cerebrospinal fluid circulation

Definition

Target type: biologicalprocess

The neurological system process driven by motile cilia on ependymal cells of the brain by which cerebrospinal fluid circulates from the sites of secretion to the sites of absorption. In ventricular cavities, the flow is unidirectional and rostrocaudal, in subarachnoid spaces, the flow is multi-directional. [GOC:mgi_curators, PMID:22100360, PMID:24229449]

Cerebrospinal fluid (CSF) circulation is a dynamic process that involves the production, flow, and absorption of CSF, a clear fluid that bathes the brain and spinal cord.

**Production:**

* CSF is primarily produced in the choroid plexuses, specialized structures located in the ventricles of the brain.
* The choroid plexuses are composed of epithelial cells that actively transport fluid and solutes from blood into the ventricles.
* The main components of CSF are water, electrolytes, glucose, and proteins.

**Flow:**

* CSF flows from the lateral ventricles to the third ventricle through the foramen of Monro.
* From the third ventricle, it flows through the aqueduct of Sylvius to the fourth ventricle.
* The fourth ventricle has three openings: the foramen of Magendie and the two foramina of Luschka, which allow CSF to flow into the subarachnoid space.

**Absorption:**

* The majority of CSF is absorbed into the venous system through arachnoid granulations, small protrusions of the arachnoid membrane that extend into the dural sinuses.
* Absorption occurs via a pressure gradient between the CSF and the venous blood.
* Some CSF may also be absorbed by lymphatic vessels.

**Functions:**

* **Protection:** CSF cushions the brain and spinal cord, protecting them from physical trauma and shock.
* **Buoyancy:** CSF reduces the weight of the brain, preventing it from pressing on the base of the skull.
* **Excretion:** CSF removes waste products from the brain and spinal cord.
* **Regulation:** CSF helps to regulate the intracranial pressure and the composition of the extracellular fluid surrounding the brain.

**Circulation Pathway:**

The overall circulation pathway can be summarized as follows:

1. Choroid plexuses produce CSF.
2. CSF flows from the lateral ventricles to the third ventricle and then to the fourth ventricle.
3. CSF flows from the fourth ventricle into the subarachnoid space.
4. Most of the CSF is absorbed into the venous system through arachnoid granulations.
5. A small amount of CSF may be absorbed by lymphatic vessels.

**Clinical Significance:**

Disruptions in CSF circulation can lead to various neurological conditions, such as:

* Hydrocephalus: an abnormal accumulation of CSF within the ventricles of the brain.
* Meningitis: inflammation of the meninges, the membranes surrounding the brain and spinal cord.
* Spinal fluid leaks: leakage of CSF from the spinal cord or brain, often due to trauma or surgery.

The proper functioning of CSF circulation is crucial for maintaining the health and function of the central nervous system.'
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