L22-23: Brain Evolution & General Structure Flashcards
list major components of diencephalon
epithalamus
thalamus
hypothalamus
components of epithalamus
pineal body
parapineal body
choroid plexus
habenulae
calcification accrues w/ maturity
habenular nuclei
emotional and visceral responses to odor
projects to septal nuclei in thalamus via stria medullaris thalami
pineal body
involved in emotional and visceral responses to odors
projects to septal nuclei
secretes melatonin
thalamus landmarks
separated from hypothalamus by hypothalamic sulcus
commissures:
- -habenular - above pineal recess
- -posterior - below pineal recess
functions of thalamus
- relays all sensory info except smell to cerebral cortex
- provides crude awareness
- initial ANS response to intense pain
- roles in arousal, alerting, complex reflex mvts
sensory relay nuclei in thalamus
medial geniculate body
- -auditory
- -projects to primary auditory cortex in temporal lobe
lateral geniculate body
- -visual
- -projects to primary visual cortex in occipital cortex
ventral posterior nuclei in thalamus
general sensations and taste
thalamus – motor relay nuclei
ventral lateral
–voluntary motor
ventral anterior
–voluntary motor, arousal
subthalamic
thalamus reticular nuclei
modify neuronal activity in the thalamus
may be involved in regulating sleep-wake cycle and level of awareness
thalamus – anterior nuclei
concerned w/ emotions and memory
receives input from:
hippocampus, mamillary bodies
thalamus - white matter
internal capsule
stratum zonale
external medullary lamina
internal medullary lamina
functions of hypothalamus
- controls/integrates ANS
- raise/lower bp and HR
- produce ACH, oxytocin
- rage, aggression
- norm body temp
- reg food intake
- sexual center
list nuclei of hypothalamus
mammillary bodies supraoptic nuclei suprachiasmatic nuclei ant nuclei paraventricular med division paraventricular interm magnocellular division paraventricular lat div medial preoptic area tuberal level
mammillary bodies
involved in olfactory reflexes and emotional response to odors
relay stations for olfactory neurons to inf colliculi
supraoptic nuclei
send projections that release neurohormones into capillaries in post pit
- -oxytocin
- -vasopressin
suprachiasmatic nuclei
above optic chiasma
master biologic clock
anterior nuclei of hypothalamus
caudal continuation of medial preoptic area
paraventricular medial division
secretes releasing or inhibiting hormone into portal system
- -corticotropin releasing factor
- -thyroxine releasing factor
- -somatostatin
- -dopamine
paraventricular intermediate magnocellular division
sends projections to the post pit that releases oxytocin and vasopressin
paraventricular lateral division
receives input from:
brainstem nuclei
hypothalamic nuclei
limbic system
projects to sympathetic structures
medial preoptic area
larger in males
cells that release gonadotropin releasing factors to portal sys
involved in temp reg
tuberal level
might be involved in feeding and pleasure
components of telencephalon
cerebrum
olfactory tract/bulbs
striatum
lamina terminalis
define cerebrum
paired right and left hemispheres, each with a ventricle
define striatum
refers to collection of basal nuclei that develop in the floor of the telencephalon
lamina terminalis
original cephalic boundary of the neural tube
separates the 2 lat ventricles
primitive roof of the telencephalon
= pallium
lacks a cortex
serves as primitive sensory and association area
receives info from olfactory apparatus
what is a cortex?
consists of multiple layers of gray matter
built from the bottom up
sits on top pallium
sulci and gyri increase surface area
neocortex divisions
frontal parietal temporal insula occipital
occipital lobe
integrates eye focusing mvts
correlates visual images w/ visual memory
involved in conscious perception of vision
separated from parietal lobe by parietooccipital sulcus
parietal lobe
Somatesthetic interpretation
–postcentral gyrus
understanding speech
- -auditory assoc cortex
- -wernicke’s area
formulating words to express thoughts and emotions
frontal lobe
voluntary motor control --precentral gyrus motivation, aggression, mood, personality, cognitive processes verbal communication --broca's area
temporal lobe
receives/interprets olfactory and auditory senses
responsible for storage of memory related to auditory/visual experiences
insula
not seen from surface
memory
psychic cortex
–highest levels of brain function = abstract thought, judgement
internal capsule and corpus callosum
- connects cortex w/ brainstem
2. connects neocortex of 2 hemispheres
putamen
large subconscious mvts of skeletal muscles
globus pallidus
regulates muscle tone
globus pallidus + putamen = ?
