Question

Epithalamus is the
A. Roof of the diencephalon
B. A dorsal segment of the diencephalon
C. Dorsal sides of optic lobes
D. Floor of the diencephalon

Answer 1

Hint: Two main divisions of forebrain include diencephalon also called prosencephalon and cerebrum is known as telencephalon. Diencephalon consists of thalamus, hypothalamus, epithalamus and subthalamus. Epithalamus consists of the habenula, habenular commissure, stria medullaris and pineal gland

Complete answer:
The brain and spinal cord comprise the central nervous system. The brain is divided into the hindbrain, midbrain and forebrain. Forebrain has two parts namely diencephalon and cerebrum. Diencephalon is also called vertebrate neural tube which gives rise to forebrain structures. Diencephalon is hidden under the cerebral hemisphere and is not visible to the naked eye. Diencephalon is the part of the forebrain which is present between telencephalon and midbrain and is the central part of the brain. Diencephalon comprises thalamus, epithalamus and subthalamus. Epithalamus is the dorsal or posterior segment of the diencephalon. Forebrain comprises thalamus, hypothalamus, diencephalon and pituitary gland. Epithalamus is the roof of the diencephalon and the floor of the diencephalon consists of the optic chiasm, infundibulum and tuber cinereum.
Functions of epithalamus are:
i. The connecting point for dorsal diencephalic conduction connect other parts of the the the brain to the limbic system
ii. It is involved in melatonin secretion.
iii. It controls pituitary hormone secretions.
iv. Regulation of motor pathways and emotions are also controlled by the epithalamus.
Hence, the correct answer is option (A).

Note: Diencephalon is the part of the forebrain present between telencephalon. The midbrain consists of the thalamus. Epithalamus connects the brain to the limbic system and any dysfunction in it causes sleeping disorders.