DiencephalonDiencephalonDiencephalonDiencephalon

HypothalamusHypothalamusHypothalamusHypothalamus

General informationGeneral information

Part ofPart of diencephalondiencephalon

Weighs aboutWeighs about 4 4 gramsgrams

The whole brain weighsThe whole brain weighs 1 400 1 400 gramsgrams

Occupies the bottom and infero-lateral wallsOccupies the bottom and infero-lateral walls of of

the III ventriclethe III ventricle

TopographyTopography

In the center ofIn the center of the the limbic systemlimbic system. .

At the crossing ofAt the crossing of numerous nerve pathwaysnumerous nerve pathways. .

Surrounded by theSurrounded by the circle of Williscircle of Willis..

BoundariesBoundaries

AnteriorAnterior Lamina terminalisLamina terminalis

PosteriorPosterior CorporaCorpora mammillar mammillariaia

DorsalDorsal Sulcus hSulcus hypothalamicypothalamicusus

MedialMedial ІІІ стомахчеІІІ стомахче

LateralLateral SubthalamusSubthalamus && capsula internacapsula interna

VentralVentral Chiasma opticumChiasma opticum, tuber , tuber

cinereum, cinereum, corpora corpora mammillarmammillariaia

&& neurohypophysis neurohypophysis

Chiasma opticumChiasma opticum

InfundibulumInfundibulum

Tuber cinereumTuber cinereum

Corpus mamillare Corpus mamillare

Tractus opticusTractus opticus

AnatomyAnatomy

OrganizationOrganization

Composed of lateral and medial zones divided byComposed of lateral and medial zones divided by

fornixfornix. .

Nuclei of the lateral zoneNuclei of the lateral zone concerned with feeding concerned with feeding

((center of hungercenter of hunger) ) and drinkingand drinking ( (center of thirstcenter of thirst). ).

Nuclei of the medial zone grouped inNuclei of the medial zone grouped in 3 3 regionsregions::

regio anteriorregio anterior, , tuberalistuberalis and and posteriorposterior. .

ХХипоталамични ипоталамични области и ядраобласти и ядра

Латерална областЛатерална област Nucl. preopticus lateralisNucl. preopticus lateralis Nucl. hypothalamicus lateralisNucl. hypothalamicus lateralis

Медиална областМедиална област Regio preopticaRegio preoptica

Nucl. preopticus medialisNucl. preopticus medialis Полово диморфично ядроПолово диморфично ядро

Regio supraopticaRegio supraoptica Nucl. suprachiasmatisNucl. suprachiasmatis Nucl. anteriorNucl. anterior Nucl. paraventricularisNucl. paraventricularis Nnucl. supraopticusNnucl. supraopticus

Regio tuberalisRegio tuberalis Nucl. dorsomedialisNucl. dorsomedialis Nucl. ventromedialisNucl. ventromedialis Nucl arcuatusNucl arcuatus

Regio mamillarisRegio mamillaris Nucll. mamillaresNucll. mamillares Nucl. posteriorNucl. posterior

Crossed byCrossed by fasciculus prosencephalicus medialisfasciculus prosencephalicus medialis

Contains two nucleiContains two nuclei::

1. Nucleus preopticus lateralis1. Nucleus preopticus lateralis

2. Nucleus hypothalamicus lateralis2. Nucleus hypothalamicus lateralis

- - when stimulated feeling of hungerwhen stimulated feeling of hunger

- - when destroyedwhen destroyed anorexia nervosa and fastanorexia nervosa and fast

Lateral zoneLateral zone

Nucleus preopticus Control of parasympathetic function

Nucleus supraopticus Synthesis and secretion of vasopressin. Damage causes diabetes insipidus.

Nucleus suprachiasmaticus

Fibers from the retina; fibers to the pineal body. Controls circadian rhythms.

Nucleus anterior Controls temperature and sexual behavior.

Nucleus paraventricularis Synthesis and secretion of oxytocin (milk secretion & uterine contraction). Controls food intake

Regio anteriorRegio anterior

HypothalamusHypothalamus

Nucleus dorsomedialisNucleus dorsomedialis

- - center of hungercenter of hunger

- - on stimulationon stimulation rage, crueltyrage, cruelty

Nucleus ventromedialisNucleus ventromedialis

- - center of satietycenter of satiety

- - on stimulation depression of apetiteon stimulation depression of apetite

Nucleus arcuatusNucleus arcuatus

- periventricular in- periventricular in tuber cinereumtuber cinereum

- - secretessecretes releasing-factorsreleasing-factors

- - dopaminergic neuronsdopaminergic neurons, , inhibit release ofinhibit release of prolactinprolactin

Regio tuberalisRegio tuberalis

Nucleus mamillarisNucleus mamillaris

- - impulses fromimpulses from hippocampal formationhippocampal formation viavia fornix fornix

