Hypothalamus, Thalamus, and Limbic System DSA Flashcards by Sophia Barber

What is the main function of the hypothalamus?

TAN HATS

Thirst and water balance

Adenohypohysis (ant pit)

Neurohypophysis (post pit)

Hunger

Autonomic NS

Temperature

Sexual urges

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What separates the hypothalamus and the thalamus?

hypothalamic sulcus

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What are the borders of the hypothalamus?

rostral = lamina terminalis

lateral = substantia innominata (rostral) and medial edge of posterior limb of internal capsule (caudal)

medial: inferior portion of 3rd ventricle
caudal: merges into tegmentum and PAG

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What are the divisions of the hypothalamus?

preoptic area: anterior most part, forms a continuation w/ basal forebrain

periventricular zone: adjacent to 3rd ventricle

medial zone: lateral to periventricular

lateral zone: contains medial forebrain bundle

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What is significant about the prepotic area of the hypothalamus?

medial and lateral preoptic nuclei

medial: contains neurons that make GnRH

Failure of GnRH-producing neurons to migrate from olfactory pit –> Kallmann Syndrome

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What is significant about the periventricuar zone of the hypothalamus?

adjacent to 3rd ventricle

synthesizes releasing hormones

projects via hyophyseal portal system to ant pit

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What is significant about the medial zone of the hypothalamus?

cell-rich region composed of many nuclei

supraoptic region

tuberal region

mammillary region

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What is significant about the lateral zone of the hypothalamus?

contains the medial forebrain bundle

interconnects lateral zone w/ septal nuclei and brainstem RF

lateral hypoT nucleus: feeding center

tuberal nuclei: small clusters of neurons that form the tuberoinfundibular tract –> releasing hormones to hypophysial portal sys

*Lateral injury makes you Lean*

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What are the supraoptic nuclei and what they do?

supraoptic/paraventricular nucleus: oxytocin and ADH –> Post pit

Suprachiasmatic nucleus: receives input from retina –> circadian rhythms

anterior nucleus: range of visceral/somatic fxns, temp regulation

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What are the nucleu of the tuberal region?

Ventromedial nucleus: satiety (VentroMedial injury makes you Very Massive)

dorsomedial nucleus: emotional behavior

arcuate nucleus: neurons that contain releasing hormones

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What are the nuclei of the mammillary region?

medial mammillary nucleus: primary termination pt for axons of postcommissural fornix, from subiculum of hippocampus; source of axons of mammillothalamic tract

intermediate and lateral mammillary nuclei: lateral to the medial mammillary nucleus; receives input from reticular formation via mammillary peduncle

Posterior: merges w/ PAG and assoc w/ similar emotional, cardio, and analgesic fxns

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What is the blood supply to the hypothalamus?

anteromedial grp: branches from ant communicating and A1 –> preoptic and supraoptic, septal nucei, parts of lateral area

posteromedial grp: from PCA and P1

rostral part of PCA –> tuberal region

caudal parts of PCA –> mammillary region

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What is the subiculum?

most inf part ot the hippocampus –> fornix arises from here

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What is the fornix?

arises from subiculum and hippocampus

largest single input to the hypothalamus

divides at ant commissure into precommissural bundle (hippocampus) and postcommissural bundle (subiculum)

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What are the main hypothalamic afferents?

fornix

medial forebrain bundle

amygdalohypothalamic fibers (stria terminalis and ventral amygdalofugal pathway)

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What are the ascending hypothalamic pathways?

mammillary fasciculus –> to anterior thalamic nucleus

hypothalamothalamic fibers: from lateral preoptic –> dorsomedial nucleus (thalamus) and amygdaloid nucleus

What is the mammillary fasciculus?

from medial mamillary nucleus –> mammillothalamic and mammillotegmental tracts

projects to anterior nucleus of thalamus and important part of circuit of papez

What are the hypothalamic fibers?

from lateral preoptic area –> dorsomedial nucleus (thalamus) and amygdaloid nucleus (via stria terminalis and ventral amygdalofugal path)

What are the direct links from the hypothalamus to the ANS?

