Cerebrospinal fluid is a clear, colorless fluid that occupies the subarachnoid space and the ventricular system within and around the brain and spinal cord. In a normal adult human being, there is about 100-150 ml of this fluid.
Production and circulation:
The cerebrospinal fluid is produces by the choroid plexus within the ventricular system of the brain, which is made of two lateral ventricles, a third ventricle and a fourth ventricle. It escapes the ventricular system through the three foramina in the roof of the fourth ventricle; the two lateral foramina of Luschka and a midline foramen of Magendie. From here it enters the subarachnoid space and circulate both upward (over the surfaces of the cerebral hemispheres) and downward (around the spinal cord).
Eventually the cerebrospinal fluid enters the bloodstream by passing into the arachnoid villi and diffusing through their walls.
The cerebrospinal fluid serves three basic functions:
- It serves to remove waste products associated with neuronal activity.
- It acts as a cushion providing a basic mechanical and immunological protection to the brain inside the skull.
- It serves a vital function in the cerebral autoregulation of cerebral blood flow.