diencephalon

(noun)

The region of the human brain, specifically the forebrain, that includes the thalamus, hypothalamus, epithalamus, prethalamus or subthalamus, and pretectum.

Related Terms

Examples of diencephalon in the following topics:

  • Functions of the Diencephalon

    • Distinct parts of diencephalon perform numerous vital functions, from regulating wakefulness to controlling the autonomic nervous system.
    • The diencephalon ("interbrain") is the region of the vertebrate neural tube that gives rise to posterior forebrain structures.
    • In development, the forebrain develops from the prosencephalon, the most anterior vesicle of the neural tube that later forms both the diencephalon and the telencephalon.
    • In adults, the diencephalon appears at the upper end of the brain stem, situated between the cerebrum and the brain stem.

  • Epithalamus and Pineal Gland

    • The epithalamus is a dorsal posterior segment of the diencephalon (as shown in the figure below).
    • The habenular commissure is a band of nerve fibers situated in front of the pineal gland that connects the habenular nuclei on both sides of the diencephalon.

  • Development of the Central Nervous System

    • At six weeks in human embryo development, the prosencephalon divides further into the telencephalon and diencephalon and the rhombencephalon divides into the metencephalon and myelencephalon.
    • Diencephalon elaborations include the subthalamus, hypothalamus, thalamus, and epithalamus, and its cavity forms the third ventricle.

  • Midbrain

    • Caudally (posteriorly) the mesencephalon adjoins the pons (metencephalon), and rostrally it adjoins the diencephalon (eg., thalamus, hypothalamus).
    • It does not split into other brain areas while the prosencephalon, for example, divides into the telencephalon and the diencephalon.

  • Optic (II) Nerve

    • It is considered by physiologists to be part of the central nervous system, as it is derived from an outpouching of the diencephalon during embryonic development.

  • Embryonic Development of the Brain

    • The basal plate becomes the diencephalon.
    • The diencephalon, mesencephalon, and rhombencephalon constitute the brain stem of the embryo.

  • Thalamus

    • The thalamus surrounds the third ventricle and is the main product of the embryonic diencephalon.

  • Limbic System

    • This diagram of the limbic system delineates components of the diencephalon and cerebrum.

  • Development of Vision

    • Chordamesoderm induces the anterior portion of the neural tube to form the precursors of the synapomorphic tripartite brain of vertebrates, a bulge called the diencephalon.

  • Embryonic Development

    • The prosencephalon further goes on to develop into the telencephalon (the forebrain or cerebrum) and the diencephalon (the optic vesicles and hypothalamus).