anatomy Flashcards

1
Q

What are the landmarks that surround the hypothalamus?

A

Hypothalamic sulcus

anterior sulcus

lamina terminalis

chismatic cistern

optic chiasm

interpeduncular cistern

mammillary body

midbrain mass intermedia

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2
Q

What does the 3rd ventricle seperate?

what is the floor of the hypothalmus?

A

walls of the hypothalmus

The floor of the hypothalamus includes the tuber cinereum and median eminence

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3
Q

What are the medial/lateral amd anterior/posterior of the hypothalmus?

A

medial/lateral- optic tracts

anterior-optic chiasm

posterior- posterior perforated substance

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4
Q

hypothalmus with nuclei and tracts?

A
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5
Q

What descends the hypothalmic grey?

A

the fornix (circled in green)

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6
Q

What doe sthe fornix connect?

A

a large, myelinated limbic fiber bundle that connects hippocampus to mammillary nucleus

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7
Q

optic tracts

A
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8
Q

What is a major landmark of the hypothalamus?

A

Optic Chiasm

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9
Q

What does the fornix divide the hypothalamus into?

A

medial zone

lateral zone

periventricular zone is adjacent to the 3rd ventricle

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10
Q

What is lateral to the lateral hypothalamus?

What does it include?

A

Lateral to lateral hypothalamus is the substantia innominata (part of the general area called the basal forebrain)

Area includes nucleus basalis of Meynert, a major player in cortical function

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11
Q

What passes rostrocaudally through the lateral hypothalamic zone?

A

Medial forebrain bundle

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12
Q

What is the hypothalamic nuclei subdivided into?

What lies between the 3rd ventricle and the fornix in the medial hypothalamic zone?

A

anterior (preoptic)

middle(tuberal)

posterior (mammillary)

Between 3rd ventricle & fornix column are 10 nuclei named for position or shape

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13
Q

What nuclei lie in the anterior zone?

A

5 nuclei: 3 anteriormost named in relation to the optic system

Preoptic nucleus

suprachiasmatic nucleus

supraoptic nucleus

anterior nucleus

paraventricular nucleus

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14
Q

What nuclei lie in the middle zone?

A

3 nuclei

Ventromedial

dorsomedial

arcuate

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15
Q

Which nuclei lie in the posterior zone?

A

2 nuclei

posterior

mammillary

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16
Q

Which tract ascends out of the mammillary nucleus?

A

mammillothalmic tract

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17
Q

How does the lateral hypothalmus send and receive fibers?

What is the cousre of the medial forebrain?

A

Lateral hypothalamus sends and receives fibers via medial forebrain bundle (MFB) as do other parts of the hypothalamus.

MFB courses from forebrain rostrally through brainstem caudally.

18
Q

What is the tubermammillary nucleus of the LHA function for the brain?

A

part of the brain’s sleep-wake circuitry and is involved in wakefullness (cortical arousal).

19
Q

Where is the only source of orexineergic nuerons in the CNS?

what is the role of orexin?

where does orexin neurons output to?

A

Lateral hypothalamus is the only source of orexinergic neurons in the CNS.

Neurotransmitter orexin plays a primary role in wakefullness.

Orexin neurons output to other neurotransmitter systems involved in arousal.

20
Q

What is the affect of dysregulatin orexin?

A

Dysregulation or degeneration of LHA orexin neuron circuits is implicated in excssive sleepiness (hypersomnolence), cataplexy (loss of muscle tone), and narcolepsy (sudden wake to REM sleep-like state).

21
Q

What type of regulation is the lateral hypothalmus involved in?

What is the affect of stimulating the lateral hypothalmus?

What do lesions in the lateral hypothalmus produce?

A

Lateral hypothalamus is involved in appetite control (regulation of food intake)

stimulation causes hyperphagia

lesion produces anorexia

22
Q

What is the function of the Ventromedial hypothalmus?

What does stimulation of the ventromedial cause?

What does lesions of the ventromedial hypothalmus cause?

A

LHA in regulation of food intake

Considered a satiety center (deciding when to stop eating)

stimulation inhibits eating (anorexia)

lesion causes overeating (hyperphagia)

23
Q

How does leptin(anorexigenic) and ghrelin (orexigenic) molecules gain acces to the hypothalamic feeding regulation nueral network?

A

qprobably through the median eminence, one of the leaky-capillaried circumventricular organs (CVO)

24
Q

What is the anterior hypothalamic nucleus regulate?

What does the anterior (preoptic) area have for this regulation?

A

Anterior hypothalamic nuc. is involved in temperature regulation

anterior (preoptic) area has both cold and heat sensitive neurons (thermostat)

at high blood temperature, regulates mechanisms of heat dissipation

25
Q

What is the posterior hypothalamic nucleus involved in?

How does it regulate this?

A

Posterior hypothalamic nucleus is involved in temperature regulation

regulates mechanisms of heat production when blood temp. is low

26
Q

What is the dorsalmedial hypothalamic nucleus involved in?

What does stimulation of the dorsalmedial hypothalamic nucleus?

A

Dorsomedial hypothalamic nuc. is involved in regulating emotion (aggression)

Stimulation can elicit defensive-aggressive behaviors (“sham-rage”) in the absence of any contextual elicitors.

27
Q

How does the mammillothalmic tract reach the anterior nucleus?

A

mamillothalamic tract ascends into and through thalamus to reach anterior nuc.

28
Q

external view of the mammillothalmic tract.

large vertically oriented myelinated bundle

A
29
Q

Which tract is the main regulator ofthe autonomic system?

A

paraventricular nucleus

Projects to both parasympathetic & sympathetic preganglionic neurons via the hypothalmospinal

Hypothalamospinal tract lesion effects would include ipsilateral Horner syndrome

30
Q
A
31
Q

What is the suprachiasmatic nucleus helps regulate?

where does it receive input/output from?

A

Suprachiasmatic nuc. is involved in regulation of circadian rhythms (≈ 24hr)

Receives retinohypothalamic fibers with info about presence/absence of light

Output via sympathetic system stimulates pineal to secrete melatonin in the dark

32
Q

What lies on the floor of the 3rd ventricle and what is it continuous with?

A

infundibulum it is continuous with the pituitary

the pituitary is regulated by the hypothalamus

33
Q

What are the cells of the pituitary?

A

Adenohypophysis is secretory cell rich (dark, cell bodies stained with H&E)

Neurohypophysis is axon rich (pale, poorly stained with H&E)

34
Q

What is the median emminance?

A

The median eminence is a ridge of gray just posterior to the pituitary stalk

35
Q

What is Supraoptic and the paraventricular nucei involved in?

How are oxytocin and antidiuretic hormone transported?

Where does nerve terminals release these hormones?

A

in neuroendocrine regulation via posterior pituitary (neurohypophysis; pars nervosa)

Oxytocin and antidiuretic hormone (ADH) [argenine vasopressin (AVP)] are transported via supraopticohypophyseal tract axons to posterior pituitary

Nerve terminals release hormones near inferior hypophyseal a. capillaries

36
Q
A
37
Q

Where does the supraoptic and paraventricular nuclear axons project?

What are these projections

where does the axon terminals dump oxytocin and ADH?

A

Supraoptic and paraventricular nuclear axons project to posterior pituitary

These projecting neurons are large (magnocellular)

Axon terminals dump oxytocin & ADH into space around fenestrated capillaries

38
Q

Where does the stimulus for ADH (to retain water) originate?

A

from osmolality detecting neurons of the nearby organum vasculosum of the lamina terminalis (OVLT)

39
Q

What role doe the MFB play in oxytocin release?

A

MFB plays a major role in reproduction by transmitting feedback from cervix (prepartum) and breast (postpartum) to hypothalamus to stimulate oxytocin release

40
Q

What role does the proptic and arcuate nuclei play in neuroendocrine release?

where does their axons terminate?

A

preoptic & arcuate nuclei are involved in neuroendocrine regulation via anterior pituitary (adenohypophysis; pars distalis)

Axons terminate near superior hypophyseal a. leaky capillaries in the medial eminence of the infundibulum

41
Q

Where does the preoptic and arcuate axons dump regulatory axons?

A

preoptic & arcuate axons dump regulatory hormones (trophic [tropic] factors) into portal veins

anterior pituitary cells in turn dump hormones into systemic veins

42
Q

The 2 pathways of neuroendocrine integration (parvi- and magno- )

A