bodily cavity, cavum, cavity - (anatomy) a natural hollow or sinus within the body

brain, encephalon - that part of the central nervous system that includes all the higher nervous centers; enclosed within the skull; continuous with the spinal cord

fourth ventricle - an irregular ventricle between the third ventricle and the central canal of the spinal cord

third ventricle - a narrow ventricle in the midplane below the corpus callosum; communicates with the fourth ventricle via the Sylvian aqueduct

lateral ventricle - either of two horseshoe-shaped ventricles one in each cerebral hemisphere; they communicate with the third ventricle via the foramen of Monro

cerebrospinal fluid, spinal fluid - clear liquid produced in the ventricles of the brain; fills and protects cavities in the brain and spinal cord

left ventricle - the chamber on the left side of the heart that receives arterial blood from the left atrium and pumps it into the aorta

right ventricle - the chamber on the right side of the heart that receives venous blood from the right atrium and pumps it into the pulmonary trunk

chamber - an enclosed volume (as the aqueous chamber of the eyeball or the chambers of the heart)