Question

Describe the flow of cerebro-spinal fluid (CSF).

Hint:

The CSF flow is crucial for maintaining the homeostasis of the central nervous system, providing cushioning and removing waste products.

Answer 1

Cerebrospinal fluid (CSF) is a clear, colorless liquid that surrounds the brain and spinal cord, providing cushioning and protection. The flow of CSF follows a specific path, starting from its production to its absorption. The flow of CSF is described as follows:
1. Production: CSF is primarily produced by the choroid plexus in the lateral ventricles of the brain. A smaller amount is also produced by the ependymal cells lining the ventricles. Approximately 500-700 mL of CSF is produced daily.
2. Ventricular System: From the lateral ventricles, CSF flows into the third ventricle through the interventricular foramen (Foramen of Monro). Then, it flows through the cerebral aqueduct (Aqueduct of Sylvius) into the fourth ventricle.
3. Subarachnoid Space: After leaving the fourth ventricle, CSF enters the subarachnoid space through the median aperture (Foramen of Magendie) and two lateral apertures (Foramina of Luschka). The CSF then circulates around the brain and spinal cord.
4. Absorption: CSF is absorbed into the venous system through the arachnoid villi located in the dural sinuses, particularly the superior sagittal sinus. The absorbed CSF enters the bloodstream, maintaining a balance in the CSF system.
5. Flow Regulation: The production and absorption of CSF are tightly regulated to maintain normal intracranial pressure (ICP). An imbalance in the production or absorption of CSF can lead to conditions like hydrocephalus.