Definition
Cerebrospinal fluid (CSF) is a clear and colorless fluid. It is a watery broth similar in its makeup to blood plasma, from which it forms. The cerebrospinal fluid is a fluid that circulates throughout the central nervous system and is located between the brain and skull.
Purpose of CSF
The CSF has 2 important benefits to the central nervous system:
Circulation
- the cerbrospinal fluid delivers nutrients to the structures of the nervous system
- the cerebrospinal fluid removes wastes from the brain and spinal cord, detoxifying the environment of the nervous system
Shock Absorption
The cerbrospinal fluid protects the brain and spinal cord from trauma brought upon by movement, falls, blows, etc.
Where is CSF formed?
CSF is produced in the choroid plexus of the lateral, third and fourth ventricles. It is continually formed from the blood by the choroid plexuses. Choroid plexuses are capillaries hanging from the “roof” in each of the brain’s ventricles. The CSF in and around the brain and cord forms a watery cushion that protects the fragile nervous tissue from blows and other trauma.
CSF Circulation
The cerebrospinal fluid is continually moving inside the brain. From the two lateral ventricles where it circulates which is inside the cerebral hemispheres it flows into the third ventricles which is the diencephalon and then it passes through the cerebral aqueduct of the midbrain into the fourth ventricle located dorsal to the pons and medulla oblongata.
The amount of CSF that reaches that fourth ventricle continuously flows down into the central canal of the spinal. However, most of the fluids are circulating into the subarachnoid spaces through the three openings on the wall of the fourth ventricle. Then this fluid passes through the arachnoid villi to return to the dural sinuses.
Rate of CSF Formation and Drainage
The formation and the drainage of the cerebrospinal fluid occur at a constant rate in which the body maintains. Ordinarily, about 150 ml of CSF are formed and drained at a constant rate.
Changes in CSF Composition
Alterations in the composition of CSF or the presence of blood cells in the fluid may indicate infection, such as in meningitis or other brain pathologies such as presence of tumors or multiple sclerosis. To know if abnormalities are present in the CSF a sample should be obtained through lumbar tap, also known as spinal tap.
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