abnormal lateral ventricle morphology dilated lateral ventricles MP:0000824 MP:0000825 MPheno.ontology dilated ventricle of cerebral hemisphere dilated ventriculus lateralis lateral ventricle dilation the luminal space of the lateral ventricles is increased in volume or area, usually with an increase in contained fluid, in the cavity in each of the cerebral hemispheres derived from the cavity of the embryonic neural tube; they are separated from each other by the septum pellucidum, and each communicates with the third ventricle by the foramen of Monro, through which also the choroid plexuses of the lateral ventricles become continuous with that of the third ventricle dilated brain ventricles