noun, plural: cerebrospinal fluids
The cerebrospinal fluid is a body fluid found in the brain and the spinal cord. In particular, it fills the brain ventricles, cisterns, and sulci. It also fills the central canal of the spinal cord. It is produced by specialized ependymal cells in the choroid plexuses. It is produced daily at a rate of about 25 mL per hour. To keep the 125-150 mL volume, it is constantly reabsorbed.1
The cerebrospinal fluid returns to the vascular system via the arachnoid granulations, i.e. small protrusions of the arachnoid mater into the dural venous sinuses of the brain. Through these protrusions, the cerebrospinal fluid is permitted to exit the subarachnoid space and then enter the bloodstream.
Analysis of the cerebrospinal fluid can be accomplished using lumbar puncture. The presence of white blood cells or bacteria within the cerebrospinal fluid is a possible indication of bacterial infection (meningitis).
1 Wright, B. L. C., Lai, J. T. F., & Sinclair, A. J. (2012). "Cerebrospinal fluid and lumbar puncture: a practical review". Journal of Neurology. 259 (8): 1530–1545.