Week 1: Lecture 3- Meninges and ventricles Flashcards
What are the 3 meningeal layers that surround the CNS?
- Dura matter (outer)
- Arachnoid mater (middle)
- Pia mater (inner)
Which artery supplies dura mater?
middle meningeal artery
Which layer is below the skin and above the dura mater?
cranium
What are each of the 3 meningeal layers like?
- dura - tough, fibrous, protective layer
- arachnoid- thin, delicate, spiders-web like, vascular
- pia - microscopically thin, follows gyri and Sulci
what are the two layers of dura mater?
- periosteal dura mater
2. meningeal dura mater
What is the periosteal dura mater layer tightly adhered to?
skull
What is the meningeal dura mater layer tightly adhered to?
arachnoid mater
Where is CSF found?
sub-arachnoid space between the arachnoid and Pia mater
What is a dural fold?
At some areas, the inner dural layer (meningeal) separates from the outer dural layer (periosteal) and protrude int he cranial cavity forming double layered dural folds
What are the 3 dural folds called and where are they found?
- falx cerebri - located between the two hemispheres
- tentorium cerebelli - seperates cerebral hemispheres from the cerebellum
- falx cerebelli - separates two cerebellum
What is the falx cerebri attached to anteriorly and posteriorly?
anterior - crista Galli of the ethmoid bone
posterior - internal occipital protuberance
What is a sinus?
a channel
venous blood from brain and CSF travels through these channels
What are the names of the important dural venous sinuses?
- inferior sagittal sinus
- superior sagittal sinus
- straight sinus
- confluence of sinuses
- right transverse sinus
- sigmoid sinus
- cavernous sinus
Which sinus is formed from the falx cerebri?
superior sagittal sinus
What are denticulate ligaments?
projections from the Pia mater that attaches the spinal cord to the arachnoid mater, through the arachnoid mater and into the dura function is to secure spinal cord on either side
What is between the bone and the dura?
epidural space
Which of the following are real spaces and which are potential spaces?
- between the dura and the skull
- between the dura and the arachnoid
- subarachnoid space
- epidural space
- potential
- potential
- real - as it has blood vessels, CSF etc
- real - as it has fat inside
What is the space between the dura and the arachnoid?
subdural space - very thin potential space
what’s the difference between dura mater in the cranium and in the spine?
in the spine, dura mater has no periosteal component, just meningeal
What is CSF?
- blood derived
- clear, colourless fluid
- contains glucose and inorganic salts, little protein, few cells
- fills subarachnoid space and ventricular system of brain
What is CSF produced by?
produced in ventricles by the choroid plexus - specialised areas of ventricular lining
What is the function of CSF?
- buoyancy - brain and spinal cord float to reduce traction
- cushioning effect to dampen trauma
- transport of substances: nutrients, dissolved gases, removal of metabolites
- provides stable environment
What are ventricles in the brain?
-fluid filled cavities inside the adult brain
what are 3 important ventricles?
- lateral ventricles
- third ventricle
- fourth ventricle
What are each of the ventricles derived from in embryonic development?
lateral ventricle - telencephalon
3rd ventricle - diencephalon
4th ventricle - mesencephalon and myelencephalon
What connects the lateral ventricle to the 3rd ventrcile?
interventricular foramina (of Monroe)
What connects the 3rd ventricle to the 4th ventricle?
cerebral aquaduct
From which part of the ventricular system does CSF escape from?
foramina of luschka - lateral apertures on the 4th ventricle
the body of the lateral ventricle courses through which lobes?
frontal and parietal
Which lobe is the posterior horn of the LV found in?
occipital
Which lobe is the inferior horn of the LV found in?
temporal
Where is the 3rd ventricle found?
between two thalami
Where is the 4th ventricle found?
between pons (anteriorly) and cerebellum (posteriorly)
What is the choroid plexus?
- collection of blood vessels and specialised cells
- filters blood from the capillaries, change ion concentration, remove protein and produces CSF
Explain how CSF travels from the choroid plexus to the subarachnoid space?
- Produced by choroid plexus in lateral ventricle
- Flows through foramina of Monroe to 3rd ventricle
- Travels through cerebral aqueduct to 4th ventricle
- Flows through foramina of Luschka (lateral) and foramen of magendie (medial) to reach the subarachnoid space
- Uses the arachnoid granulations/villi to travel back
what are cisterns?
expansions of the subarachnoid space / wider areas
which site do we use to sample CSF and why?
The lumbar cistern
- because a needle can be inserted here with little risk of damaging CSF
- as the spinal cord ends before the dural sac ends so we can access the subarachnoid space and don’t puncture the spinal cord
How does venous blood from the superficial veins reach the internal jugular vein?
- Superficial vein
- Superior sagittal sinus
- Confluence of sinuses
- Transverse sinuses
- Sigmoid sinus
- IJV
How does CSF from the deep veins reach the internal jugular vein?
- deep veins
- internal cerebral veins
- great vein of galen
- straight sinus
- confluence of sinuses
- transverse sinus
- sigmoid sinus
- IJV
What condition might occur if there is a blockage in CSF circulation?
hydrocephalus:
CSF will accumulate upstream of blockage in ventricular system
What would happen if there is a blockage in the cerebral aqueduct?
hydrocephalus and expansion of the lateral and 3rd ventricle
