Fluid Chambers

The four ventricles are the two lateral ventricles in the cerebrum (1st and 2nd ventricles), the third ventricle in the diencephalon and the fourth ventricle in the rhombic brain (the rhombic brain forms the rearmost part of the brain and establishes the connection to the spinal cord). It consists of the posterior brain or cerebellum and bridge as well as the medulla oblongata). Various drugs effective centrally (i.e. in the central nervous system) must cross the barrier between blood and cerebrospinal fluid in order to be effective on the brain structures (see pharmacology).