Lecture 12 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
What is the largest structure of the epithalamus?
Pineal body
-innervated by sympathetic fibers
Assists in controlling circadian rhythm and impacts glandular secretions
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
What are the functions of the thalamus?
Filters and processes info going to cortex from
-basal ganglia
-cerebellum
-all sensory system except olfactory
Relays input to discrete areas of cortex (regulates corticoneuronal activity)
All thalamic nuclei project to the cerebral cortex except for….
Thalamic reticular nucleus
Most Thalamic efferent and afferent pass through the…
Thalamic reticular nucleus
Note: 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 info from basal ganglia, cerebellum, and sensory systems to cerebral cortex
What do association nuclei do?
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
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
Describe pusher syndrome/lateropulsion due to thalamic lesions
Pushing towards weaker side/ affected side
-accompanied usually by posterior push
-patients are slower to progress
Thalamic lesions can disrupt contralateral sensation. Most commony affected is ______
Proprioception
note: thalamic pain syndrome is rare but severe
The hypothalamus is separated from the thalamus by the….
Hypothalamic sulcus
What forms the posterior aspect of the hypothalamus?
mamillary bodies
Why is the hypothalamus necessary for survival?
Pairs actions to visceral functions
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
Where is the pituitary gland contained?
Sella Turcica/pitutary fossa of sephenoid bone
What is the pathway that the hypothalamus communicates with the pituitary gland?
hypothalamus -> infundibulum -> pituitary stalk -> Pituitary gland
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
Secretions from the posterior pituitary are what?
Neuro-hormones
Neurohormones secreted by the hypothalamus cause increase/decrease in _________ secretions
anterior pituitary
Note: ant pituitary gland has glandular cells that secrete into bloodstream
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
