Subthalamus
Encyclopedia
The subthalamus is a part of the diencephalon
. Its major part is the subthalamic nucleus
. Functionally, it also encompasses the globus pallidus
, which is topographically part of the telencephalon
.
, but is separated by white matter
fibres mainly from the internal capsule
. Caudally, the subthalamus or prethalamus is separated from the thalamus by the zona limitans intrathalamica
. Other nuclei
of the subthalamus are the zona incerta
, thalamic reticular nucleus, and the fields of Forel
.
Post-natally the subthalamus lies beneath the thalamus
, hence 'sub' (meaning below) 'thalamus'. It also lies dorsolateral to the hypothalamus
.
(output) connections to the striatum
(caudate nucleus
and putamen
) in the telencephalon
, 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
(input) connections from the substantia nigra and striatum.
Diencephalon
The diencephalon is the region of the vertebrate neural tube which gives rise to posterior forebrain structures. In development, the forebrain develops from the prosencephalon, the most anterior vesicle of the neural tube which later forms both the diencephalon and the...
. Its major part is the subthalamic nucleus
Subthalamic nucleus
The subthalamic nucleus is a small lens-shaped nucleus in the brain where it is, from a functional point of view, part of the basal ganglia system. Anatomically, it is the major part of subthalamus. As suggested by its name, the subthalamic nucleus is located ventral to the thalamus. It is also...
. Functionally, it also encompasses the globus pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...
, which is topographically part of the telencephalon
Telencephalon
The cerebrum or telencephalon, together with the diencephalon, constitutes the forebrain. The cerebrum is the most anterior region of the vertebrate central nervous system. Telencephalon refers to the embryonic structure, from which the mature cerebrum develops...
.
Anatomy
During development the subthalamus is continuous with the hypothalamusHypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
, but is separated by white matter
White matter
White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...
fibres mainly from the internal capsule
Internal capsule
The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons....
. Caudally, the subthalamus or prethalamus is separated from the thalamus by the zona limitans intrathalamica
Zona limitans intrathalamica
The zona limitans intrathalamica is a lineage-restriction compartment and primary developmental boundary in the vertebrate forebrain that serves as a signaling center and a restrictive border between the thalamus and the prethalamus...
. Other nuclei
Nucleus (neuroanatomy)
In neuroanatomy, a nucleus is a brain structure consisting of a relatively compact cluster of neurons. It is one of the two most common forms of nerve cell organization, the other being layered structures such as the cerebral cortex or cerebellar cortex. In anatomical sections, a nucleus shows up...
of the subthalamus are the zona incerta
Zona incerta
The zona incerta is a horizontally elongated region of gray matter cells in the subthalamus below the thalamus. Its connections project extensively over the brain from the cerebral cortex down into the spinal cord....
, thalamic reticular nucleus, and the fields of Forel
Fields of forel
Fields of Forel is an area in a deep part of the brain known as the diencephalon. It is below the thalamus and consists of three defined, white matter areas of the subthalamus. These three regions are named "H fields" ....
.
Post-natally the subthalamus lies beneath the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, hence 'sub' (meaning below) 'thalamus'. It also lies dorsolateral to the hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
.
Relations
The subthalamus develops efferentEfferent nerve
In the nervous system, efferent nerves, otherwise known as motor or effector neurons, carry nerve impulses away from the central nervous system to effectors such as muscles or glands...
(output) connections to the striatum
Striatum
The striatum, also known as the neostriatum or striate nucleus, is a subcortical part of the forebrain. It is the major input station of the basal ganglia system. The striatum, in turn, gets input from the cerebral cortex...
(caudate nucleus
Caudate nucleus
The caudate nucleus is a nucleus located within the basal ganglia of the brains of many animal species. The caudate nucleus is an important part of the brain's learning and memory system.-Anatomy:...
and putamen
Putamen
The putamen is a round structure located at the base of the forebrain . The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that comprises the basal ganglia. Through various pathways, the putamen is connected to the substantia nigra and globus pallidus...
) in the telencephalon
Telencephalon
The cerebrum or telencephalon, together with the diencephalon, constitutes the forebrain. The cerebrum is the most anterior region of the vertebrate central nervous system. Telencephalon refers to the embryonic structure, from which the mature cerebrum develops...
, to the dorsal thalamus (medial and lateral nuclear groups) in the diencephalon, and to the red nucleus
Red nucleus
The red nucleus is a structure in the rostral midbrain involved in motor coordination. It comprises a caudal magnocellular and a rostral parvocellular part.-Function:...
and substantia nigra
Substantia nigra
The substantia nigra is a brain structure located in the mesencephalon that plays an important role in reward, addiction, and movement. Substantia nigra is Latin for "black substance", as parts of the substantia nigra appear darker than neighboring areas due to high levels of melanin in...
in the mesencephalon
Mesencephalon
The midbrain or mesencephalon is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal , and temperature regulation....
. It receives afferent
Afferent nerve
In the nervous system, afferent neurons , carry nerve impulses from receptors or sense organs towards the central nervous system. This term can also be used to describe relative connections between structures. Afferent neurons communicate with specialized interneurons...
(input) connections from the substantia nigra and striatum.