L.5 Flashcards
What makes up the ventricular system
- 2 lateral ventricles
- the 3rd ventricle
- the 4th ventricle
Where are the lateral ventricles located
cerebral hemispheres
What are the 4 main structures of lateral structures
- anterior horn
- posterior horn
- inferior horn
- body
What is the function of the septum pellucidum
separates lateral ventricles from each other
What is the function of corpus callosum
forms rood of ventricles
Where is the caudate nucleus located
forms the lateral wall of the ventricle
Where is the hippocampus located
lies on floor of the inferior horn
What is the function of the foramen of monro
communication between lateral ventricles and 3rd ventricles
Where is the third ventricle located
it is in between the thalamus and hypothalamus
What is the function of the cerebral aqueduct
it connects the 3rd and 4th ventricle
Where is the 4th ventricle located
between the pons/medulla and cerebellum
What is the function of the 4th ventricle
it is continuous with the central canal of spinal cord and allows CSF to flow down to spinal cord
What are 2 structures part of 4th ventricle
- foramina of Luschka
- foramen of Magendie
What is the function of the foramina of Luschka
2 lateral openings that allow CSF to exit into the subarachnoid space
What is the function of the foramen of Magendie
a single midline opening that allow CSF to flow into the subarachnoid space (cisterna magna)
Why are these foramina important
- they maintain the flow of CSF
- they prevent a buildup of CSF in the brain
What are the functions of the CSF
- cushions brain against trauma
- removal metabolites (metabolic waste) from CNS
- transport NTs and chemicals
- stable ionic environment for neuronal function
Where is the choroid plexus located
they are located in each ventricle of the brain
What are the function of choroid plexus
produces CSF
How is CSF produced
choroid plexus filters blood from internal carotid and basilar arteries to produce CSF
What is the structure of the choroid plexus
it has fenestrated capillaries surrounded by cuboidal epithelium for blood filtration
What is the blood CSF barrier
- tight junctions between epithelial cells
- prevent macromolecules from CSF
- permeable to water and CO2
What are the features of cuboidal epithelium
- microvilli = increase SA
- bidirectional transport
- specialised ependymal
- active transport or facilitated diffusion
Why is a stable ionic environment important for CSF
good for neuronal function
Outline the CSF circulation
- lateral ventricles –> interventricular foramen –> 3rd ventricle
- 3rd ventricle –> cerebral aqueduct –> 4th ventricle
- 4th ventricle –> Luschka and Magendie foramina –> subarachnoid space (cisterna magna)
Where does the CSF flow from and into
CSF flows from ventricles to the subarachnoid space
Where is the subarachnoid space located
located between the pia and arachnoid mater
What is the function of the subarachnoid space
transfer electrolytes into brain and removal of metabolites
What are arachnoid granulations
herniations of arachnoid membrane that allow CSF to drain from subarachnoid space into the venous sinuses
What is the function of arachnoid granulations
removal of excess CSF and metabolites
What happens if CSF pressure > venous pressure
- arachnoid granulation open
- allows CSF to flow into venous sinuses
- prevents blood pooling in subarachnoid space
What happens if venous pressure > CSF pressure
- arachnoid granulations close off
- stops CSF from flowing into the venous system
- prevents loss of too much CSF and maintains balance
What is the normal colour of CSF
clear
What does a yellow/pink colour of CSF mean
bleed into subarachnoid space (subarachnoid haemorrhage)
What does cloudy CSF mean
infection: cells and protein within CSF
Why is lumbar puncture performed at lower level in children
the spinal cord ends lower in children due to ongoing skeletal growth
At which vertebral levels is a lumbar puncture usually performed
L4/L5
What is hydrocephalus
the dilation of brain ventricles
What are the main causes of hydrocephalus
- blocked CSF circulation
- impaired absorption
- over-secretion CSF
What is the overall effect of hydrocephalus
increased intracranial pressure
What is the cause of non-communicating hydrocephalus
blockage within the ventricular system by a tumour or cyst
What is the effect of non-communicating hydrocephalus
CSF can’t reach the arachnoid space
In non-communicating hydrocephalus, which ventricles appear dilated
3rd ventricle but 4th ventricle would appear normal
What is Danfy-Walker syndrome
- obstruction within foramina od 4th ventricle
- dilation of latera, 3rd & 4th ventricle
What is the cause of communicating hydrocephalus
obstruction in the arachnoid villi
What is the effect of communicating hydrocephalus
movement of CSF into venous sinuses is impeded (impaired absorption)
