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cerebrospinal fluid
the fluid within the subarachnoid space, the spinal canal, and the four ventricles of the brain. It is formed continuously by the choroid plexuses in the ventricles, and, so that there will not be an abnormal increase in fluid amount and intracranial pressure, it is reabsorbed into the blood by the arachnoid villi at approximately the same rate at which it is produced. The cerebrospinal fluid helps protect the brain, spinal cord, and
meninges by acting as a watery cushion surrounding them to absorb the shocks to which they are exposed. There is a blood-brain barrier (also called the blood–cerebrospinal fluid barrier) that prevents harmful substances, such as metal poisons, some pathogenic organisms, and certain drugs, from passing from
the capillaries into the cerebrospinal fluid. See also cerebrospinal pressure and intracranial pressure.
Copyright 2007. An Elsevier publication. All rights reserved.
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