diencephalon

(noun)

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

  • Development of the Human Brain

    • The forebrain has two major divisions: the diencephalon and the telencephalon.
    • The diencephalon is lower, containing the thalamus and hypothalamus (which together form the limbic system); the telencephalon is on top of the diencephalon and contains the cerebrum, the home of the highest-level cognitive processing in the brain.
    • The telencephalon and diencephalon give rise to the forebrain, while the metencephalon and myelencephalon give rise to the hindbrain.

  • 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 brain commisure (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 the human embryo's 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.

  • Lower-Level Structures

    • With the exception of the spinal cord, these structures are largely located within the hindbrain, diencephalon (or interbrain), and midbrain.
    • The diencephalon is the region of the embryonic vertebrate neural tube that gives rise to posterior forebrain structures.
    • In adults, the diencephalon appears at the upper end of the brain stem, situated between the cerebrum and the brain stem.
    • The diencephalon is made up of four distinct components: the thalamus, the subthalamus, the hypothalamus, and the epithalamus.

  • 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

    • The optic nerve is the second of twelve paired cranial nerves but 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.

  • Development of Vision

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

  • Thalamus

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