lentiform nucleus
substantia nigra – 2 divisions and characteristics
- dorsal pars compacta
- –melanin containing neurons
- – dopaminergic neurons - ventral pars reticularis
- –iron containing glial cells
- –serotonin and GABA
tracts in cerebral hemisphere
- association
- -confined to a given hemi
- -connect regions of the same hemi - commissural
- -interconnect the 2 hemi - projection tracts
- -form internal capsule
- -make up ascend/descending tracts
- -connect hemi to other parts of brain and spinal cord
list association tracts
- arcuate tracts
- cingulum
- sup longitudinal fasciculus
- sup occipitofrontal fas
- inf occipitofrontal fas
- uncinate fasciculus
arcuate tracts
interconnect adjacent gyri
cingulum
connects frontal, parietal, temporal cortical areas on the medial side of each hemis
superior longitudinal fasciculus
interconnects areas w/in the frontal, parietal, occipital, temporal lobes
superior occipitofrontal fasciculus
located in medial part of hemi under lat extension of corpus callosum
interconnects the frontal lobe w/ post parts of hemi
inferior occipitofrontal fasciculus
runs btwn occipital and frontal lobes
in lat part of each hemi under insula
uncinate fasciculus
makes sharp bend about lat fissure
interconnects orbital surface of frontal lobe w/ rostral part of temporal lobe
list commissural tracts
corpus callosum
ant/post commissure
hippocampal comm
corpus callosum
interconnects neocortical areas in all lobes
unifies awareness and attention
permits sharing of learning and memory
anterior and posterior commissures
ant – interconnects areas w/in the 2 temporal lobes
post – connects cerebral hemi’s w/ sup colliculi
hippocampal commissure
interconnects 2 hippocampal formations
list projection tracts
- corticopetal
2. corticofugal
corticopetal tract and corticofugal tract
from thalamus to cerebral cortex
cerebral cortex to basal muclei and thalamus
thalamic radiation
corticothalamic fibers project cerebral cortex to thalamus
thalamocortical fibers project from thalamus to cerebral cortex
corticopontine projections
fibers project to pontine nuclei in pons
pontine nuclei projects to cerebellum
corticobulbar projections
motor cortex to cranial nerve nuclei in brainstem
corticospinal projections
motor cortex to cell groups throughout spinal cord
corticoreticular projections
motor and somatosensory cortex to brainstem reticular formations
fornix
major projection system btwn hippocampus in temporal lobe and diencephalon
optic radiation
= geniculocalcarine tract
lat geniculate body toward calcarine fissure in occipital lobe
components of limbic system
amygdala hippocampus cingulate gyrus parahippocampus gyrus hypothalamus mamillary bodies ant nucleus of thalamus
limbic system – functions
emotional and motivational aspects of behavior
provides emotional component to learning especially amygdala
associated w/ memory – hippocampus
pain, pleasure, rage
amygdala
large nuclear group in temporal lobe
receives info from olfactory tract, limbic cortex, neocortex
amygdala regions
- large basolateral region
direct input to basal ganglia and motor sys - small corticomedial group of nuclei
related to olfactory cortex - medial and central nuclei
connected to hypothalamus
functions of amygdala
relate environmental stimuli to coordinated behavioral autonomic and endocrine responses
feeding and drinking
fighting behavior
mating and maternal care
response to physical and emotional stress
damage to hippocampus
memory loss
cells undergo Ca-induced changes associated w/ memory
kluver-bucy syndrome
results from bilateral destruction of amygdala
increased sexual activity compulsive tendency to place things in mouth decreased emotions changes in eating visual agnosia
future of the prosen-, mesen-, rhomben-cephalon
prosen
future forebrain
mesen
future midbrain
rhomben
future hindbrain
major derivative of the myelencephalon
medulla oblongata
gray matter in the myelencephalon vs spinal cord
organized into nuclei interspersed among white fiber tracts
is continuous
located centrally
surrounded by myelinated/white fiber tracts
brainstem composition
mix of long fiber pathways
well organized nuclei
network of cells forming reticular formation
components:
medulla, pons, midbrain
descending tracts in medulla
corticospinal spinal tract V med longitudinal fasiculus tectospinal rubrospinal
ascending tracts in medulla
med lemniscus spinothalamic tract Spinoreticular tract spinocerebellar tract cuneocerebellar tract
inferior olivary nuclei
receive input from most motor areas of brain and spinal cord
functions:
balance, coordination, sound impulse modulation
axons project to the contralateral cerebellar hemisphere via ?
