Diencephalon

Diencephalon
Details
Precursor	Prosencephalon, derived from the neural tube
Part of	Human brain
Parts	Thalamus, the hypothalamus, the epithalamus and the subthalamus
Identifiers
Latin	diencephalon
MeSH	D004027
NeuroLex ID	birnlex_1503
TA	A14.1.03.007; A14.1.08.001
TH	H3.11.03.5.00001
FMA	62001
	Anatomical terms of neuroanatomy

The diencephalon is a division of the forebrain (embryonic prosencephalon), and is situated between the telencephalon and the midbrain (embryonic mesencephalon). It consists of structures that are on either side of the third ventricle, including the thalamus, the hypothalamus, the epithalamus and the subthalamus.

The diencephalon is one of the main vesicles of the brain formed during embryogenesis. During the third week of development a neural tube is created from the ectoderm, one of the three primary germ layers. The tube forms three main vesicles during the third week of development: the prosencephalon, the mesencephalon and the rhombencephalon. The prosencephalon gradually divides into the telencephalon and the diencephalon.

Structure

The diencephalon consists of the following structures:

Thalamus
Hypothalamus including the posterior pituitary
Epithalamus which consists of:
- Anterior and Posterior Paraventricular nuclei
- Medial and lateral habenular nuclei
- Stria medullaris thalami
- Posterior commissure
- Pineal body
Subthalamus

Attachments

The optic nerve (CNII) attaches to the diencephalon. The optic nerve is a sensory (afferent) nerve responsible for vision; it runs from the eye through the optic canal in the skull and attaches to the diencephalon. The retina itself is derived from the optic cup, a part of the embryonic diencephalon.

Function

The diencephalon is the region of the embryonic vertebrate neural tube that gives rise to anterior forebrain structures including the thalamus, hypothalamus, posterior portion of the pituitary gland, and the pineal gland. The diencephalon encloses a cavity called the third ventricle. The thalamus serves as a relay centre for sensory and motor impulses between the spinal cord and medulla oblongata, and the cerebrum. It recognizes sensory impulses of heat, cold, pain, pressure etc. The floor of the third ventricle is called the hypothalamus. It has control centres for control of eye movement and hearing responses.

Additional images

Diagram depicting the main subdivisions of the embryonic vertebrate brain. These regions will later differentiate into forebrain, midbrain and hindbrain structures.
Reconstruction of peripheral nerves of a human embryo of 10.2 mm. (Label for Diencephalon is at left.)

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References

This article incorporates text in the public domain from page 807 of the 20th edition of Gray's Anatomy (1918)

External links

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