebral hemispheres.
- attaches anteriorly at the crista galli
- attaches posteriorly at the upper surface of the cerebellar tentorium
What is the tentorium cerebelli?
An extension of the dura mata that separates the cerbellum from the occipital lobe
What is the diencephalon?
Region of the neural tube which includes forebrain structures such as the hypothalamus, thalamus, pituitary and pineal glands.
What is the anterior commissure?
A bundle of white matter that connects the two temporal lobes. Travels through the corpus callosum and plays a role in acute pain, memory, emotion, speech and hearing
What is the posterior commissure?
A bundle of white matter connecting the 2 cerebral hemispheres which is located on the dorsal aspect of the cerebral aqueduct. Has an important role in the direct and consensual pupillary light reflex.
