Superior view of right lateral ventricle at the interventricular foramen of Monro. The roof of the lateral ventricle is formed by the corpus callosum and has been removed to visualize the thalamostriate vein and choroid plexus at the floor. The fornix forms the lateral boundary of the ventricle and the choroid plexus is located medially. Cerebrospinal fluid produced by the choroid plexus flows through the interventricular foramen of Monro to enter the midline third ventricle. (Image courtesy of AL Rhoton, Jr.)