- - impulses fromimpulses from tegmental nucleitegmental nuclei, , nuclei raphaenuclei raphae via via pedunculus mamillarispedunculus mamillaris

- - projections toprojections to nucleus anterior thalaminucleus anterior thalami via via tractus mamillothalamicustractus mamillothalamicus

Nucleus posteriorNucleus posterior

- - controlscontrols thermoregulationthermoregulation (съхранение и образуване на топлина) (съхранение и образуване на топлина)

- - damage causesdamage causes poikilothermiapoikilothermia – – inability ofinability of thermoregulationthermoregulation

Regio posteriorRegio posterior

ConnectionsConnections

ConnectionsConnections

ExtensiveExtensive andand complexcomplex, , can be summarized incan be summarized in 3 3

categoriescategories: :

Connections with theConnections with the limbic systemlimbic system

Connections with theConnections with the pituitary glandpituitary gland

Connections withConnections with somatic and visceral nucleisomatic and visceral nuclei

1)1) Fasciculus prosencephalicus medialisFasciculus prosencephalicus medialis: : visceral functionvisceral function

2) 2) Tractus sTractus supraopticohypophysialupraopticohypophysialisis: : neurosecretionneurosecretion

3) 3) Tractus tTractus tuberoinfundibularuberoinfundibularisis: : liberinsliberins && statinsstatins

4) 4) Afferents fromAfferents from corpora mamillariacorpora mamillaria: : visceral functionvisceral function

5) 5) Efferents toEfferents to brainstem & spinal cordbrainstem & spinal cord: : autonomous autonomous

functionfunction

ConnectionsConnections

AfferentsAfferents

- - nucleus tractnucleus tractusus solitarsolitarii ii – – visceral information viavisceral information via vagus. vagus.

- - formatioformatio reticularreticularis is ––various information from spinal cordvarious information from spinal cord. .

- - retinaretina – – to to nucl. suprachiasmatic nucl. suprachiasmaticusus. . Circadian rhythmCircadian rhythm. .

- - circumventricular organscircumventricular organs – – lacks blood-brain bareerlacks blood-brain bareer. .

Control of substances isolated from the CNS, e.g., toxinsControl of substances isolated from the CNS, e.g., toxins. .

- - limbic and olfactory systemlimbic and olfactory system – –controls behavior reactionscontrols behavior reactions..

-- intrinsic intrinsic receptorsreceptors, , monitor temperature and water monitor temperature and water

balancebalance. .

Main afferentsMain afferentsFrom most parts of brainFrom most parts of brain. . Most pathways are non-myelinated and smallMost pathways are non-myelinated and small. .

Fasciculus prosencephalicus medialisFasciculus prosencephalicus medialis FromFrom area septalarea septalisis & & area olfactorarea olfactoriaia lateral lateralisis to hypothalamic to hypothalamic nuclei.nuclei.IntegratesIntegrates olfactionolfaction withwith emotionsemotions andand feedingfeeding. .   Stria Stria tterminaliserminalis FromFrom corpus amygdaloideumcorpus amygdaloideum and and area septalisarea septalis toto regio regio preopticpreopticaa andand nuclei hypothalamici anterioresnuclei hypothalamici anteriores. . Controls physiological response toControls physiological response to emotions and sexual emotions and sexual arousalarousal. .   FornixFornix FromFrom formatioformatio hippocampalhippocampalisis toto corporacorpora mammillar mammillariaia. . IntegratesIntegrates memorymemory, , emotionsemotions andand visceral reactionsvisceral reactions. .

Main efferentsMain efferents

Fasciculus Fasciculus mmammillothalamicammillothalamicusus FromFrom nucleinuclei mamillaresmamillares to to nucleus anterior nucleus anterior of of

thalamusthalamus. . Creating and coding Creating and coding memory tracesmemory traces. .

  

Hypothalamo-reticular pathwayHypothalamo-reticular pathway Connects the hypothalamus withConnects the hypothalamus with parasympathetic parasympathetic

and sympathetic nucleiand sympathetic nuclei. .

EfferentsEfferents: : To autonomous nervous systemTo autonomous nervous systemmedulla: а) medulla: а) parasympathetic nucleus ofparasympathetic nucleus of n. vagusn. vagusб) б) cells projecting tocells projecting to sympathetic nucleisympathetic nuclei in the spinal cord.in the spinal cord.Control ofControl of heart rateheart rate, , vasoconstrictionvasoconstriction, , digestiondigestion, , sweating sweating etc.etc.. .

Endocrine signals toEndocrine signals to//throughthrough pituitary glandpituitary gland а) а) axons to neurohypophysisaxons to neurohypophysis to releaseto release oxitocinoxitocin && vasopressinvasopressin; ; б) releasing factors б) releasing factors into the vessels ofinto the vessels of adenohypophysisadenohypophysis. .

