prosencephalon (forebrain)- diencephalon Flashcards
what is the general function for the diencephalon?
- most significant relay center for sensory input to the cerebrum (all sensation except olfaction)
- autonomic and endocrine fx
where is the epithalamus located?
superior to the midbrain tectum
what structures are in the epithalamus?
pineal gland and posterior commissure
what is another name for the pineal gland?
epiphysis cerebri
what is the pineal gland filled with?
highly modified neurons called pineal or epiphyseal cells, fenestrated vascular capillary beds and glial support cells
what does the pineal gland excrete?
fenestrated capillaries- secrete melatonin, serotonin and norepinephrine
the pineal gland is not sensitive to light directly but through a pathway originating in the?
retina and synapsing in the hypothalamus (suprachiasmatic nucleus)
how many people are affected by SAD?
1 in 20
what is a small but identifiable commissure just superior to the midbrain tectum?
posterior commissure
what are located in the posterior commissure?
pupillary light reflex fibers and nuclei
what is a small structure just anterior and inferior to the posterior commissure?
subcommissural organ- may produce aldosterone
what is the largest of all nuclei of the CNS?
thalamus
what is the metathalamus?
lateral and medial geniculate bodies included with the thalamus but classified separately
where is the thalamus located?
thalamus means couch- looks like it is sitting; forms the bulk of the side walls of the 3rd ventricle
what is the thalamus composed of?
2 large ovoid masses of gray matter joined together by a bridge of gray substance called the MASSA INTERMEDIA or INTERTHALAMIC ADHESION
lateral to each thalamic mass is the?
posterior limb of the internal capsule
what are 3 general functions of the thalamus?
- all sensory but olfaction is integrated here
- focus the attention of the cerebral cortex
- some pain and temp sensations; higher relay is needed for complete integration
what is the structure of myelinated fibers that runs through the substance of each thalamic mass and helps divide them into subdivisions?
internal medullary lamina
the thalamus is divided into equal right and left thalamic masses held together by?
the massa intermedia
what is the largest part of the thalamus and only found in highest of primates?
pulvinar
where is the hypothalamus located?
forms the floor of the 3rd ventricle ventricle and portions of the lateral walls
the hypothalamus includes as part of its structure the _____ and _____
infundibular stalk and optic chiasm NOT pituitary
what are the zones and areas of the hypothalamus?
medial and lateral zones and anterior, intermediate and posterior areas
what are the basic functions of the hypothalamus?
- hunger, thirst and sex
- physical aspects of emotional expression
- central control over visceral functions
what is the parasympathetic control of the hypothalamus?
increase digestive motility
decrease heart rate
constrict pupils
what is the sympathetic control of the hypothalamus?
increase heart rate and vasoconstriction
decrease digestive motility
pupil dilation, piloerection and sweat secretions
what is the endocrine control of the hypothalamus?
directly- neuron axon extensions into POSTERIOR pituitary
indirectly- neurohormones to control release of ANTERIOR pituitary HORMONES
the anterior area of the hypothalamus just above the optic chiasma include which nuclei? (5)
supraoptic and paraventricular
suprachiasmatic
anterior
pre optic area nucleus
supraoptic and paraventricular nuclei send axons down through the infundibular stalk via what?
hypothalamohypophyseal or supra-opticohypophyseal tract and terminate in the posterior pituitary
what do the supraoptic and paraventricular nuclei release?
oxytocin and ADH
what is the suprachiasmatic nuclei responsible for?
circadian rhythms such as temperature, sleep, light, feeding etc- connected to pineal gland and secretions to bloodstream
what is the anterior nucleus of the hypothalamus known for?
primarily parasympathetic functions
what is the pre optic area of the hypo responsible for?
a thermo-regulator; especially as body heats up
what are the nuclei of the intermediate area of the hypothalamus? (4)
dorsomedial
ventromedial
arcuate
tuber cinereum
what is the dorsomedial nucleus responsible for?
significant GI tract parasympathetic influence
what is the ventromedial nucleus responsible for?
satiety center- eating and thirst gratification
what do the arcuate nuclei contribute axons to?
tuberoinfundibular tract- terminate and secrete neurohormones into perivascular spaces of infundibular stalk; then pass to anterior pituitary where they influence release of pituitary hormones; “releasing factors”
what is a term used to describe the undulating bulge between the infundibular stalk and large mammillary bodies?
tuber cinereum- several of nuclei including arcades create this “gray swelling” or tuber cinereum
what are the nuclei included in the posterior area of the hypothalamus?
mammillary bodies
posterior nuclei
mammillary bodies are important for?
short term memory- korsakovs syndrome- alcohol
posterior nuclei of posterior hypothalamus are responsible for?
thermoregulation- body cools down, shivering
the posterior area of the hypothalamus is known for diverse ______?
sympathetic actions
which area gives rise to the anterior pituitary and intermediate pituitary?
rathke’s pouch (oropharyngeal membrane)
the posterior pituitary develops from the _____ embryologically?
diencephalon
describe the differences between the posterior and anterior pituitary travel?
posterior- mere extension of brain and neurons run directly into its substance
anterior- receives its hypothalamic influence via bloodstream
where does most blood to the pituitary and infundibular stalk come from?
branches off the internal carotid arteries
within the infundibular stalk the small arteries break into highly permeable capillaries called
fenestrated sinusoids- these pick up “releasing factors” from tuberoinfundibular tract fibers
once releasing factors enter the substance of the anterior pituitary they exert control on the release of what?
pituitary hormones
which veins are porting blood between 2 capillary beds of the anterior pituitary?
hypophyseal portal veins
where is the subthalamus located?
just under the lateral ventral aspect of the thalamus
what nuclei are present in the subthalamus?
parvocellular region of the red nucleus
superior portion of substantia nigra
subthalamic nuclei
what is the function of the subthalamic nuclei?
part of the extrapyramidal system and sends and receives fibers to and from the globus pallid us of the telencephalon
what do lesions in the sub thalamus present as?
dramatic forceful flinging movements of shoulders or hips- ballism or hemiballism
