Meningeal coverings, Ventricles and CSF Flashcards
What are the 3 types of meningeal coverings?
- Dura mater
- Arachnoid
- Pia
Pia + Arachnoid gives you what?
Leptomeninges
Function of Dura mater
- Provides mechanical strength
- Separates different intracranial components
- Contains venous sinuses
What kind of sense does the Dura Mater contain?
It is pain sensitive, with innervation by the trigeminal nerves anteriorly and by spinal nerve fibers posteriorly.
Function of the Arachnoid layer
Forms a barrier, which blocks the movement of items from one side of the barrier to another.
What suspends the brain in the skull cavity?
The arachnoid trabeculae, which insert into the pia mater..
These trabeculae are strands of collagenous connective tissue and scattered cells
Falx cerebri
Separates one hemisphere from the other
Tentorium Cerebelli
“Tent” which covers cerebellum
Tentorial notch/incisure
The anterior opening between the free edge of the tentorium cerebelli and the clivus for the passage of the brainstem.
Where is the sub-arachnoid space and what fills it?
It is found between layers of arachnoid and pia mater. It is filled with CSF and arteries and veins travel through it.
Arachnoid villi
In-pouchings of sinuses which allow CSF to exit the subarachnoid space.
Pia mater thicken up to form what 2 structures?
2 LIGAMENTS
(1) Denticulate
(2) Filum terminale
Function of denticulate ligaments
Helps to hold the spinal cord in place via lateral attachments.
Inner layer of cranial dura is continuous with…
Spinal dural sheath at foramen magnum
What fills the spinal epidural space?
Connective tissue and vertebral venous plexus
Percentages of origin for CSF
60%- Choroid plexus
30%- capillary bed
10%- metabolic
The 3rd ventricle is at the location of the…
Thalmus
The _____ forms a roof over the 4th ventricle.
Cerebellum
How does CSF end up surrounding the brain and spinal cord?
(1) Made in ventricles
(2) Exits via median/lateral apertures
(3) Enters cisterns
(4) Goes through tentorial notch
(5) enters venous sinuses via arachnoid villi
Choroid plexus
The BLOOD-CSF BARRIER
3 main components:
(1) Capillary -fenestrated
(2) Pia
(3) Choroid Epithelium
Choroid epithelium
Specialized ependymal, connected via tight junctions, numerous microvilli facing CSF, and numerous mitochondria.
The product of when ependymal cells get close to pia.
What looks like “Mickey Mouse” in cross-section?
The Midbrain
Everything made in the brain is absorbed and moves via the…
Arachnoid villi
Where does transfer of water in brain occur and via what type of process.
This transfer occurs mostly in the choroid fissure and is an ACTIVE process.
Choroid plexus is mainly in which ventricle(s)
Lateral 3rd and 4th
Ventricle right above the pons.
4th
The cerebral aqueduct is right above…
The 4th ventricle
Functioning of CSF
Mostly mechanical support (buoyancy).
Transport system/way to get rid of things.
Route for spread of neuroactive hormones
What happens when CSF does not absorb correctly?
Hydrocephalus- pathological state characterized by excessive accumulation of CSF in the ventricles/subarachnoid spaces
Function of circumventricular organs
Communication and balance creation between blood, brain parenchyma and CSF (interconnections to hypothalamus and brainstem)
Tanycytes
Specialized ependymal cells that overlie circumventricular organs
What kind of action is associated with AREA POSTREMA?
Sensory
What kind of action is associated NEUROHYPOPHYSIS?
Secretory
What should be in the epidural space?
There should truly not be any space at all. The only thing which should be present here are blood vessels.
When does bleeding normally occur in the epidural space?
Trauma, and usually in younger people due to more physical lifestyles.
Aneurysms are usually in the…
Subarachnoid space
What is the major bleeder oft associated with brain herniation?
The middle meningeal artery
