Diencephalon is made of three main parts: <span><span>1. </span>Thalamus which is a relay station for sensory input</span> <span><span>2. </span>Epithalamus which have the function in producing spinal fluid and in the secretion of melatonin by the pineal gland</span> <span><span>3. </span>Hypothalamus which links the endocrine with nervous system. </span> <span>There is also another structure inside diencephalon sometimes called the fourth structure. It is subthalamus which regulates skeletal muscle movements.</span>