Anatomical Basis of Sleep and Comas Flashcards
periaqeductal gray matter
- located where?
- has what anatomic relations?
- divided into what regions? based on what?
- location: around cerebral aqueduct (3rd ventricle) for its entire length
- relations: continuous with the periventricular gray matter (cortex surrounding 3rd ventricle)
- regions: control descneding pathways for
- ventral - arousal, REM sleep
- ventrolateral - arousal, REM sleep, pain modulation
- lateral - pain modulation
- dorsomedian - pain modulation
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what periaqeductal gray matter column function in arousal?
- ventral column
- ventrolateral coluomn
which periaqeductal gray matter columns function in control of REM sleep?
- ventral column
- ventrolateral column
which periaqueductal gray matter columns modulate pain?
- dorsomedian
- lateral
- ventrolateral
basal forebrain
- location
- anatomic relations
- features
- location: portion of inferior frontal lobe that is
- relations:
- rostral to the hypothalamus
- joins the temporal & frontal lobes
- features: dominanted by the olfactory trigone, which:
- is bordered
- rostrally by the:
- medial olfactory striae
- lateral olfactory striae
- caudally by the: the diagonal band of brcoa
- rostrally by the:
- contains the: anterior perforated substance
- is bordered
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the olfactory trigone is
- located where?
- defined by what borders?
- characterized by what features?
- location: basal forebrain
- borders:
- rostrally: medial & lateral olfactory straie
- caudally: diagonal band of broca
- contains: anterior perforated substance
- groups of neurons with one especially prominent: basal nucleus of meynert
- perforated by anterior cerebral artery
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what is the anterior perforated substance?
what is another name for it?
what features does it contain?
- aka substanita innomata
- a group of poorly defined neurons with in the olfactory trigone
- features:
- perforated by anterior cerebral artery
- contains the basal nucleus of meynert
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the basal nucleus of meynert
- is located where?
- has what role?
- is clinically relevant how?
- location: in the anterior perforated substance within the olfactory trigone
- role: sends widespread cholinergic projections throughout the
- cerebral cortex -> general arousal
-
hippocampus -> neural plasticity & learning
- in conjuction w/ diagonal band of broca
- clinical: damage to this nucleus leads to dementia (ex- altzeimers)
what is the treatment for damage to the basal nucleus of meynert?
why?
- ACh
- this nucleus mediates arousal / learning & plasticity via widespared cholinergic projections
what borders the hypothalamus
- superiorly
- rostrally
- cadually
- superiorly: thalamus
- rostrally: optic chiasm
- cadually: mamillary bodies
what major nuclei make up the hypothalamus?
what is the role of each nucleus?
- tuberomamillary nulceus (histamingergic center): stimulates arousal - by directly cholinergic axons into cerebral cortex
- lateral hypothalamus: stimulates arousal - by exciting the tuberomammillary nucleus
- ventrolateral preoptic nucleus: promotes sleep - by sending inhibitory signals to brain centers that promote alertness
which hypothalamic nucleus is the histaminergic center of the brain?
what does it do?
tuberomamillary nucleus
stimulates arousal by sending axons directly into cerebral axons
what it the role of the lateral hypothalamus in mediating arousal?
promotes arousal - by sending excitatory signals to the tuberomammillary nucleus, which then sends ACh through its cholinergic axons into the cerebral cortex
what is the role of the ventrolateral preoptic nucleus in mediating arousal?
“the masters switch for sleep”
inhibits arousal and promotes sleep - does so by inhibits brain centers that promote cortical arousal (i.e., tuberulomammillary & lateral hypothalamus)
the reticular formation
- is located where?
- has which key nuclei? with what characteristics?
- has what general role?
- located: from spinal cord to thalamus - esp in medulla & pons
- nuclei:
- dorsal tegmenal - cholinergic
- paramedian reticular - dopaminergic
- locus coeurleus - adrenergic
- nucleus raphe pontis & magnus - serotonin
- pontine reticular (oral and caudal) - GABA
- characteristics: highly stellate with long axonal processes
- role: interacts extensively with cranical nerves
dorsal tegmental nucleus releases?
reticular formation nucleus
cholinergic
the paramedian reticular nucleus releases?
(reticular formation nucleus)
dopamine
the locus coreulus releases?
(reticular formation nucleus)
adrenergic NTs
which reticular formation nuclei release serotonin?
- nucleus raphe pontis
- nucleus raphe magnus
which reticular formation nucleus releases GABA?
- oral pontine reticular nucleus
- caudal pontine reticular nucleus
which basal forebrain, thalamus and reticular formation release acetylcholine?
- basal forebrain: basal nucleus of meynert
- thalamus: tuberomammillary nucleus
- reticular formation: dorsal tegmental nucleus
the brainstem is in charge of what major visceral functions?
- hearbeat
- ventilation
- digestive processes
describe the mediation of ventilatory rhythm
- mediated by the brainstem via the following reticular formation nuclei:
- solitary nucleus: mediates inspiration
- nucleus amgiguus: mediates exhalation
- nucleus parabrachialis: mediates transition from inhalation to exhaation
the solitary nucleus
- is located where?
- has what role?
- is regualted how?
- location: reticular formation
- role: stimulates inspiration - by projectiing to phrenic & intercostal nerves
- regulation: is self excitatory (i.e., excited by I neurons)
the nucleus ambiguus
- is located where?
- has what role?
- is regulated how?
- location: reticular fornation
- role: stimulates exhalation -> projects to intercostal nerves
- regulation: is inhibited by I (inspiratory) neurons, which are:
- inhibited by nucleus parabrachialis medialis
the nucleus parabrachialis medialis
- is located where?
- has what role?
- is regulated how?
- location: reticular formation
- role: mediates transition from exhalation to inhalation, by
- exciting E neurons in nucleus ambiguus
- inhibited I neurorons in solitary nucleus,
- which also inhibits inhibition of E neurons
the reticular formation ascending pain pathway
- involves what reticular formation nuclei?
- that recieve what signals?
- that send their projections where?
- leads to what type of pain perception?
- nuclei:
-
the “central group”
- lateral reticular nucleus
- subnuclear reticularis dorsalis
- gigantocellular nucleus*
- receive signals from ascending fibers in the spinal cord
- send projects that disperse widely throughout the cerebral cortex
-
the “central group”
- thus, producing non-locazalized pain that is perceived as general “awareness”
reticular formation pain modulation
- involves what nuclei?
- that receive what sigals?
- that send their projections where?
- nuclei:
- the caudate raphe nuclei
- nucleus raphe obscurus
- nucleus raphe magnus
- nucleus raphe pallidus
- receive signals from the periaqueductal gray matter
- send projections to the
- substantia nigra: dosral horn 2nd order nueoron in spinothalamic tract
- lateral reticular & gigantocellular: reticular formation neurons in ascending pain path
- spinal trigeminal
- the caudate raphe nuclei
- results in modulation of pain
the reticular formation is involved in pain transmision in what two general ways?
- as part of an ascending pain path: leads to general “pain awareness” without localization
- via modulation of other ascending pain paths: spinothalamic, spinal trigeminal, reticular formation
which reticular fomation nuclei are involved in the sleep cycle?
which are involved in:
- maintaining arousal
- promoting REM sleep
- arousal
- nucleus raphes - pontis, dorsalis
- pedunculopontine
- laterodorsal tegmental
- locus coeruleus
- transition to sleep
- sublateral dorsal nucleus
what are the roles are the sublateral dorsal nucleus?
- transition to REM sleep
- promotion of atonia
ascending reticular activating system (ARAS)
- includes what nuclei
- has what role?
- includes
- several same nuclei has the arousal nuclei
- nucleus raphe - dorsalis, pontis
- pedunculopontine
- oral pontine reticular nucleus
- parabrachial nucleus
- several same nuclei has the arousal nuclei
- serve to maintain consciousness
the ARAS projects to what two parts of the brain?
two rostral projections
- hypothalamus (subthalamic)
- thalamus: intralaminar nucleus of the thalamus
disruption of the ARAS can lead to?
- depends on which brainstem level reticular formation disrupted:
- medulla: brain death
- pons, midbrain: coma
the the reticular formation has motor functions via what two pathways?
- reticulospinal
- reticulocerebellar
- reticulospinal
- reticulocerebellar
the reticulopinal pathway
- involves what reticular formation nuclei?
- innervate what targets?
- have what actions:
- two extrapyramidal pathways that innervate postural muscles
- medial (pontine) reticulospinal
- origin: oral & caudal pontine reticular nuclei
- action: LE extension (+ flexion inhibition)
- lateral (medullary) reticulospinal
- origin: gigantocellular nucleus
- action: UE flexion (+extension inhibition)
- medial (pontine) reticulospinal