Neuro - Diencephalon Flashcards
What structures make up the Diencephalon?
All structures with the term THALAMUS in their name
- Thalamus
- Hypothalamus
- Epithalamus
- Subthalamus
Of the structues that make up the Diencephalon, which is the largest subdivision of the diencephalon?
Thalamus
What is the orientation of the Hypothalamus in relation to the Thalamus?
Inferior/anterior to the thalamus
What is the orientation of the Epithalamus in relation to the Thalamus?
Superior/posterior to the thalamus
What structures make up the Epithalamus?
- Pineal body
- Habenular nuclei
- Posterior commissure
What is the orientation of the Subthalamus in relation to the Thalamus?
Directly inferior to the thalamus (related to basal ganglia)
How would you describe the location of the thalamus?
- Located bilaterally above the midbrain
- On either side of the 3 ventricle land marks
What is the posterior end of the thalamus called?
Pulvinar - overhangs the medial & lateral geniculate bodies
What is the rostral end of the thalamus called?
Anterior thalamic tubercle
White matter of the diencephalon
Radiates from the Thalamus to Cerbral Cortex
What is the External Medullary Lamina?
- Layer of myelinated fibers
- On the lateral surface of thalamus (close to internal capsule)
What does the External Medulllary Lamina separate from the rest of the thalamic mass of gray matter?
Reticular nucleus
What is the Internal Medullary Lamina of the Thalamus?
- “Y-shaped” vertical sheet of white matter
- Diveds Gray matter of the thalamus in 3 groups
What are the 3 groups that the Internal Medullary Lamina of the thalamus dived the gray matter into?
- Anterior (between the 2 lines of the “Y”)
- Medial (on the side of the stem of the “Y”)
- Lateral (on the side of the stem of the “Y”)
What does the Internal Medullary Lamina of the thalamus contain?
- Fibers connecting thalamic nuclei with one another
- Neuronal collection called intralaminar nuclei
What are the Thalamic Nuclei?
*** Fair warning, the answer to this card is A LOT but it’s just to give you and over all look of the nuclei of the thalamus, I’ll go in to each one and what they do
- Anterior Nuclei
- Medial Part: Dorsomedial nucleus
- Lateral Part: Subdivided into Dorsal Teir / Ventral Teir
Dorsal Teir:
- Lateral Dorsal Nucleus (LD)
- Lateral Posterior Nucleus (LP)
- Pulvinar (P)
Ventral Teir:
- Ventral Anterior nucleus(VA)
- Ventral Lateral Nucleus (VL)
- Ventral Posterior Nuclus ****
Ventral Posterior Nucleus further subdivides in to:
Vental Posteromedial Nucleus (VPM)
Vental Posterolateral Nucleus (VPL)
What is the Anterior Nuclei of the thalamus responsible for?
- connect with limbic structures
- exert influcences on emotional states / memory
What is Dorsomedial nucleus (medial part) responsible for?
Integrating information and relating the info to the individual’s emotional state for:
- sensory
- motor
- visceral
- olfactory
What is the function of the Pulvinar of dorsal teir of the lateral part of the thalamus?
- visual processing in higher cortical areas
** pt’s with a pulvinar lesion show deficits in filtering out distracter info, thus making it hard to maintain attention
What is the Vental Anterior Nucleus (VA) responsible for>
(ventral tier of the lateral part of thalamus)
- influences the activities of the motor cortex
- invloved in plannning/initiating movements
What is the Ventral Lateral Nucleus (VL) responsible for?
(in the ventral teir of the lateral part of thalamus)
- Active during both passive/active movement of contralateral parts of the body
- relays motor feedback from the cerbellum to the cerebral cortex
Ventral Posteromedial Nucleus (VPM) uses what pathway?
(of ventral posterior nucleus in the ventral tier of the lateral part of the thalamus)
Trigeminothalamic Pathway
Ventral Posterolateral Nucleus (VPL) uses what pathway?
(of ventral posterior nucleus in the ventral tier of the lateral part of the thalamus)
Medial lemniscus
Other Nuclei of the thalamus?
- Intralaminar nuclei
- Midline nuclei
- Reticular nucleus
- Medial geniculate body
- Latera geniculate body
Where is the Intralaminar nuclei located?
Within the Internal Medullary Lamina
Where is the Midline cuclei located?
adjacent to 3rd ventricle and in interthalamic adhesion
Where is the Reticular Nucleus located?
Between External Medullary Lamina and Posterior Limb of Internal Capsule
Where is the Medial geniculate body located and what is it’s pathway?
- located on posterior surface of thalamus beneath the pulvinar
- auditory pathway
Where is the Lateral geniculate body located and what is it’s pathway?
- located on the undersurface of thalamus beneath the pulvinar
- visual pathway
What is the nickname for the Thalamus?
“secretarty” to the cerebral cortex
All sensory information except for what, must be processed/inegrated in the thalamus?
Oflactory (smell)
The thalamus integrates what type of motor movements?
Voluntary motor movements
(via ventral anterior/vental lateral nuclei - VA/VL nuclei)
What affects does the thalamus’ connection with the prefrontal cortex via the dorsomedial nucleus have?
affects subjective feelings and personality of individuals
What affects does the thalamus’ connection to the limbic system (AN) have?
affects emotional status of individuals
What could cause ds. to the thalamus?
- tumors
- decreased blood supply by posterior cerbral artery (PCA)
What will you see in Thalamic Pain Syndrom?
- spontaneious/excruciating pn on opposite side of lesion
- Pn is aroused by light touch / cold / hot
- Pn does’t respond to powerful analgesic drugs
- abnormal involuntary mvmts : Choreo-athetosis w/ ataxia
What will you see in Thalamic Hand ?
Contralater hand will be:
- pronated
- flexed
- metacaropophalangeal jt - flexed
- interphalangeal jts - extended
What is the location of the Hypothalamus?
Inferior/anterior to the thalamus
What ventricle does the hypothalamus form the floor to?
It’s the floor of the 3rd ventricle
What is the extent of the hypothalamus (rostral to caudal)?
From optic chiasm to mamillary bodies
What is the blood supply to the hypothalamus?
Anterior cerebral artery (ACA)
What are the external landmarks of the hypothalamus?
- optic chiasm
- infundibulum
- tuber cinereum & the median eminence
What splits the hypothalamus into medial/lateral parts?
The fornix
Does the medial or lateral part of the hypothalamus contain most of the hypothalamic nuclei?
The medial portion
What is the Fornix?
White matter leaving the hippocampus
Where does the hippocampus project to?
Mainly to the mamillary bodies
Where do the Mammilary bodies project to?
Thalamus via the mammillothalamic tracts
Which 3 systems does the Hypothalamus subserve?
- Autonomic nervous system
- Endocrine system
- Limbic System
What is the “overall” function of the hypothalamus?
- Homeostasis
- survival
What are the nuclei of the hypothalamus?
*** Fair warning, there are a lot. I will go in to detail over each. This is just an overall view
- Medial Preoptic Nucleus
- Suprachiasmatic Nucleus
- Anterior Nucleus
- Paraventricular Nucleus
- Supraoptic Nucleus
- Dorsomedal Nucleus
- Arcuate Nucleus
- Mammilary Nucleus
- Posterior Hypothalamic Nucleus
- Lateral Hyopthalamic Nucleus
What is the Medical Preoptic Nucleus responsible for?
Regulates release of gonadotrophic hormones frm the adenohypophysis
Sexual Arousal
What is the Suprachiasmatic Nucleus responsible for?
- Receives direct input from the retina
- Plays a role in Circadian Rhythms (daily rhythms)
What is the Anterior Nucleus of the hypothalamus responsible for?
- Plays a role in Temp Regulation
- Stimulates parasympathetic nervous syst. leading to Vasodilation
Destruction of the Anterior Nucleus of the Hypothalamus will result in what?