the olivocerebellar tract
these axons signal the cerebellum when a mvt deviates from the planned mvt
medulla - vital reflex centers
cardiac center
medullary rhythmicity center
vasomotor center
centers for coordination of head mvt and swallowing
medulla – roof
sup medullary velum
inf medullary velum
post choroid plexus
Wallenberg’s syndrome affects ?
spinothalamic tract spinal-trigeminal tract and nucleus CN IX and X reticular formation vestibular nuclei
Wallenberg’s syndrome results in ?
loss of pain and temp on contralateral side
difficulty swallowing
weak voice
loss of gag reflex
fiber tracts of the pons
transverse
—connects pons to cerebellum
longitudinal
- –sensory and motor
- –connects spinal cord to upper brainstem
- –goes thru pons w/o synapsing
what are the 2 longitudinal tracts that synapse in the pons?
- corticopontine tracts
synapse on pontine nuclei - corticobulbar tracts
synapse w/ neurons in motor nucleus and facial nucleus
pons – characteristics
CN 5,6,7,8
pontine nucleus
—relay info from cerebrum to cerebellum
sleep and respiratory centers
lesion to lateral half of pons
affects: trigeminal n, med lemniscus, pontocerebellar fibers
trigeminal n
loss of sensation to face
paralysis of mastication muscles
medial lemniscus
loss of joint sense on opposite side
pontocerebellar fibers
hypotonia, intention tremors, tendency to fall
bilateral lesions to ventral pons
caused by occlusion to basilar artery
interrupts corticospinal and corticobulbar tracts
results in quadriplegic, unable to speak but conscious
damage to midpons
extensive bilateral lesions involving pons and midbrain reticular formation
coma — state of sustained unconsciousness
midbrain nuclei
CN nuclei 3 and 4
red nucleus/nucleus ruber
—involved in unconscious regulation/coordination of motor function
midbrain – tectum
superior and inferior colliculi
superior colliculi
visual reflexes
projects to CN nuclei and superior cervical portion of spinal cord
also involved in visual tracking of moving objects
inferior colliculi
auditory and olfactory reflexes
midbrain — tegmentum
tracts red nucleus cerebral peduncles interpeduncular fossa substantia nigra oculomotor complex CN 4 nucleus
substantia nigra
interconnected w/ basal ganglia
involved in coordinating mvt and muscle tone
oculomotor complex
nucleus of CN 3
Edinger-westphal nucleus
—parasym control of pupillary sphincter and ciliary muscle
midbrain — periaqueductal gray
gray matter surrounding cerebral aquaduct
functions:
- -pain suppression
- -rxns to pain, threats, emotions
- -activity results in flight or fight
midbrain – decerbrate rigidity
transection of the midbrain at the midcollicular level
—causes decerebration/disconnection of cerebral control
vestibular sys drives rigidity
patient is comatose UE extension forearm pronation flexed wrists LE extension plantar flexion
metencephalon – cerebellum
controlled by motor cortex in hemispheres
connected to brainstem by 3 pairs of large fiber tracts called peduncles
- superior to midbrain
- middle to cerebellum
- inferior to medulla
functions of reticular formation
important for wakefulness
damage may result in permanent coma
receives input from cerebral cortex
modulate sensation of pain
postural reflexes
control breathing and HR
brain arousal
