Unit 7 - Diencephalon (prosencephalon)

What is the secondary embryonic vesicle from prosencephalon?

diencephalon

major parts or subdivisions of the diencephalon

third ventricle

epithalamus

hypothalamus

subthalamus

thalamus

functions of diencephalon

1. relay center for sensory input to cerebrum

2. integrative as well as relay

3. significant center for control of autonomic and endocrine functions

location of epithalamus

just superior to the midbrain tectum

what structures does the epithalamus include?

pineal gland and posterior commissure

"epiphysis cerebri"

Pineal gland (body)

what is the pineal gland filled with?

highly modified neurons called pineal or epiphyseal cells

-fenestrated vascular capillary beds are numerous as are glial support cells

do pineal tumors occur?

yes

what does the pineal gland secrete?

melatonin, serotonin, and norepinephrine

*Is the pineal gland sensitive to light directly?

no, but it is through a pathway originating in the retina and synapsing in the hypothalamus

posterior commissure

a commissure just superior to the midbrain tectum

what is located in the posterior commissure?

Pupillary light reflex fibers and nuclei

what does the subcommissural organ produce?

it MAY produce aldosterone

what cells make up the subcommissural organ?

specialized ependymal cells

what do commissural fibers do?

cross midline and connect equivalent structures on opposite sides

How does the pupillary light reflex work?

when light shines in L eye, L eye constricts but so does the R eye (somewhat) because of the posterior commissure connecting them

largest nuclei in the CNS

thalamus

included with the thalamus are the lateral and medial vehicular bodies often classified separately as the.....

metathalamus

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 inter thalamic adhesion

the thalamus forms the bulk of the side walls of which ventricle?

third

lateral to each thalamic mass is....

the posterior limb of the internal capsule

general function of the thalamus

1. all sensory input to the cerebral hemispheres, except olfaction, is relayed and integrated in the thalamus

2. helps focus the attention of the cerebral cortex; temporarily making certain cortical sensory areas especially receptive

3. pain and temp senstions

internal medullary lamina

myelinated fibers that runs through the substance of each thalamic mass and divides it into subdivisions

the thalamus is divided into equal R and L thalamic masses held together by what?

massa intermedia

largest part of the thalamus that is found only among the highest of primates

pulvinar

location of hypothalamus

below the thalamus

what does the hypothalamus form?

flor of the third ventricle and portions of the third ventricles lateral walls

what structures are included as the hypothalamus' structure?

infundibular stalk and optic chasm (not pituitary gland)

medial zone of the hypothalamus can be divided into...

anterior, intermediate and posterior areas

Does the hypothalamus work unaided or uninfluenced from other centers?

no

hypothalamus functions

-vague control over basic drives of hunger, thirst, and sex

-physcial aspects of emotional expression

-visceral functions

-endoncrine control

parasympathetic control of hypothalamus

-anterior and intermediate areas

-increases digestive motility

-decreases heart rate

-constriction of pupil

sympathetic control of hypothalamus

-posterior area

-increases heart rate and vasoconstriction

-decreases digestive motility

-responsible for pupil dilation, piloerection, and sweat gland secretions

endocrine control of hypothalamus DIRECTLY

via neuron axon extensions into posterior pituitary

endocrine control of hypothalamus INDIRECTLY

via neurohormones to control the release of anterior pituitary hormones

nuclei found in the anterior area of hypothalamus (just above optic chiasm)

supraoptic and paraventricular nuclei, suprachismatic nuclei (SCN), anterior nucleus, and preoptic area

supraoptic and paraventricular nuclei send axons down through the infundibular stalk via which tract?

hypothalamohypophyseal or supra-opticohypophyseal

where do supraoptic and paraventricular nuclei terminate?

posterior pituitary

when the supraoptic and paraventricular nuclei terminate, what do they release?

oxytocin and antidiuretic hormones

Oxytocin function

uterine contractions

ADH function

save H2O (don't pee)

suprachiasmtic nuclei function

responsible fo much of our circardial 24-25 hour rhythms such as temperature, sleep, light, feeding ,etc.

suprachiasmatic nuclei is connected to what?

pineal gland and its secretions into the blood stream

anterior nucleus

parasympathetic functions (mostly)

preoptic area (nucleus)

thermo-regulator ; especially as body heats up

nuclei found in the intermediate area of hypothalamus

dorsomedial nuclei, ventromedial nuclei, arcuate nuclei, and tuner cinerum

dorsomedial nuclei

A significant GI tract parasympathetic influence. The nucleus is fairly diffuse

ventromedial nuclei

center for eating and thirst gratification

"satiety center" or fullness center

arcuate nuclei

* Series of small nuclei in the intermediate area of the hypothalamus near the infundibular stalk that form an arch-like shape

arcuate nuclei function

contribute axons to the tuberoinfundibulnar tract

arcuate nuclei descend to the pituitary, where the group of axons terminate and do what?

-secrete their neurohormones into the perivascular spaces of the infundibular stalk

-neurohormones then pass to anterior pituitary by way of bloodstream where they influence the release of pituitary hormones "releasing factors" or "hypothalamic hypophysiotropic hormones"

tuber cinereum

The undulating bulge (barely visible externally) between the infundibular stalk and the large mammillary bodies

nuclei located in the posterior area of the hypothalamus

mammilary bodies and posterior area

mammillary bodies

nucleus important for short term memory

Koraskovs' syndrome

a disease that afflicts long-term alcoholics, leaving some abilities intact but including hallucinations and a tendency to repeat the same story

retrograde amnesia

memory loss before the incident

anterograde amnesia

memory loss comes after the trauma

posterior nuclei

thermoregulator; especially as the body cools down

-stimulates shivering

posterior area is known for what kind of actions?

diverse sympathetic actions

subthalamus location

beneath the thalamus

nuclei found in the sub thalamus

-parvocellular region of red nucleus

-superior portion of the substantial nigra

-subthalamic nuclei

function of subthalamic nuclei

sends and receives fibers to and from the globes pallid us of telencephalon

what system is the subthalamic nuclei part of?

extrapyramidal system

lesions to subthalamic nuclei

due to ballistic or hemiballism - forceful flinging movements of shoulders and/or hips