lecture 2 - ventricles, meninges, csf Flashcards
broadly speaking, what are the ventricles?
four cavities and connecting channels
how do the ventricles develop?
from expansions of the lumen of the embryonic neural tube
are the ventricles continuous with one another? explain.
yes - and the central canal of the spinal cord, because of how they develop
describe the shape of the lateral ventricles
backwards ‘c’ shaped chambers (paired)
describe the component parts of the lateral ventricles
- anterior horn
- posterior horn
- inferior horn
- body
do the posterior or anterior horns lie closer together?
anterior horns lie closer to eachother, while the posterior horns are more separated
each component part of the lateral ventricles lies in a different lobe of the brain, list these.
ant horn: frontal lobe
post horn: occipital lobe
inf horn: temporal lobe
body: parietal lobe
where does the body of the lateral ventricles join the posterior and anterior horns?
at the atria
what is the choroid plexus?
- tissue that lines all of the lateral ventricles, but specifically the body and the inferior horns
- responsible for the production of CSF
what is the foramina of Monro?
- aka interventricular foramen
- passageway via which the lateral ventricles drain into the third ventricle
the head of the caudate nucleus forms which border?
lateral wall of the anterior horn
the body of the caudate nucleus forms which border?
most of the lateral wall of the body
the caudate tail forms which border?
lies in roof of the inferior horn
the thalamus forms which border?
floor of body
the genu of the corpus callosum forms which border?
anterior wall of anterior horn
the body of the corpus callosum forms which border?
roof of the anterior horn and the body
the septum pellucidum forms which border?
medial wall of the anterior horn and the body
the hippocampus forms which border?
most of the floor and medial wall of the inferior horn
where is the 3rd ventricle?
btwn the two thalami
describe the shape of the 3rd ventricle
narrow, slit like cavity
which secondary vesicle does the 3rd venticle form from?
diencephalon
what is the cerebral aquaduct?
passageway that connects the 3rd and 4th ventricles
where does the cerebral aqueduct pass through?
midbrain
what secondary vesicle does the cerebral aquaduct form from?
mesencephalon
what forms the walls of the 3rd ventricle?
medial surface of thalamus and hypothalamus
what forms the floor of the 3rd ventricle?
hypothalamus
what are the borders of the 4th ventricle?
- posterior to the pons and the rostral medulla
- anterior to the cerbellum
what is the 4th ventricle continuous with?
- cranial: 3rd ventricle (via cerebral aquaduct)
- caudal: central canal
what secondary vesicle foes the fourth ventricle form from
rhombencephalon
what secondary vesicle does the central canal form from
neural tube
what does the central canal pass through?
medulla, then sc
describe how CSF leaves the 4th ventricle
-most drains into the subarachnoid space via either:
( 1) foramen of Magendie (medial)
(2) foramen of Luschka (lateral)
-some leaks into the central canal of the sc
outline the cycle of CSF
- choroid plexus creates CSF in lateral ventricles
- drains via foramen of Monro to 3rd ventricle
- choroid plexus creates CSF in 3rd ventricle
- accumulates
- drains via cerebral aquaduct to 4th ventricle
- choroid plexus creates CSF in 4th ventricle
- accumulates
- drains via foramen of Magendie or Laschuka to subarachnoid space or drains into central canal
- flows around CNS
- eventually reabsorbed into bloodstream
what is the main take away from the cyle of CSF?
it is accumulating in each ventricle
what are the 3 meningeal layers?
dura matter, arachnoid matter, pia matter
what is the outermost layer? (superficial)
dura matter
what is the middle layer?
arachnoid matter
what is the innermost layer? (deep)
pia matter
which one of the cranial meninges is a double membrane?
dura
what are the two layers of the double membrane?
periosteal layer
meningeal layer
which dural layer is closer to the skull and which dural layer is closer to the brain?
skull - periosteal
brain - meningeal
are the dural layers relatively easy of hard to separate?
hard
during development, what happens to the dura matter?
it is reflected inwards, forming folds called the dural septa
what are the dural septa?
falx cerebri and tentorium cerebelli
what is the function of the dural septa?
function as scaffolding to help minimize excessive brain movement within the skull
where is the falx cerebri?
dural invagination into saggittal fissure
where is the tentorium cerebelli?
dural invagination into horizontal fissure
what is the subdural space
potential space between dura matter and arachnoid matter
what is the epidural space?
potential space between dura matter and bone (skull or vertebral collumn)
what is the subarachnoid space?
real space between the arachnoid matter and pia matter that is filled with csf and bvs (surrounds entire brain)
explain how the arachnoid matter is connected to the pia matter
denticulate ligaments: web-like threads of collagen and elastin fibres extend from the arachnoid matter down to the pia matter to secure it
describe the pia matter
thinnest, vascualarized protective layer attached firmly to the surface of the brain and the sc (even dips into fissures and sulci of the brain)
do all three meningeal layers cover both the brain and sc?
yes, except pia only reaches L1/L2
describe the composition of CSF
similar to blood plasma (‘watery broth’)
how is CSF formed?
as a filtrate from blood plasma by the choroid plexus
where is CSF reabsorbed back into circulation?
dural venous sinus (mainly superior saggittal sinus)
how is CSF reabsorbed back into circulation?
via arachnoid vili in the sinus
what is hydrocephalus?
the buildup of fluid in the ventricles of the brain - very deadly
what meningeal layer are the cisterns located in?
subarachnoid space
what are the spinal cisterns?
lumbar cistern
describe the lumbar cistern (3 facts)
- largest
- occurs because pia only reaches L1/L2
- where do spinal tap
what are the cranial cisterns?
pontine, cisterna magna, quadrigeminal, ambient, interpeduncular
what is the function of cisterns?
areas where CSF can accumulate to allow for lots of good stuff
where is the pontine cistern?
anterior and inferior to the pons, superior to the medulla
where is the cisterna magna?
inferior to the cerebellum, posterior to the medulla
where is the quadrigeminal cistern?
posterior to the midbrain
where is the ambient cistern?
lateral to the midbrain
where is the interpeduncular cistern?
anterior to the midbrain
where is CSF reabsorbed back into circulation?
internal jugular vein
are the dural venous sinuses connected?
yes