The subthalamus or prethalamus is a part of the
diencephalon
The diencephalon (or interbrain) is a division of the forebrain (embryonic ''prosencephalon''). It is situated between the telencephalon and the midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is asso ...
.
Its most prominent structure is the
subthalamic nucleus. The subthalamus connects to the
globus pallidus, a
basal nucleus of the
telencephalon
The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb ...
.
Structure
The subthalamus is located
ventral to the
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direction ...
,
medial
Medial may refer to:
Mathematics
* Medial magma, a mathematical identity in algebra Geometry
* Medial axis, in geometry the set of all points having more than one closest point on an object's boundary
* Medial graph, another graph that re ...
to the
internal capsule and
lateral to the
hypothalamus. It is a region formed by several
grey matter nuclei and their associated
white matter
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distributi ...
structures, namely:
*The
subthalamic nucleus, whose neurons contain
glutamate and have excitatory effects over neurons of
globus pallidus and
substantia nigra
*
Zona incerta
The zona incerta (ZI) is a horizontally elongated region of gray matter in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord.
Its function is unknown, thoug ...
, located between
fields of Forel H
1 and H
2. It is continuous with the
thalamic reticular nucleus and receives input from the
precentral cortex.
*
Subthalamic fasciculus
The subthalamic fasciculus is a bi-directional neural tract that connects the subthalamic nucleus and the globus pallidus
The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical structure of the brain. It cons ...
, formed by fibers that connect the globus pallidus with the subthalamic nucleus
*
Fields of Forel
*
Ansa lenticularis
The ansa lenticularis (''ansa lentiformis'' in older texts) is a part of the brain, making up the superior layer of the substantia innominata. Its fibers, derived from the medullary lamina of the lentiform nucleus, pass medially to end in the thal ...
During development the subthalamus is continuous with the
hypothalamus, but is separated by
white matter
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distributi ...
fibres mainly from the
internal capsule. Caudally, the subthalamus or prethalamus is separated from the thalamus by the
zona limitans intrathalamica.
Postnatally, the subthalamus lies beneath the
thalamus
The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all direction ...
, hence 'sub' (meaning below) 'thalamus'. It also lies dorsolateral to the
hypothalamus.
Connections
The subthalamus develops
efferent (output) connections to the
striatum (
caudate nucleus and
putamen) in the
telencephalon
The cerebrum, telencephalon or endbrain is the largest part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb ...
, to the dorsal thalamus (medial and lateral nuclear groups) in the diencephalon, and to the
red nucleus and
substantia nigra in the
mesencephalon. It receives
afferent
Afferent may refer to:
Anatomical structures
Meaning "conveying towards a center":
* Afferent arterioles, blood vessels that supply the nephrons
* Afferent lymphatic vessels, lymph vessels that carry lymph to a lymph node
* Afferent nerve fiber ...
(input) connections from the substantia nigra and striatum.
See also
*
Subthalamic nucleus
*
Zona incerta
The zona incerta (ZI) is a horizontally elongated region of gray matter in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord.
Its function is unknown, thoug ...
References
External links
* https://web.archive.org/web/20080504165606/http://isc.temple.edu/neuroanatomy/lab/atlas/pdhn/
{{Authority control
Basal ganglia