Formation and circulation of CSF
Definition
Cerebrospinal fluid (CSF) is a clear, colorless body fluid found in the brain and spine.
Produced in the choroid plexuses of the ventricles
Acts as a cushion or buffer for the brain's cortex,
Provides basic mechanical and immunological protection to the brain
Has a vital function in cerebral autoregulation of cerebral blood flow.
CSF formation
- secreted into each of the four ventricles by choroid plexuses
- choroid plexuses are areas where the lining walls of the ventricles are thin and have many capillaries
CSF presence
- in the four ventricles of the brain
- in the central canal of the spinal cord
- in the continuation of the central canal below the level of lower border of the L1 into the subarachnoid space
- in the subarachnoid space of the brain and spinal cord.
CSF drainage
- CSF is formed into the ventricles and the subarachnoid space and drained into the venous sinuses of the brain
- CSF passes into the venous sinuses through tiny diverticula of arachnoid mater which project into the venous sinuses called arachnoid villi (arachnoid granulations)
From the roof of the 4th ventricles CSF flows through foramina into the subarachnoid space.
Circulating force
CSF pressure is more than the venous pressure in the sinusoids;
If venous pressure becomes higher the arachnoid villi collapse and prevent the passage of blood constituents into the CSF.
Some reabsorption of CSF by the cells in the walls of the ventricles.
Force from :
Pulsating blood vessels
Respiration
Changes of posture
