The Ventricular System & Circulation of CSF Flashcards
Ventricles:
- are
- derived from
- purpose
- small cavity/chamber
- derived from the expansion and
folding of the neural plate - to produce and distribute CSF
Ventricles Embryology:
The neural tube is formed as it
detaches from the epiblast = neurulation
The neural crest cells seal the remaining space at the cranial and caudal ends are called the neuropores
If the pores do not seal causes congenital abnormalities
What cells develop into the PNS?
What cells develop into the CNS?
- neural crest cells detach and create
the PNS - the neural tube creates the CNS
Formation of Brain Vesicles:
neural tube starts to expand into three balloons at the top (prosencephalon, mesencephalon and rhombencephalon)
the three balloons then develop into 5 different components, which then fold in on themselves to create the brain
the rest of the tube forms the spinal cord
Brain Flexures:
the five different components fold in on themselves: in the brain we have the cerebral hemispheres on top, then the midbrain and then the cerebellum
forms different flexures: midbrain flexures, pontine flexure
(hollow cavity)
Lateral ventricles are next to which parts of the brain
telencephalon and prosencephalon
Aquaduct is
the ventricular system near midbrain
Central Canal:
hole in the middle of the spinal cord
Foramen of Monroe are
2 holes that divide the lateral ventricles
INTERVENTRICULAR
Foramen of Magendie and Foramen of Luschka
foramina connect the interventricular system so that CSF can leave the sealed structure
The Ventricular Pathway:
The Ventricular Pathway:
Dandy-Walker Malformation:
- developmental problem with
ventricular system resulting in an
expanded fourth ventricle
Dandy-Walker Malformation:
What cells line ventricles?
Choroid cells = specialised ependymal cells
Ependymal cells = specialised glial cells
Choroid Cells:
- function
to produce cerebrospinal fluid (CSF)
Draw choroid plexus:
Label diagram on addendum A
Choroid plexus
one confluent tube system
Formation of CSF:
insert diagrams
First diagram blue = ventricles
green = ependymal cells
Second diagram shows fenestrated capillaries allowing substances to seep out into the extracellular space
in order for molecules to move from outside of capillaries and into CSf they have to pass through the choroid cells
they can not pass between the choroid cells because the choroid cells have tight junctions
Channels in choroid cells allow substances to pass into CSF.
Choroid cells also contain carbonic anhydrase which breaks down water into CO2 and H2
creates an acid, which can act as a buffer
CSF Production Cellular Level:
Water is broken down into bicarb which is pushed over by opposite flow of Na+ and K+
Creates fluid
CSF vs Plasma table
Blood Brain Barrier:
capillaries inside the brain are unfenestrated
three different aspects:
- thick basement membrane
- tight junctions between cells
- astroctyes are a different glial cells
which seal off the capillary hence
offer a protective mechanism to the
brain and are involved in cell
signalling
CSF Cisterns and the Venous System:
Glymphatic System
Arteries in the brain dive down into the brain, penetrating arteries creates a space between the tissue and and the vessels
move from periarterial to the perivenous space and then into venous sinuses
**occurs through channels called aquaporin 4 channels and through force/connective flow
Hydrocephaly on CT:
- fluid expands, squashes brain
because brain is sealed - in child head is still moldable as it is
growing, lateral ventricles will
expand, makes the skull expand =
make sure head circumference is
correct
Lumbar Puncture:
- diagnostic tool
- into cauda equina (around L3/4/5)
CSF Analysis:
