Exam One - Diencephalon and Telencephalon Flashcards
What are the 4 divisions of the diencephalon?
1 - thalamus
2 - hypothalamus
3 - epithalamus (pineal gland/habenula)
4 - subthalamus
subthalamic nucleus
involved in movement regulation with the basal ganglia.
neurons are excitatory glutaminergic neurons projecting to the internal globus pallidus
habenula
connects the limbic system and basal ganglia through the stria medullaris. also sends fibers to dopamine releasing midbrain structure. involved in drug addiction.
infundibulum
pituitary stalk connects the hypothalamus and the posterior pituitary
mammillary body
part of the hypothalamus, connect to hippocampus, involved in new memory formation
anterior perforated substance
grey matter with small holes created by lenticulostriate arteries, perforating arteries of the ACA and MCA which travel through this area and supply the internal capsule (IC) and the basal ganglia (nuclei)
posterior perforated substance
located in the interpeduncular fossa, perforated by many small holes created by small branches of the PCA, going to the thalamus
What supplies blood to the diencephalon?
circle of willis
Where is the thalamus located?
wall of the 3rd ventricle
What are thalamic nuclei connected by?
massa intermedia (interthalamic adhesion)
Why is the thalamus the “gate” to the cortex?
functions in sensory, motor, and limbic systems by gating of integrated motor and sensory input to and from the cortex.
projects specific sensory and motor cortices and association cortices
75% of thalamic neurons are ___________
projection neurons
projection neurons are involved in………. and use…….. neurotransmitter
reciprocal cortex-thalamus connection, glutamate
25% of thalamic neurons are ____________ interneurons
inhibitory
What structure divides the thalamus into three parts?
internal medullary lamina
What are the 3 subdivisions of the thalamus?
anterior, medial, lateral group
What are the subdivisions of the lateral portion of the thalamus?
dorsal tier, ventral tier, and pulvinar
anterior nucleus of the thalamus is the….
limbic relay system
input: from hippocampus
output: to cingulate gyrus
role in: memory and mood
medial nucleus of the thalamus
association nucleus, connect to prefrontal cortex
left dorsomedial nucleus: verbal learning
right dorsomedial nucleus: non-verbal learning
dorsal tier in lateral nucleus of thalamus
involved in higher functions of the brain
include:
lateral dorsal nucleus
lateral posterior nucleus
and pulvinar
ventral tier in lateral nucleus of thalamus
involved in sensory and motor integration
motor nuclei:
ventral anterior (VA) - input from basal ganglia
ventral lateral (VL) - major motor nucleus
sensory nuclei:
VENTRAL POSTERIOR LATERAL (VPL) - GENERAL SOMATOSENSORY/RECEIVE INPUT FROM OTHER SIDE OF BODY
VENTRAL POSTERIOR MEDIAL (VPM) - INPUT FROM FACE
medial geniculate nuclei - auditory system
lateral geniculate nuclei - visual system
centromedian - parafascicular nuclei
involved in generalized pain, that alerts the cortex and evokes the emotional components of pain
reticular nucleus of the thalamus
- continuation of brain stem reticular formation
- forms a capsule around the thalamus ventrally and laterally
- “pacemaker”/synchronizes thalamic activity
- ALLOWS SENSORY INPUT TO REACH CONSCIOUSNESS
- no projections to cerebral cortex
- receives input from the cortex and the reticular formation of the brainstem
- GABAergic nucleus
Most thalamic nuclei are _________ nuclei, 3 are association nuclei
relay
What is the cause of thalamic syndrome?
occlusion of the posterior cerebral artery branches (specifically thalamogeniculate artery)
symptoms of thalamic syndrome manifest contralaterally or ipsilaterally to the lesion?
contralaterally
What are the clinical presentations of thalamic syndrome?
