Question

Epithalamus is situated on the
(a) Roof of diencephalon
(b) Lateral wall of diencephalon
(c) Dorsal side of optic lobes
(d) Floor of diencephalon

Answer 1

Hint: A division of the forebrain which consists of four different parts. It encloses a third ventricle where thalamus serves as a relay center. Epithalamus plays a role in conduction of its conducting systems.

Complete answer:
Diencephalon is divided into four components- the thalamus, the subthalamus, the hypothalamus, and the epithalamus. In epithalamus ‘epi’ means ‘upon’ thus, it forms the roof of the diencephalon which is the part of the forebrain. Epithalamus consist of habenular nuclei, habenular commissure, stria medullaris and pineal gland. It is associated with circadian rhythms of sleep wake cycle and regulates secretion of melatonin by the pineal gland.

- The forebrain has two main parts-diencephalon also known as the prosencephalon and cerebrum also known as telencephalon.
- The diencephalon is not visible by the naked eyes as hidden and placed under the cerebral hemisphere.
- The diencephalon is present in the central part of the brain as the direct extension of the brain stem.
- Epithalamus includes habenula and their interconnecting fibers the habenular commissure and the stria medullaris and the pineal gland.
- The main function of the epithalamus is carrying the information from the limbic forebrain to limbic midbrain structures.
- The epithalamus is wired by the limbic system and the basal ganglia provides a sensory network.
- Depression, schizophrenia, and sleeping disorder are mainly caused due to dysfunction in the epithalamus.
So, the correct answer is, ‘ lateral wall of diencephalon.’

Note:
- Epithalamus is also related to the secretion of melatonin by the pineal gland and also in the regulation of motor pathways.
- Epithalamus is the dorsal posterior segment of the diencephalon.
- In adults, a diencephalon appears at the upper end of the brain stem located between the cerebrum and brainstem.