Diencephalon Flashcards
Parts of diencephalon
Hypothalamus, thalamus, geniculate bodies (medial & lateral), subthalamus, epithalamus
laminae medullares in thalamus
plates of white matter that separate thalamic nuclei
Groups of nuclei in thalamus
anterior:
- nuclei anteriores thalami
medial-dorsal:
- nucleus mediodorsalis
lateral:
- nucleus ventralis anterior, nucleus ventralis lateralis
- nucleus ventralis posterolateralis, nucleus ventralis posteromedialis
- nuclei pulvinares
- corpus geniculatum laterale
- corpus geniculatum mediale
Nuclei anteriores thalami
afferent fibers from corpus mamillare (tractus mamillo-thalamicus)
efferent fibers into gyrus cinguli
connects different parts of limbic system
regulation of emotions and memory
Nucleus mediodorsalis (MD)
afferent fibers from corpus amygdaloideum
efferent fibers to prefrontal cortex (part of limbic system)
damage causes memory loss, decreases intellectual capacity
Lateral thalamic nuclei
nucleus ventralis anterior & nucleus ventralis posterior, VA & VL
nucleus ventralis posterolateralis & nucleus ventralis posteromedialis, VPL & VPM
nuclei pulvinares
corpus geniculatum laterale
corpus geniculatum mediale
Thalamus: nucleus ventralis anterior (VA) & nucleus ventralis posterior (VP) of thalamus
afferent fibers from subcortical motor centers (corpus pallidus, substantia nigra, cerebellum)
efferent fibers to premotor and motor cortex
initiation of movement, control of muscle tone
part of extrapyramidal system
subcortical motor centers
corpus pallidus, substantia nigra, cerebellum
Thalamus: nucleus ventralis posterolateralis (VPL) & nucleus medialis posteromedialis (VPM)
recieve conscious sensory impulses (touch, pain, temperature, taste)
Nuclei pulvinares
afferent fibers from corpus geniculatum laterale (et mediale?), colliculus superior and visual association cortical areas
efferent fibers back to visual association cortical areas
regulation of visual attention
Corpus geniculatum laterale
afferents via tractus opticus
efferents to primary visual cortex (Brodmann area 17)
interneurons of visual pathway
subcortical visual center
Corpus geniculatum mediale
afferents from lemniscus lateralis
efferents to primary auditory cortex (Brodmann areas 41,42)
interneurons of hearing pathway
subcortical auditory center
Subthalamus - structure and contents
Below thalamus, separated by sulcus hypothalamicus
Contains nucleus subthalamicus
Nucleus subthalamicus
part of extrapyramidal system (controls voluntary movement of limbs)
part of basal nuclei
dorsally to substantia nigra
interconnected with globus pallidus
Epithalamus
pineal gland & additional structures:
habenula
trigonum habelunare - in the middle of both thalamus
commissura habelunarum - formed by striae medullares running between superior and medial surfaces of thalamus and partly crossing to the other side
Pineal gland
secretes seratonin, norepinephrine and melatonin (makes melatonin from seratonin)
information from visual pathway influences intensity of melatonin synthesis, biological rhythm regulator/cicardian clock
influences development of telencephalon, intellectual ability, proportional development of the body and inhibits maturation of genitals before puberty, responsible for skin pigmentation
subcortical visual centers
pulvinar, corpus geniculatum laterale, colliculus superior
Hypothalamus - contents
Mamillary bodies (corpus mamillare) : subcortical center of smell
Neurohypophysis : regulates action of all endocrine organs with adenohypophysis (secretes hormones produced in hypothalamus aka oxytocin & ADH), lies in fossa hypophysialis (sella turcica), connected to base of brain via infundibulum
Optic chiasma : crossed medial and uncrossed lateral fibers of CN2 (optic nerve)
Optic tract : fibers of optic nerve from both eyes, terminates in subcortical visual centers
Tuber cinereum : tuberal nuclei, secrete histamine in brain, helps to regulate cicardian cycle
Hypothalamus - functions
Highest center of autonomic nervous system
Links nervous system to endocrine system via pituitary gland secretes neurohormones (hypothalamic-releasing hormones) that stimulate or inhibit secretion from pituitary (adenohypophysis)
Hypothalamus controls body temperature, hunger, thirst, emotions (? at least anger), cicardian cycle etc.
Tractus hypothalamicospinalis
axons of hypothalamic nuclei that pass to PARASYMPATHETIC NUCLEI OF BRAIN & SC –> provide control of hypothalamus over autonomical functions
ventriculus tertius - anterior border
Lamina terminalis: thin plate from optic chiasma to rostrum corporis callosi
Columnae fornicis
Comissura cerebri anterior: in front of columnae fornicis, bundle of fibers connecting olfactory bulb and olfactory cortex
Recessus supraopticus: lower part of anterior wall
ventriculus tertius - posterior border
epiphysis
commissura habenularum
commissura cerebri posterior: band of nerve fibers beneath pineal gland, connecting both sides of midbrain
ventriculus tertius - superior border
tela choroidea: duplication of pia mater encephali
plexus choroideus: produces CSF
ventriculus tertius - communications
aqueductus cerebri - with 4th ventricle posteriorly
foramina interventricularia (2) - with lateral ventricles anteriorly foramen interventriculare is bordered by columnae fornicis (anterior) and tuberculum anterius thalami (posterior)
