Main Entry: fourth ventricle Function: noun : a somewhat rhomboidal ventricle of the posterior part of the brain that connects at the front with the third ventriclethrough the aqueduct of Sylvius and at the back with the central canal of the spinal cord
fourth ventriclen. An irregular cavity that extends from the obex to a communication with the sylvian aqueduct and is enclosed between the cerebellum dorsally and the tegmentum of rhombencephalon ventrally.
