Brain Ventricle

Fluid chambers of the brain containing the cerebrospinal fluid.

The four ventricles are the two lateral ventricles in the telencephalon or cerebrum (1st and 2nd ventricles), the third ventricle in the diencephalon. (diencephalon )and the fourth ventricle in Rhombencephalon (lozenge brain). Various drugs that are effective centrally (i.e. in the central nervous system, i.e. in the brain and spinal cord) must first cross the barrier between blood and cerebrospinal fluid in order to be effective at the brain structures (see pharmacology).

https://de.wikipedia.org/wiki/Hirnventrikel _{(Wikipedia CC-BY-SA-3.0)}