The diencephalon is one of two segments of the forebrain or prosencephalon (the other being the telencephalon which develops into the cerebrum). The diencephalon contains the thalamus, hypothalamus, epithalamus, sub-thalamus and the pineal gland. It is involved in relaying sensory information and impulses throughout the brain. The diencephalon is also involved in endocrine and limbic system functions.