LESSON 9_DIENCEPHALON: THALAMUS AND HYPOTHALAMUS Flashcards by Andre Sales

secondary brain vesicle derived from the primary brain vesicle prosencephalon; midline structure with symmetrical right and left halves

diencephalon

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cavity of the diencephalon

third ventricle

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parts of the diencephalon

3rd ventricle and the structures that form its boundaries

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primary brain vesicle of the diencephalon

prosencephalon

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boundaries of the diencephalon

extends posteriorly to where the 3rd ventricle becomes continuous with the cerebral aqueduct and anteriorly up to the interventricular foramen

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forms the inferior surface of the diencephalon

hypothalamus
optic chiasm
optic tract on each side
infundibulum
tuber cinereum
mammillary bodies

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conceals the superior surface of the diencephalon

tela choroidea and fornix

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thick bundle of fibers from hippocampus that arch posteriorly over the thalamus to join the mammillary body

fornix

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superior border of the thalamus

roof of the 3rd ventricle

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structure continuous with the roof of the 3rd ventricle

ependyma of the 3rd ventricle

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covers the roof of the 3rd ventricle superiorly

tela choroidea

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projects down from the midline into the cavity of the 3rd ventricle

choroid plexus of 3rd ventricle

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bounds the lateral surface of the diencephalon

internal capsule

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medial surface of the diencephalon

wall of the 3rd ventricle

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forms the medial surface of the diencephalon superiorly

medial surface of the thalamus

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forms the medial surface of the diencephalon inferiorly

hypothalamus

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separates the thalamus and hypothalams

hypothalamic sulcus

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superior margin of the medial surface

stria medullaris thalami

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destination of afferent fibers of the stria medullaris

habenular nucleus

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boundaries of the diencephalon

rostral: interventricular foramen
superior: roof of the 3rd ventricle
lateral: posterior limb of internal capsule
caudal: posterior commissure

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four parts of the thalamus

thalamus
subthalamus
epithalamus
hypothalamus

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largest diencephalic subdivision; large ovoid gray matter, obliquely oriented

thalamus

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relay station of all main sensory systems except the ____

thalamus

olfactory pathway

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location of the thalamus

rostral end of brainstem
between interventricular foramen and posterior commissure, extends from 3rd ventricle to medial border of posterior limb of internal capsule
dorsal to hypothalmic sulcus

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forms the posterior boundary of the interventricular foramen

anterior end of the thalamus | narrow and rounded

formed by the posterior end of the thalamus; overhangs the superior colliculus and superior brachium

pulvinar

small elevation on the under aspect of the lateral portion of the pulvinar

lateral geniculate body (LGB)

extends along the dorsomedial margin of the thalamus near the roof of the 3rd ventricle

stria medullaris thalami

structure continuous with the inferior surface of the thalamus

tegmentum of midbrain

formed by the medial surface of the thalamus

superior part of the lateral wall of the 3rd ventricle

connects the medial surface of the thalamus to the opposite thalamus

interthalamic connection (interthalamic adhesion)

covers the lateral surface of the thalamus

ependyma

forms part of the floor of the lateral ventricle

lateral surface of the thalamus

partially covers the lateral surface of the thalamus

choroid plexus of the lateral ventricle

separates the lateral surface of the thalamus from the lentiform nucleus

internal capsule

lies inferior to the thalamus and is between the thalamus and midbrain tegmentum

subthalamus

cells in the subthalamus

cranial ends of the red nuclei and the substantia nigra

tracts in the subthalamus that pass from the tegmentum to the thalamus

medial, spinal, and trigeminal lemnisci

shaped like biconcave lens; connected with corpus striatum and involved in control of muscle activity

subthalamic nuclei

structures of the epithalamus

habenular nuclei, stria medullaris thalami, habenular commissure, pineal gland

found mainly posterior to the thalamus

epithalamus

location of the habenular nucleus

habenular trigone

small group of neurons just medial to the posterior surface of the thalamus

habenular nucleus

# Habenular Nucleus afferent fibers from ____ in temporal lobe through the ____; others from ____ pass through the fornix