hypothalamospinal and hypothalamomedullary fibers: PVN, some from lateral and posterior hypothalamic areas

hypothalamomedullary: end in solitary nucleus, vagal motor nucleus, nucleus ambiguus
hypothalamospinal: intermediolateral cell column (GVE presyn)

What are the indirect links from the hypothalamus to the ANS?

post longitudinal fasciculus: medial HT zone –> PAG

mammillotegmental tract: medial mam nucleus –> post and ant tegmental nucleus in PAG

PAG: relays info to visceral areas of brainstem

What is the supraopticohypophysial tract?

oxytocin and ADH produced in SON and PVN

transport hormones to post pit

stored in herring bodies until release into capillary plexus

What is the tuberoinfundibular tract?

input from small neurons in arcuate nucleus and periventricular zone

neurons in PVN, suprachiasmatic, tuberal, and medial preoptic nuclei contribute

axons convey releasing hormones to median eminence and infundibulum

What nucleus is responsible for circadian rhythms?

suprachiasmatic nucleus

via the subparaventricular and dorsomedial nuclei

opposes drive for sleep and indirectly controls melatonin secretion

What is the internal medullary lamina?

unmyelinated fibers

extends into thalamus and divides thalamus into groups:

anterior, medial, lateral, intralaminar, nuclear groups, midline thalamic nuclei

Where does the thalamus project to?

majority to ipsilateral cerebral cortex

What are the anterior thalamic nuclei?

large principal and 2 smaller --\> form anterior nucleus impt synaptic station in papez circuit = emotion and memory receive from mammillary nuclei via mamillothalamic tract from hippocampus via fornix output to cingulate gyrus via ant limb of internal capsule

What is Korsakoff's syndrome?

progressive degeneration of the mammillary bodies, hippocampal complex, and dorsomedial thalamic nucleus impedes retention of newly acquired memory and short term --\> long-term confabulate: combine fragmented memories into a synthesized memory of an event that never occured thiamine deficiency, typically assoc w/ chronic alcoholism

What is phantosmia?

olfactory hallucination distortion in a smell experience or the perception of a smell when no odor is presence lesion of ant/medial temporal lobe hippocampus, amygdala, or medial dorsal thalamic nuclei

What is Kluver-Bucy syndrome?

bilateral temporal lobe lesions --\> abolish amygdaloid complex visual agnosia: inability to recognize object by sight hyperorality: examine objects by mouth hypermetamorphosis: intensively explore environment or overreact to visual stimuli Placidity: don't show fear or anger hyperphagia: eating excessive amounts hypersexuality

What are signs of an uncal herniation?

dilated pupil and abnormal eye mvts w/ double vision ipsi to herniation weakness in extremities opposite to dilated pupil respiration can be affected, abnormal reflexes

What does the anterior nucleus of the hypothalamus do?

Cooling A/C = Anterior Cooling

What does the posterior nucleus of the hypothalamus do?

Hot Pot Heating controlled by Posterior

What does the VPL nucleus of the thalamus receive info from?

spinothalamic and medial lemniscus goes to primary somatosensory cortex

What does the VP**M** nucleus of the thalamus receive info from and where does it go?

Trigeminal and gustatory pathway **M**akeup goes on the **face** To primary somatosensory cortex

What does the LGN nucleus of the thalamus receive info from and where does it go?

CN II, optic chiasm, optic tract to primary visual cortex (calcarine sulcus)

What does the **M**edial geniculate nucleus of the thalamus receive info from and where does it go?

superior olive and inf colliculus of tectum hearing info --\> to auditory cortex of temporal lobe **M**edial = **M**usic

What does the **v**entral lateral nucleus of the thalamus receive info from and where does it go?

cerebellum, basal ganglia motor info --\> to motor cortex Re**v** your engine = motor ventral lateral

What makes up the Limbic System?

HAMACE Hippocampus Amygdalae Mammillary Bodies Ant Thalamic Nuclei Cingulate gyrus Entorhinal cortex

What is the limbic system responsible for?

the famous 5 F's Feeding Fleeing Fighting Feeling Fucking