The epithalamus's a dorsal posterior segment of the diencephalon (a segment in the middle of the brain also containing the hypothalamus and the thalamus) which includes the habenula, the stria medullaris and the pineal body. Its function's the connection between the limbic system to other parts of the brain. Functions Some functions of its components include the secretion of melatonin by the pineal gland. Components The epithalamus comprises the trigonum habenulæ, the pineal body, and the… (More on Epithalamus)