T1 L13: Ventricular system and CSF Flashcards
What 2 structures are continuous with the ventricular system of the brain?
The subarachnoid space and central canal
What does the mantle layer of the neural tube become?
The brain parenchyma
What does the lumen of the neural tube become?
Ventricles and the central canal
What does the ependymal layer of the neural tube do?
It lines the ventricles and central canal
Which ventricle is surrounded by the Telencephalon?
The lateral ventricles
Which ventricles is surrounded by the Diencephalon?
The 3rd ventricle
Which ventricle is surrounded by the Metencephalon?
The 4th ventricle
Which 4 structures are the lateral ventricles divided into?
The body, anterior horn, posterior horn, and inferior horn
Which lobe is the body of the lateral ventricles located?
In the Parietal lobe
Which lobe is the anterior horn of the lateral ventricles located?
Frontal lobe
Which lobe is the posterior horn of the lateral ventricles located?
In the occipital lobe
Which lobe is the inferior horn of the lateral ventricles located?
In the temporal lobe
How does the CSF appear on a T1-weighted MRI?
dark
What is the function of the corpus pellucidium?
It separates the bodies of the lateral ventircles
Where is the corpus collosum compared to the corpus pellucidium?
Corpus collosum sits like a roof above corpus pellucidium
Where is the Hippocampus found?
In the floor of the lateral horn
How do the lateral ventricles communicate with the 3rd ventricle?
Through the interventricular foramen (Formen of Monro)
What 2 structures does the fornix connext?
The mamillary bodies and the hippocampus
What separates the 2 Thalami?
The 3rd ventricle
Which structure creates the roof of the 3rd ventricle?
The fornix
Which structure allows communication between the 3rd and 4th ventricles?
The cerebral aqueduct (aqueduct of Sylvius)
What surrounds the 3rd ventricles?
The midbrain
What surrounds the 4th ventricle?
The hindbrain
What are the 3 foramina that exit into the subarachnoid space?
2x Formain of Luschka
1x Foramina of Magendie
Where are the foramina of Luschka?
Lateral. Sit very close to the Cerebellar peduncles
Where is the foramina of Magendie?
In the middle, in between the olives
What are the top 2 colliculi for?
Eyes
What are the bottom 2 colliculi for?
Ears
What are the 4 main functions of the CSF?
- Hydraulic buffer to cushion brain against trauma
- Vehicle for removal of metabolites from CNS
- Stable ionic environment for neuronal function
- Transport of neurotransmitters and chemicals
Where is CSF produced?
The choroid plexus
Where is the Coracoid plexus found?
Throughout the ventricles
What is the function of the Choroid plexus?
It produced CSF and filters blood from branches of the internal carotid and basilar arteries
Describe the structure of the Choroid plexus
A capillary network surrounded by cuboidal epithelium
How is CSF produced?
Blood is filtered through fenestrated capillaries and components are transported through the cuboidal epithelium and into ventricles
What lines the ventricles?
The Ependymal layer of cells
What is the function of tight junctions between epithelial cells of the Choroid plexus?
To prevent macromolecules from entering the CSF. Only permeable to H2O and CO2. This forms the blood-CSF barrier
Describe the structure of Ependymal cells
Have microvilli to increase surface area. Are full of proteins that allow for active transport of CSF components. They are bidirectional
How many proteins are there in CSF?
Tiny amount
What is the cisterna Magna?
The subarachnoid space that drains below the cerebellum
Where is the subarachnoid space?
Between the pia and arachnoid layer
Why is it important that the CSF has contact with the brain parenchyma?
So that electrolytes can be transferred and metabolites can be removed
How does CSF appear on a T2-weighted MRI?
White
What are arachnoid granulations?
Herniations of the arachnoid membrane through the dura mater into the venous sinuses mainly within the superior sagittal and transverse venous sinuses
What is the function of the Arachnoid granulations?
They allow for removal of excess cerebrospinal fluid and metabolites
Where is the CSF pressure greater, in the subarachnoid space or the venous sinuses?
In the subarachnoid space which prevents blood pooling in the subarachnoid space
What happens to the arachnoid granulations when the pressure is too great?
The tips of the granulations close off and act as a one-way valve so CSF can’t get into the arachnoids
How much CSF is produced each day?
600-700ml (~0.5ml/min)
How much CSF is found in ventricles?
~25ml but its continuously moving and replaced. Excess is absorbed by arachnoid granulations
What does yellow/orange/pink CSF indicate?
A subarachnoid bleed (A big bleed affecting the carotid arteries).
Indicates the breakdown of RBC’s and release of haemoglobin
What is Xanthochromia mean in terms of CSF disease?
Yellow/orange/ink CSF
What does cloudy/Turgid CSF indicate?
Bacterial meningitis
What colour CSF does multiple sclerosis cause?
Cloudy CSF
Where on the spine is a lumbar puncture taken and why?
At the lumbar cistern (L3/4) because there is no spinal cord and the dorsa and ventral veins will just move out of the way so there less of a risk of injury
At what level is a lumbar puncture taken is children and why?
At L4/5 because there is the possibility you could hit the spinal cord since they’re still developing
What is Hydrocephalus?
A dilation of the brain ventricles caused by a blocked CSF circulation, impaired absorption, or over secretion. This causes an increase in intracranial pressure
What are the symptoms of Hydrocephalus?
Headaches, vomiting, visual disturbances, swelling of the optic disc (papilledema), seizures, altered cognition, balance and coordination problems
Is hydrocephalus congenital or aquired?
Both
What is non-communicating hydrocephalus?
A failure of communication between ventricles and the arachnoid space because of a a blockage within the ventricular system causing the CSF to stop circulating over the surface of the brain. It’s caused by tumour, cysts, stenosis
`What is the surgical solution for non-communicating hydrocephalus?
Inserting a shunt to reduce intracranial pressure
What is Dandy-Walker syndrome?
A congenital malformation of the cerebellum causing an obstruction within the foramina of the 4th ventricles. It causes symmetrical dilation of the ventricles. In infancy a baby’s head will become enlarged and shunt has to be inserted
What is communicating hydrocephalus?
An obstruction in the arachnoid villi causing the movement of CSF to be impended. It’s caused by impaired absorption following subarachnoid haemorrhage, trauma, or bacterial meningitis