*- thalamic pain - exaggeration of the pain due to disruptions in the thalamus, debilitating
- hemianesthesia - loss of sensation in either lateral half of the body
- hemiparesis - unilateral paresis
- sensory ataxia - lack of coordination due to dysfunction in sensory input to motor areas
components of the telecephalon
two hemispheres: each have
- outer cerebral cortex
- subcortical white matter (corona radiata and internal capsule)
- basal ganglia (controls movement)
- corpus callosum (connects 2 hemispheres)
- lateral ventricles
- 1st cranial nerve
sulci
indentations into the outer cortex/delimitate gyri
what is the deepest sulcus?
lateral fissure/sulcus
calcarine sulcus
deep, unique to primate, the primary visual cortex is found along its banks
cingulate gyrus
role in emotion processing and behavior regulation, connected to both the “emotional” lymbic system and the “cognitive” prefronal cortex
parahippocampal gyrus
involved in spatial memory and navigation
uncus
part of the parahippocampal gyrus, hook shaped most inner part of the temporal gyrus
fornix
large c-shaped, under the cc, connects the hippocampus to the mamillary bodies of the hypothalamus
brodmann’s areas
functional numbers for gyri
3,2,1
post central gyrus
primary somatosensory
4
precentral gyrus
primary motor
6
premotor, supplementary motor
17
primary visual
41
primary auditory
44 and 45
motor speech
corpus callosum connects…
camparable areas of the hemispheres
carpus callosum is..
largest cerebral commissure
allows info to be transmitted from one cerebral hemi to the other
enables bilateral memory storage
3 core components of the diencephalon and telencephalon
- thalamus (dorsal)
- basal ganglia (nuclei)
- internal capsule: collection of fibers ascending to or descending from cerebral cortex
components of the basal ganglia
- caudate nucleus
- lentiform nucleus
- associated structure: substantia nigra and subthalamic nucleus
caudate nucleus
- component of basal ganglia
- “c” shaped nucleus
- follows path of lateral ventricle
- located in lateral wall of lateral ventricle
lentiform nucleus
- putamen
-globus pallidus (internal and external)
striatum
caudate nucleus + putamen
carpus stratum
caudate + putamen + globus pallidus
Internal capsule (IC)
a massive collection of axons that are either going to (ascending) or coming from (descending) the cerebral cortex that pass between portions of the basal ganglia and thalamus
subdivision of internal capsule
- ant. limb
- post. limb
- genu:
- sublenticular
- retrolenticular
anterior limb of IC
- located: between the head of the caudate and the lentiform nucleus
- contains:
frontopontine fibers
efferents to cingulate gyrus
efferents to the prefrontal gyrus
genu of the IC
contains:
frontopontine
VA/VL cortocothalamic fibers
some corticobulbar fibers
posterior limb of IC
- located: between the thalamus and lentiform nucleus
- ascending fibers:
thalamocortical radiations - descending fibers:
corticospinal
corticopontine
corticothalamic
corticoreticular
corticorubral
corticoolivary
corticobulbar
rentrolenticular part of IC
-location: posterior to lentiform n
- fibers:
motor - parietal lobe corticopontine fibers
sensory - optic radiation fibers (damage causes visual field defects)
sublenticular part of IC
- location: under lentiform n
- fibers:
auditory radiations
What is the blood supply to IC
perforating branches of ACA and MCA
what is the blood supply to the telencephalon and diencephalon
internal carotid artery system
what is the blood supply to the brainstem, cerebellum, parts of the occip/temp lobes, and diencephalon?
vertebral-basilar artery system VBA
ICA and VBA join at the
circle of willis
the perforating branches of the circle of willis supply
deep cerebral structures
blood supply to the anterior limb of IC
mainly lenticulostriate branches of MCA
less branches of ACA
blood supply to the genu of IC
lenticulostriate branches of MCA
blood supply to the posterior limb of IC
lenticulostriate branches of MCA and ant. choroidal artery (branch of ICA)
segments of middle cerebral artery MCA
lenticulostriate artery (LSA) and M1
M1 supplies
medial temporal lobe and LSA
Where do aneurysms of the MCA frequently occur?
bifurcation of M1 trunks
association fibers establish connections between the _________ hemisphere
same
short association fibers….
connect adjacent gyri
long association fibers….
connect lobes
arcuate fasciculus
connects broca’s and qernicke’s areas, which are involved in producing and understanding language
Inferior longitudinal fasciculus (ILF)
bidirectional tract involved in processing and modulating visual cues and thus in visually guided decisions and bahaviors
uncinate fasciculus (UF)
connects parts of the limbic system with the orbitofrontal cortex, its function is unknown, one of the last white matter tracts to mature in the human brain
corpus callosum
largest side-to-sode interconnections between the two hemispheres, connects analogous areas in the two hemispheres
anterior commissure
anterior to corpus callosum
- connects the olfactory bulbs, amygdala and the medial and inferior temporal lobes
posterior commissure
posterior to corpus callosum
- fibers connect areas in the occipital lobes, primarily areas controlling pupillary response and eye movement
