Dienchephalon Pt2 Flashcards
What are the 4 structures of the Diencephalon?
Subthalamus
Epithalamus
Thalamus
Hypothalamus
The subthalamus/subthalamic nuclei are functionally a part of what?
The basal ganglia
Where is the subthalamus located?
-Substantia nigra
-thamalus
-hypothalamus
Superior to substantia nigra in midbrain
inferior to thalamus
lateral to hypothalamus
Subthalamus is essential for controlling __?
fine tuning movement
Substantia nigra helps modulate movement by influencing what structures?
basal ganglia (GP,SN)
Substantia nigra has crucial role in regulation of ?
regulation of motor control and coordination of voluntary movement
-role in cognitive and emotional processing
The epithalamus encompasses several small nuclei including?
-pineal body
-habenula
-parts of pretectum
Function of epithalamus?
regulation of circadian rhythms, emotional responses, endocrine activity
What is the largest structure of the epithalamus?
Pineal body
-innervated by sympathetic fibers
Assists in controlling circadian rhythm and impacts glandular secretions
what are large collections of nuclei in 2 egg shaped structures immediately superior to top of BS and midbrain
thalamus
is thalamus white or gray matter?
gray
What is intramedullary lamina?
White matter that divides thalamus into anterior medial and lateral groves
(Thalamus is made of gray matter)
The lateral wall of the thalamus is formed by thin sheets of cells called….
Thalamic reticular nucleus
What separates the L from R thalamus. ________
the medial thalamic wall of each side formed by the thin sheets called. _______
3rd ventricle
Midline nucleus
The R and L thalamus are joined in most humans brains by what is called the…
Masa intermedia/ inter thalamic adhesion
What supplies blood to the thalamus?
deep branches of the posterior cerebral artery
-thalamoperforator artery
-thalamogenticulate artery
-posterior choroidal artery
thalamus acts as a filter and processor of info to the cerebral cortex from?
-basal ganglia
-cerebellum
-all sensory system except olfactory
How is thalamus a relay station?
relays processed input to discrete areas of cerebral cortex, thereby regulating cortical neural activity
The thalamus is involved in motor control explain
movement initiation and coordination, fine tuning of voluntary movements
thalamus regulates __, ___, ___?
arousal, consciousness, and sleep
thalamus is involved in emotions, ____, ____?
emotions, memory, and decision making
All thalamic nuclei project to the cerebral cortex except for….
Thalamic reticular nucleus
What are the two TRN?
- thalamocortical fibers
-corticothalamic fibers
Most Thalamic efferent and afferent (to/from cerebral cortex) pass through the…
Thalamic reticular nucleus with collaterals synapsing with TRN cells
many TRN neurons contain?
GABA (inhibitory)
What are the 3 main functional groups of nuclei in the thalamus?
-Relay Nuclei
-Association Nuclei
-Nonspecific nuclei
what do relay nuclei do?
Transmit motor and sensory info from basal ganglia, cerebellum, and sensory systems to cerebral cortex
What do association nuclei do?
Higher order processing
Process memory and emotion info
Intregrate different sensory pathways
Connect to specific areas of cerebral cortex with same areas projecting back to the nuclei (2 way talk)
What do the nonspecific nuclei do?
Regulate consciousness, arousal, attention
Cerebellum projects thru ___ to ____ , relaying signals to ___ in primary and premotor cortices
Superior cerebellar peduncles to thamalus
UMN
Spinocerebellar output
from?
from?
through? to?
from vermis
from intermediate zone
through SCP
to thalmus
Closed Cerebro-cerebellar-cerebral loop
from?
afferents enter thru?
efferents leave via? to?
from lateral cerebellar cortex
afferents enter thru MCP
efferents leave via SCP to thamalus
Hyper direct (stop) pathway
Projection from cortex to subthalamic nucleus in basal ganglia
Rapid inhibiton of motor responses/ stopping of action.
Inhibiton of thalamocortical motor circuits
Indirect (no-go) pathways
Projection from putamen to EXTERNAL globus pallidus and subthalamic nucleus
Suppression of inhibiton of unwanted motor responses
Increases inhibitions on thalamocortical motor circuits
The cerbellum projects through ______ peduncles to the thalamus, relaying signals to UMNs in primary and premotor cortices
Superior cerebellar peduncles
Where is spinocerebellar output from?
From Vermis and Intermidiate zone through the superior cerebellar peduncle to thalamus
Where do afferents and efferents of the cerebro-cerebellar-cerebral loop enter and leave?