amygdaloid nucleus, stria medullaris thalami, hippocampus

fibers of the stria medullaris thalami that connect both nuclei with each other

habenular commissure

axons of the habenular nucleus pass to ____

* interpeduncular nucleus in the roof of the interpeduncular fossa * tectum of the midbrain * thalamus * reticular formation of midbrain

center of integration of olfactory, visceral, and somatic afferent pathways

habenular nucleus

small conical structure attached to the diencephalon that projects backwards and lies posterior to the midbrain

pineal gland (pineal body)

attaches the pineal gland to the diencephalon

pineal stalk

structure that recess found on the base of the pineal stalk is continuous with

cavity of the third ventricle

on the base of the pineal stalk

superior: contains the habenular commissure inferior: posterior commissure

two types of cells in the pineal gland

pinealocytes and glial cells

cells with club-like processes apposed to blood vessels

pinealocytes

synthesized by pinealocytes

melatonin

concretions of calcified material that accumulares with age

brain sand

# Microscopic Section of the Pineal Gland * no ____, no ____ with neurons * ____ vascularized, no ____ * activity exhibits ____ that is influenced by ____ (active in ____) * melatonin and enzymes needed for its production (____ increase at night in absence of ____) * adrenergic sympathetic fibers from ____ enter and run in association with blood vessels and pinealocytes

* no **nerve cells**, no **synaptic contact** with neurons * **richly** vascularized, no **blood brain barrier** * activity exhibits **circadian rhythm** that is influenced by **light** (active in **dark**) * melatonin and enzymes needed for its production (**serotonin N-acetyltransferase** increase at night in absence of **photic stimulation**) * adrenergic sympathetic fibers from **superior cervical ganglia** enter and run in association with blood vessels and pinealocytes

extends from optic chiasm to caudal border of mammillar bodies; below the hypothalmic sulcus on the lateral wall of the 3rd ventricle

hypothalamus

close to limbic system, thalamus, ascending and descending tracts, and hypophysis

hypothalamus

functions of the hypothalamus

* influences nearly **all physiologic activities** * controls and integrates functions of the **ANS and endocrine systems** * **homeostasis** * regulation of body temperature, body fluids, appetite and thirst, sexual behaviour, and emotions * receives inputs from the **reticular formation** (sleep/wake cycle information), **the limbic system** (emotion, fear, anger, smell), the **medulla oblongata** (blood pressure and heart rate), and the **optic system** | What does HEAL stand for?

anterior to the hypothalamus; from the optic chiasm to the lamina terminalis and anterior commissure

preoptic area

hypothalamus caudally merges with the ____

tegmentum of the midbrain

superior to the hypothalamus

thalamus

inferolateral to the hypothalamus

subthalamic region

relations of the hypothalamus (anterior to posterior)

* optic chiasm * tuber cinereum and infundibulum * mammillary bodies

flattened bundle of nerve fibers at the junction of the anterior wall and floor of the third ventricle

optic chiasm

structure that the superior surface of the optic chiasm is attached to

lamina terminalis

structure the optic chiasm is inferiorly related to

hypophysis cerebri

separates the hypophysis cerebri and the optic chiasm

diaphragma sella

# Optic Chiasm * anterolateral corners continuous with ____ * posterolateral corners continuous with ____

optic nerves, optic tracts

on the superior surface of the optic chiasm

optic recess of the 3rd ventricle

convex mass of gray matter seen on inferior surface; continuous inferiorly with the infundibulum

tuber cinereum

hollow and becomes continuous with the posterior lobe of the hypophysis cerebri

infundibulum

raised part of tuber cinereum to which is attached to the infundibulum

median eminence

structure formed by the median eminence, infundibulum, and posterior lobe (pars nervosa) of the hypophysis cerebri (pituitary gland)

neurohypophysis

two small hemispherical bodies situated side by side posterior to the tuber cinereum; possess a central core of gray matter invested by a capsule of myelinated fibers

