Hypothalamus
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Not to be confused with Subthalamus or Hypophthalmus.
Hypothalamus
Location of the human hypothalamus
Location of the hypothalamus (cyan) in relation to the pituitary and to the rest of the brain
Details
Part of Brain
Identifiers
Latin hypothalamus
MeSH D007031
NeuroLex ID birnlex_734
TA98 A14.1.08.401
A14.1.08.901
TA2 5714
FMA 62008
Anatomical terms of neuroanatomy
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Look up hypothalamus in Wiktionary, the free dictionary.
The hypothalamus (pl.: hypothalami; from Ancient Greek ὑπό (hupó) 'under' and θάλαμος
(thálamos) 'chamber') is a small part of the vertebrate brain that contains a number of nuclei with a
variety of functions. One of the most important functions is to link the nervous system to the
endocrine system via the pituitary gland. The hypothalamus is located below the thalamus and is
part of the limbic system.[1] It forms the basal part of the diencephalon. All vertebrate brains contain
a hypothalamus.[2] In humans, it is about the size of an almond.[3]
The hypothalamus has the function of regulating certain metabolic processes and other activities of
the autonomic nervous system. It synthesizes and secretes certain neurohormones, called releasing
hormones or hypothalamic hormones, and these in turn stimulate or inhibit the secretion of
hormones from the pituitary gland. The hypothalamus controls body temperature, hunger, important
aspects of parenting and maternal attachment behaviours, thirst,[4] fatigue, sleep, circadian
rhythms, and is important in certain social behaviors, such as sexual and aggressive behaviors.[5][6]
Structure
The hypothalamus is divided into four regions (preoptic, supraoptic, tuberal, mammillary) in a
parasagittal plane, indicating location anterior-posterior; and three zones (periventricular,
intermediate, lateral) in the coronal plane, indicating location medial-lateral.[7] Hypothalamic nuclei
are located within these specific regions and zones.[8] It is found in all vertebrate nervous systems. In
mammals, magnocellular neurosecretory cells in the paraventricular nucleus and the supraoptic
nucleus of the hypothalamus produce neurohypophysial hormones, oxytocin and vasopressin.[9]
These hormones are released into the blood in the posterior pituitary.[10] Much smaller
parvocellular neurosecretory cells, neurons of the paraventricular nucleus, release corticotropin-
releasing hormone and other hormones into the hypophyseal portal system, where these hormones
diffuse to the anterior pituitary.[citation needed]
Nuclei
The hypothalamic nuclei include the following:[11][12]
List of nuclei, their functions, and the neurotransmitters, neuropeptides, or hormones that they
utilize
Region Area NucleusFunction[13]
Anterior (supraoptic) Preoptic Preoptic nucleus
Thermoregulation
Ventrolateral preoptic nucleus Sleep
Medial Medial preoptic nucleus
Regulates the release of gonadotropic hormones from the adenohypophysis
Contains the sexually dimorphic nucleus, which releases GnRH, differential development between
sexes is based upon in utero testosterone levels
Thermoregulation[14]
Supraoptic nucleus
Vasopressin release
Oxytocin release
Paraventricular nucleus
thyrotropin-releasing hormone release
corticotropin-releasing hormone release
oxytocin release
vasopressin release
somatostatin round
arousal (wakefulness and attention)[15][16]
appetite
Anterior hypothalamic nucleus
thermoregulation
panting
sweating
thyrotropin inhibition
Suprachiasmatic nucleus
Circadian rhythms
Lateral Lateral nucleus See Lateral hypothalamus § Function – primary source of orexin neurons
that project throughout the brain and spinal cord
Middle (tuberal) Medial Dorsomedial hypothalamic nucleus
blood pressure
heart rate
GI stimulation
Ventromedial nucleus
satiety
neuroendocrine control
Arcuate nucleus
Growth hormone-releasing hormone (GHRH)
feeding
Dopamine-mediated prolactin inhibition
Lateral Lateral nucleus See Lateral hypothalamus § Function – primary source of orexin neurons
that project throughout the brain and spinal cord
Lateral tuberal nuclei
Posterior (mammillary) Medial Mammillary nuclei (part of mammillary bodies)
memory
Posterior nucleus
Increase blood pressure
pupillary dilation
shivering
vasopressin release
Lateral Lateral nucleus See Lateral hypothalamus § Function – primary source of orexin neurons
that project throughout the brain and spinal cord
Tuberomammillary nucleus[17]
arousal (wakefulness and attention)
feeding and energy balance
learning
memory
sleep
Cross-section of the monkey hypothalamus displays two of the major hypothalamic nuclei on either
side of the fluid-filled third ventricle.
Cross-section of the monkey hypothalamus displays two of the major hypothalamic nuclei on either
side of the fluid-filled third ventricle.
Hypothalamic nuclei
Hypothalamic nuclei
Hypothalamic nuclei on one side of the hypothalamus, shown in a 3-D computer reconstruction[18]
Hypothalamic nuclei on one side of the hypothalamus, shown in a 3-D computer reconstruction[18]
Connections
Further information: Lateral hypothalamus § Orexinergic projection system, and Tuberomammillary
nucleus § Histaminergic outputs
The hypothalamus is highly interconnected with other parts of the central nervous system, in
particular the brainstem and its reticular formation. As part of the limbic system, it has connections
to other limbic structures including the amygdala and septum, and is also connected with areas of
the autonomous nervous system. [citation needed]
The hypothalamus receives many inputs from the brainstem, the most notable from the nucleus of
the solitary tract, the locus coeruleus, and the ventrolateral medulla. [citation needed]
Most nerve fibres within the hypothalamus run in two ways (bidirectional).
Projections to areas caudal to the hypothalamus go through the medial forebrain bundle, the
mammillotegmental tract and the dorsal longitudinal fasciculus.
Projections to areas rostral to the hypothalamus are carried by the mammillothalamic tract, the
fornix and terminal stria.
Projections to areas of the sympathetic motor system (lateral horn spinal segments T1–L2/L3) are
carried by the hypothalamospinal tract and they activate the sympathetic motor pathway.