From lateral cerebellar cortex
Afferents enter cortex through middle cerebellar peduncle
Efferents leave via the superior cerebellar peduncle to thalamus
Afferents _____ the cerebellum and efferents ______ the cerebellum
But this doesn’t mean they aren’t afferent/efferent (the other one) when it enters the cortex
afferents(arrive)- enter
efferents(exit)- leave
thalamus and hypothalamus is important for?
sleep regulation
alertness
how is the thalamus related to descending tracts for motor function?
thalamus recieves input from:
CE via SCP to VL and VA thalamus
SCP –> CE –> thalamus
BG –> via GPi and SPr to VL and VA of thalamus
sensory pathways via spinothalamic and DCML –> VPL and VPM
output:
VA/VL nuclei send excitatory to primary motor cortex and premotor
Describe pusher syndrome/lateropulsion due to thalamic lesions
Pushing towards weaker side/ affected side
-accompanied usually by posterior push
-patients are slower to progress
pt with right stroke pushes where?
to the left and back because left is weaker
Thalamic lesions can disrupt contralateral sensation. Most commony affected is ______
Proprioception
note: thalamic pain syndrome is rare but severe
true or false
relay sensory neurons can distrupt contralateral sensation
true most commonly proprioception affected
The hypothalamus is separated from the thalamus by the….
Hypothalamic sulcus, shallow groove on wall of 3rd ventricle
What forms the posterior aspect of the hypothalamus?
mamillary bodies
Why is the hypothalamus necessary for survival?
Pairs actions to visceral functions
hypothalamus forms walls and floor of the inferior part of
3rd ventricle
What are the functions of the hypothalamus?
(HEAL)
Homeostatic function
Endocrine Control
Autonomic Control (sympathetic NS)
Limbic system (emotions)
The hypothalamus controls circadian rhythm through…
light sensitive receptors
sleep can be facilitated or inhibited
Additional hypothalamic functions
appetite- from hormones
Thirst- from osmoreceptors
Body heat regulation
Sexual development/desire/nuturing behaviors
what controls the pituitary gland
hypothalamus
-it monitors the internal environ and responds by secreting hormones that regulate the pitutary activity
Where is the pituitary gland contained?
Sella Turcica/pitutary fossa of sphenoid bone
What is the pathway that the hypothalamus communicates with the pituitary gland?
hypothalamus -> infundibulum -> pituitary stalk -> Pituitary gland
HIPsPg
The anterior pituitary gland comes from what kind of tissue?
Meanwhile the posterior pituiary is what kind of tissue?
Anterior - Epithelial
Posterior - a continuation of brain tissue, outgrowth of interior brain in region of hypothalamus
(neural tissue)
Secretions from the posterior pituitary are what?
Neuro-hormones
Neurohormones secreted by the hypothalamus cause increase/decrease in _________ ?through?
anterior pituitary hormone through specialized vascular portal system
Note: ant pituitary gland has glandular cells that secrete into bloodstream
____pituitary gland has glandular cells that secrete into bloodstream
anterior
What hormones does the hypothalamus cause the ANT PIT to release?
GH. TSH, ACTH, LH, FSH, prolactin
What does ACTH do?
facilitates the release of corticosteroids from adrenal cortex which inhibits immune reaction/inflammation. Increases glucose production and reduces glucose use by muscles
What does LTH and FSH, prolactin do?
impacts ovaries/testes and milk production in lactating females
Where do action potentials from the hypothalamus travel to reach the posterior pituitary
pituitary stalk
What are the 2 hormones released by post pituitary
ADH- increased reabsorb of water
Oxytocin - uterine contraction
What are limbic pathways and what is the order?
emotional influences on autonomic and homeostatic pathways
Hippocampus > fornix > hypothal mammillary bodies
Mammillary bodies> mammillothalamic tract > thalamus > limbic cortex of cingulate gyrus
The ______ has reciprocal connections with hypothalamus via stria terminalis and amygdalofugal pathway
amygdala
Just know amygdala connects to hypothalamus and links emotions to sympathetic and parasympathetic nervous system
__________ (tumor) make up 10-17% of all intracranial neoplasms
Pituitary adenomas (tumor)
Pituitary adenomas (tumor) usually are _____ growing and _______
slow growing and benign
Pituitary adenomas (tumor) Can arise from any of ________________
Can arise from any of anterior pituitary cell types that secrete hormones
note: these tumors are not under normal hypothal control, causing a variety of different syndromes
Even microadenomas of 1 mm or less can cause sig endocrine issues
Larger ones put pressure on surrounding structures such as _____________
optic chiasm
Causing bitemporal hemianopia
