The dorsal posterior subdivision of the diencephalon. The epithalamus is generally considered to include the habenular nuclei (HABENULA) and associated fiber bundles, the PINEAL BODY, and the epithelial roof of the third ventricle. The anterior and posterior paraventricular nuclei of the thalamus are included with the THALAMIC NUCLEI although they develop from the same pronuclear mass as the epithalamic nuclei and are sometimes considered part of the epithalamus.