mammillary bodies

posterior to the mammillary bodies; transmits terminal branches of the PCA

posterior perforated substance

slit-like cleft between the two thalami

3rd ventricle

anterior communication of the 3rd ventricle with the lateral ventricle

interventricular foramen of Monroe

posterior communication of the 3rd ventricle with the 4th ventricle

cerebral aqueduct

structure the posterior wall of the 3rd ventricle opens into

cerebral aqueduct

structures superior to the opening of the 3rd ventricle into the cerebral aqueduct

posterior commissure, pineal recess, and habenular commissure

forms the lateral wall of the 3rd ventricle

medial surface of the thalamus superiorly and hypothalamus inferiorly

limits the lateral wall of the 3rd ventricle superiorly

stria medullaris thalami

joins the lateral wall of the 3rd ventricle

interthalamic connection

forms the superior wall (roof) of the 3rd ventricle

layer of ependyma continuous with the lining of the ventricle

superior to the ependyma

tela choroidea of the 3rd ventricle

two layered fold of pia mater that projects downward on each side of the midline

tela choroidea of the 3rd ventricle

found within the choroid plexus of the 3rd ventricle

internal cerebral veins

structures the superior wall (roof) of the 3rd ventricle are related to

fornix and corpus callosum

components of the inferior wall (floor) of the 3rd ventricle

* optic chiasm * tuber cinereum * infundibulum * mammillary bodies

attached to the infundibulum

hypophysis

posterior to the inferior wall (floor) of the 3rd ventricle

cerebral peduncles

etymological origin of the thalamus (Greek)

"inner chamber" or "bedroom"

synaptic relay center to cerebral cortex for nearly all pathways; major sensory relay station

thalamus

origin of inputs of thalamus

motor inputs from cerebellum and basal ganglia, limbic inputs, and widespread modulatory inputs involved in behavioral arousal and sleep-wake cycles

location and appearance of thalamus

* large, egg-shaped mass of gray matter * rostral end of brainstem * two thalami * each side of 3rd ventricle

location and appearance of anterior end of thalamus

narrow and rounded, forms the posterior boundary of the interventricular foramen

location and appearance of posterior end of thalamus

expanded forming the pulvinar, which hangs over the superior colliculus

structure the inferior surface of the thalamus is continuous with

tegmentum of midbrain

location and appearance of the medial surface of the thalamus

forms part of the lateral wall of the 3rd ventricle and is usually connected to the opposite thalamus via the interthalamic connection/adhesion

thin layer of white matter that covers the superior surface of the thalamus

stratum zonale

covers the lateral surface of the thalamus

external medullary lamina

divides the thalamus into medial and lateral halves; y-shaped anteriorly

internal medullary lamina

parts of the thalamus

* anterior * lateral * medial * midline * intralaminar nuclei * reticular nuclei

receives mammillothalamic tract and reciprocal connections with cingulate gyrus and hypothalamus; closely associated with the limbic system (anterior nuclei)

anterior thalamic nuclei

function of the anterior thalamic nuclei

emotional tone and mechanisms of recent memory

receives reciprocal connections with prefrontal cortex and hypothalamic nuclei and is interconnected with all other thalamic nuclei

dorsomedial nuclei

function of dorsomedial nuclei

integration of large variety sensory information, including somatic, visceral, and olfactory information and their relation to emotion and subjective states

dorsal tier of thalamus comprises of:

* lateral dorsal nucleus * lateral posterior nucleus (pulvinar)

have connections with other thalamic nuclei and with parietal lobe, cingulate gyrus, and occipital and temporal lobes

dorsal tier of thalamus

ventral tier (craniocaudal) of thalamus comprises of:

* ventral anterior * ventral lateral * ventral posterior (VPL and VPM)

connected to reticular formation, substantia nigra, corpus striatum, premotor cortex, and other thalamic nuclei

ventral anterior nucleus

function of ventral anterior nucleus

influences activity of motor cortex

similar to VA plus major input from cerebellum and minor input from red nucleus; main projection pass to motor and premotor regions

ventral lateral nucleus

function of ventral lateral nucleus

influences motor activity

parts of the ventral posterior nucleus

VPM and VPL

receives ascending trigeminal and gustatory pathways

VPM

receives ascending sensory tracts and the medial and spinal lemnisci

VPL

thalamocortical projections pass through posterior limb of internal capsule and corona radiata to postcentral gyrus area 3, 1, and 2

ventral posterior nucleus

receives afferents from reticular formation and spinothalamic and trigeminothalamic tracts; sends efferents to other thalamic nuclei that project to cerebral cortex and fibers to corpus striatum

intralaminar nuclei

location of intralaminar nuclei

within internal medullary lamina

function of intralaminar nuclei

influence consciousness and alertness

adjacent to 3rd ventricle and in the interthalamic connections; receives afferents from reticular formation

midline nuclei

thin, extensive sheet enveloping the lateral aspect of the thalamus; afferent fibers from cerebral cortex and reticular formaton and output to other nuclei

reticular nuclei

location of reticular nuclei

between external medullar lamina and posterior limb of internal capsule

function of reticular nuclei

may be concerned with how cerebral cortex regulates thalamic activity | reticular formation = awareness and consciousness

swelling on posterior surface of the thalamus below pulvinar; auditory pathway

medial geniculate body (MGB)

afferent fibers from inferior brachium and come from inferior colliculus; receives auditory information from both ears but predominantly from ____

medial geniculate body (MGB) contralateral one

# Medial Geniculate Body (MGB) receives termination fibers of the lateral lemniscus

inferior colliculus

formed by the efferent fibers of the MGB; passes to the auditory cortex of the superior temporal gyrus

auditory radiation

swelling under the pulvinar of the thalamus; consists of 6 layers of nerve cells

lateral geniculate body (LGB)

LGB is the terminus of ____

optic tract (except those passing to the pretectal nucleus)

fibers of the LGB

axons of the ganglion cell layer of retina and come from temporal half of the ipsilateral eye and from the nasal half of the contralateral eye

function of the LGB

receives visual information from the opposite visual field

formed as the efferent fibers leave the LGB; passes to the visual cortex

visual radiation

3 main categories of thalamic nuclei

* relay nuclei * intralaminar nuclei * reticular nucleus

receives input from numerous pathways then project to the cortex; massive reciprocal connections | projections may be localized to specific region or more diffuse

relay nuclei

specific thalamic relay nuclei

lateral and anterior nuclear groups

all sensory (except olfaction) modalities, in the lateral thalamus en route to primary cortical areas

lateral nuclear group

limbic pathways to anterior cingulate cortex

anterior nuclear group

widely projecting (non-specific) thalamic relay nuclei; diffuse relays of limbic inputs and other information involved in cognitive function

mediodorsal nucleus, midline and intralaminar nuclei

major relay towards frontal association cortex

MD | mediodorsal nucleus

visual and other sensory inputs to pulvinar are relayed to large regions of the ____, ____, and ____ for behavioral orientation toward relevant stimuli

visual and other sensory inputs to pulvinar are relayed to large regions of the **parietal**, **temporal**, and **occipital association cortex** for behavioral orientation toward relevant stimuli

within the internal medullar lamina; receives inputs from many pathways and has reciprocal connections with cortex

intralaminar nuclei

main input and output of intralaminar nuclei

basal ganglia

intralaminar nuclei mainly involved in basal ganglia circuitry

caudal intralaminar nuclei (mainly centromedian nucleus)

basal ganglia, reticular activating system to cortex

rostral intralaminar nuclei

thin sheet located just lateral to the rest of the thalamus and just medial to the capsule; only nucleus of the thalamus that does not project to the cortex; receives input from other thalamic nuclei and the cortex then projects back to the thala

reticular nucleus

neurons consisting the reticular nucleus

GABAergic neurons (inhibitory)

functions of the reticular nucleus

regulates thalamic activity; inputs also come from brainstem reticular formation for maintaining consciousness

LESSON 9_DIENCEPHALON: THALAMUS AND HYPOTHALAMUS Flashcards

(150 cards)