Hyperthermia
What is the Paraventricular Nucleus responsible for?
- Synthesizes Antidiuretic & Oxytoin Hormone
- Gives rise to hypothalmohypopyseal tract
- Regulates Water Balance (conservation)
Destruction to the Paraventricular Nucleus will result in what?
Diabetes Insipidus
What is the Supraoptic Nucleus responsible for?
Synthesize Antidiuretic & Oxytocin Hormome
(similar to?…. Paraventricular Nucleus)
What is the Dorsomedial Nucleus responsible for?
Agressive behavior and rage results when this nucleus is stimulated in animals
(connected with Limbic syst.)
What is the Arcuate Nucleus responsible for?
Produce hypothalamic relasing/inhibiting hormones that control anterior pituitary through the hypophyseal portal circulation
What is the Mamillary Nucleus responsible for?
- Receives input from Hippcampal formation (through fornix)
- Projects to Anterior Nuclei of Thalamus via mamillothalamic tract (part of Papez Circut)
- Processes info related to Emotional Expression
What is the Posterior Hypothalamic Nucleus responsible for?
- Plays a role in Thermal Regulation (conservation/increased prodcution)
- Regulates sympathetic nervous syst.
- Stimulation causes Vasoconstriction of the sking blood vessels
What is a fundamental component of the Limbic Syst.?
Papez Circut
What is Papez Circut ?
Closed neural circuitry that statrs/ends in the hippcampus
AKA: Medial Limbic Circut
What is the Lateral Hypothalamic Nucleus responsible for?
Induces eating
Lesions to the Lateral Hypothalamic Nucleus cause what?
- Anorexia
- Starvation
What is the Zona Incerta and what does it control?
- Cells alongside the Lateral Hypothalamic Nucleus
- Controls water intake (drinking)
What is the largest projection of the Hypothalamus?
Fornix
(projects from hippocampal formation to mamillary nuclei)
Where does the Mamillothalmic Tract project?
From Mamillary nuclei to anterior nucleus of thalamus
(part of Papez Circut)
What is the major pathway from the Amygdala to the Hypothalamus/septal nuclei?
Stria Terminalis
Which tract conducts fibers from the Supraoptic and Paraventricular nuclei to the neurohypphysis?
Hypothalamohypophyseal Tract
(Realse site for ADH/Oxytocin)
Which tract contains direct descending autonomic fibers that influence preganglionic sympathetic neurons of the intermediolateral cell column?
Hyopthalamospoinal tract
The Hypothalamospinal Tract as descending autonomic fibers to?
- Intermediolateral cell column - Lateral horna of T1-L2
- Preganglionic neurons to the sacral parasympathetic nucleus (S2-S4)
Interruption above the first thoracic segment (T1) in the Hypothalamospinal Tract will result in what?
Horner’s Syndrom
The Hypothalamospinal tract provides a link to?
- Thoracolumbar (sympathetic) lateral horn cells
- sacral (parasympathetic) lateral horn cells
fibers lie adjacent to the lateral horns
What will present with Horner’s Syndrom?
- Loss of sweat on the face
- partially drooping eye
- small pupil
The Anterior Hypothalamus has an exitatory effect on?
Parasympathetic Nervous syst.
The Anterior Hypothalamus regulates/maintains body temp, destruction to this area will result in?
Hyperthermia
The Posterior Hypothalamus has an exciatroy effect on?
Sympathetic Nervous Syst.
The Posterior Hyopthalamus helps produce/conserve heat, destruction to this will result in?
Inability to thermoregulate
Which two Hypothalamic nuclei play a role in food intake regulation?
- Ventromedial nucleus
- Lateral Hypothalamic nucleus
Which Hyopthalamic Nucleus INHIBITS the urge to eat?
Ventromedial nucleus
Destruction results in:
- hyperphagia
- obesity
- savage behavior
Which Hypothalamic Nucleus INDUCES the urge to eat?
Lateral Hypothalamic Nucleus
Destrcution results in:
- anorexia
- starvation
- emaciation
