Ventricles of the Brain Flashcards
What are the functions of CSF?
1) Protection - acts as a cushion to limit damage.
2) Buoyancy - alleviate pressure off the base of the brain.
3) Chemical stability - low extracellular K+ for synaptic transmission.
How many ventricles are there?
1) Lateral ventricles (x2)
2) Third ventricle
3) Fourth ventricle
Where is the ventricular system derived from embryologically?
It is derived from the lumen of the neural tube.
Which cells produce CSF within the choroid plexus?
Ependymal cells.
How many horns are there in the lateral venticle? Where are they located?
Anterior horn - frontal lobe.
Lateral horn - temporal lobe.
Posterior horn - occipital lobe.
What are the lateral ventricles and third ventricle connected by?
The foramen of Monro.
Which structures are located within the third ventricle?
The right and left thalamus.
The anterior surface of the third ventricle contains two protrusions. These are…
1) Supra-optic recess - located above the optic chiasm.
2) Infundibular recess - located above the optic stalk.
How is the third and fourth ventricle connected?
Where is it located?
They are connected by the cerebal aqueduct.
It lies within the brainstem, at the junction between the pons and medulla oblongata.
Where does the CSF drain into from the 4th ventricle?
1) Central spinal canal - bathes the spinal cord
2) Subarachnoid cisterns - bathes the brain, between arachnoid mater and pia mater. Here the CSF is reabsorbed back into the circulation.
How is CSF produced?
It is produced when the blood is filtered by the ependymal cells (cuboidal epithelial cells). These cells filter the blood, removing plasma proteins, producing CSF.
How is CSF reabsorbed?
Drainage of the CSF occurs in the subarachnoid cisterns.
Small projections of the arachnoid mater, called arachnoid granulations protrude into the dura mater. This allows the CSF to drain into the dural venous sinuses.
Clinical relevance: hydrocephalus
Abnormal collection of CSF within the ventricles of the brain.
This is serious because chronic hydrocephalus can increase the intra-cranial pressure, leading to cerebral atrophy.
Types:
1) Communicating (non-obstructive) - No flow obstruction in the ventricles. This is usually due to functional impairmen of the arachnoid granules, such as fibrosis of the subarachnoid space, following a haemorrhage.
2) Non-communicating (obstructive) - Flow is obstructed in the ventricular system. A common site of obstruction is the cerebral aqueduct, connecting the third and fourth ventricles.
3) Hydrocephalus ex vacuo - ventricular expansion secondary to brain atrophy that is seen in neurodegenerative diseases, such as Alzheimers.
Treatment: reverse the cause.