HypothHypoth can control anycan control any endocrine glandendocrine gland, , changechange blood blood pressurepressure (vasopressin (vasopressin and vasoconstriction and vasoconstriction), ), body body temperaturetemperature, , metabolismmetabolism (TSH) (TSH) and epinephrine leveland epinephrine level (ACTH). (ACTH).

Blood pressureBlood pressure, , temperaturetemperature, , waterwater and electrolyte and electrolyte

balancebalance, , weightweight are maintained within optimal valuesare maintained within optimal values..

Hypothalamus = HomeostasisHypothalamus = Homeostasis

AutonomousAutonomous, , endocrineendocrine, , emotionalemotional andand somatic somatic

functionsfunctions

ServesServes three basic systemsthree basic systems::

– Autonomic nervous systemAutonomic nervous system

– Endocrine systemEndocrine system

– Lymbic systemLymbic system

MaintainsMaintains homeostasishomeostasis of the bodyof the body

Controls

FunctionFunction1. 1. Autonomous controlAutonomous control - - anterior regionanterior region stimulates parasympathetic functionstimulates parasympathetic function

- - posterior regionposterior region stimulates sympathetic functionstimulates sympathetic function

2. 2. ThermoregulationThermoregulation

- - anterior regionanterior region maintainsmaintains bogy temperaturebogy temperature

- - posterior regionposterior region stimulatesstimulates production and preservingproduction and preserving heatheat

3. 3. Maintaining water balanceMaintaining water balance

а. а. Nucleus ventromedialisNucleus ventromedialis – center of – center of satietysatiety

б.б. Nucleus hypothalamicus lateralis Nucleus hypothalamicus lateralis – center of – center of hungerhunger

4. 4. Liberins and statinsLiberins and statins

- produced from - produced from nucleus arcuatusnucleus arcuatus

- - transported to thetransported to the portal system ofportal system of adenohypophysisadenohypophysis

- - control hormon production in the adenohypophysiscontrol hormon production in the adenohypophysis

Functional characteristicsFunctional characteristics

SubthalamusSubthalamus

General characteristicsGeneral characteristics

Vaguely delineated area betweenVaguely delineated area between midbrainmidbrain, , thalamusthalamus, ,

hypothalamushypothalamus, , capsula internacapsula interna andand ІІІ ІІІ ventricleventricle..

Contains fibers andContains fibers and nuclear structuresnuclear structures - - zona incerta,zona incerta, nucleus nucleus

subthalamicus, Forel fieldssubthalamicus, Forel fields, , nuclei reticularesnuclei reticulares

Connected mainly with somatomotor functionsConnected mainly with somatomotor functions

http://www.bartleby.com/107/189.html

Nuclear structuresNuclear structures

Nucleus subthalamicus (Luys)Nucleus subthalamicus (Luys)

– Well definedWell defined lying onlying on capsula internacapsula interna

– Rostral penetration ofRostral penetration of sustantia nigrasustantia nigra

– Connected bilaterally withConnected bilaterally with globus pallidusglobus pallidus Nuclei reticularesNuclei reticulares

– Small groupsSmall groups and extensionsand extensions of cellsof cells Zona incerta - Zona incerta - continuation of continuation of nucleus reticularis thalaminucleus reticularis thalami FieldsFields H ofH of ForelForel ( (prerubralprerubral))::

– H1 ofH1 of Forel - Forel - betweenbetween thalamus andthalamus and zona insertazona inserta

– H2 ofH2 of ForelForel - between - between nucl. subthalamicus andnucl. subthalamicus and zona zona insertainserta

A. Fasciculus thalamicus (inA. Fasciculus thalamicus (in H1 field ofH1 field of Forel)Forel)1. Lemniscus medialis1. Lemniscus medialis2. 2. Tractus dentatothalamicusTractus dentatothalamicus3. Tractus pallidothalamicus3. Tractus pallidothalamicus

44.. Bundle ofBundle of reticular fibersreticular fibers connecting brainstem with connecting brainstem with diencephalondiencephalon

BB.. Fasciculus lenticularis Fasciculus lenticularis (in(in H2 field ofH2 field of Forel)Forel)

- - Pallidothalamic fibersPallidothalamic fibers throughthrough capsula internacapsula interna

CC.. Ansa lenticularis Ansa lenticularis

- - Fibers fromFibers from globus pallidus (mainly pallidothalamic)globus pallidus (mainly pallidothalamic) beneath capsula internabeneath capsula interna

DD. . Fasciculus subthalamicusFasciculus subthalamicus – bidirectional – bidirectional fibers betweenfibers between globus pallidus and nucleus subthalamicusglobus pallidus and nucleus subthalamicus

FibersFibers