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1
Q

1-hypothalamus location

2-functions of the hypothalamus

A

1-group of nuclei below the thalamus…together form diencephalon

  • above pituitary
  • –many tracts in betweeen hypothalamic nuclei to the pituitary= interface between neural & endocrine systems

2-primary function of hypothalamus= maintain internal environent of the body (homeostasis)
secondarily= complex emotions & behaviors (as part of limbic)
—hypothalamus connects w/ brainstem to regulate autonomic function,
to the reticular formation in brainstem to regulate arousal,
to the pituitary to regulate neuroendocrine function
& to regions of limbic system to participate in complex emotional & motivational behaviors

2
Q

1-major functions of the hypothalamus

2-circadian rhythms

3-thermoregulation

A

1-homeostasis
circadian rhythms
thermoregulation
regulation of eating & drinking behavior, water balance
regulation of reproduction & sexual behavior
autonomic control
generation & regulation of emotional behaviors

2-suprachiasmatic nucleus of hypothalamus sets rhyhtm—sleep promoting/inhibiting areas. based on eyes w/ the light activates pineal gland for melatonin

3-mammals=homeotherms= internal body temp in narrow range.
temp set= 37=98.6= orally…rectal(core)=.5 higher
hyperthermia=high temp= 41=106: convulsions from CNS and at 43= death
hypothermia=low tem=as temp falls=confusion
28 thermoregulation=los & body temp declines & death will occur

3
Q

1-peripheral thermoreceptors

2-central thermoreceptors

3-stimulated by cold

4-stimulated by heat

5-fever

A

1-cold thermoreceptors in skin, activate posterior hypothalamus

2-thermoreceptors in anterior hypothalamus monitor core temp

3-dec heat loss= vasoconstriction & behavioral (sweaters, thermostat etc)
inc heat production= thyroid hormone/epi & shivering + inc muscle tone

4- inc heat loss= vasodilation, sweating, & behavioral(remove clothes etc)
dec heat production= dec muscle tone, dec thyroid & epi, dec appetite

5-equivalent to changing thermostat setting—inc pyrogens are released (IL 1 & IL6)
when setpoint is reset to normal temp, the fever “breaks”
bc of dec pyrogen release

4
Q

1-hypothalamic regulation of water balance

A

1-thirst= feeling to get you to seek & ingest fluids
thirst center= regulate h20 balance in body, thirst contains osmoreceptor neurons that sense osmolarity of blood passing via hypothalamus
—regulates via osmoreceptors in hypothalamus
osmoreceptors stretch when inc fluid & shrink when little.
—inc excretion when excess h20 ingested
—ADH (vasopressin) produced by hypothalamic peptidergic neurons adjacent to osmoreceptors—terminate in posterior pituitary & released into blood is dec when there is an inc in h20.

5
Q

hypothalamic regulation of feeding

1-feeding center

2-satiety center

Appetite Stimulating

3-neuropeptide y

4-ghrelin

5-orexins (hypocretins)

A

1-lateral (outer) hypothalamus—lesions= anorexia
amphetamines inhibt food intake by enhancing NE & dopamine levels in lateral hypothalamus (feeding center)

2-ventromedial hypothalamus—lesions=hyperphagia

  • no receptors for calories ingested
  • so signals= plasma glucose, temp, GI distension, alteration of peptide hormones

3-in hypothalamus & SNS = feeding stimulus also fat storage, circadian, BP

4-hunger hormone—released by tummy & upper GI in response to weight loss. why its hard to maintain weight loss after dieting, if you have gastric bypass the inc in levels doesnt occur…also released in response to stress (stress eating)

5-neuropeptide released by small number of hypothalamic neurons…promote wakefulness & appetite

6
Q

appetite inhibiting hormones
1-leptin

2-new weightloss drugs

3-limbic system

A

1-manufactured by fat cells that are currently in primary satiety hormone
-acts on receptors in hypothalamus to counteract effects of neuropeptide Y…inhibits orexin release

2-bc of inc obesity these have been made: lorcarserin, phetermine, topiramate, buproprine, naltrexone, & qnexa

3-loop of several structures interconnected—primitive cortex
-portions of cerebral cortex (cingulate & hippocampus), thalamus, hypothalamus, amygdala

7
Q

limbic system functions

1-olfaction

2-feeding

3-reproductive/sexual

4-autonomic regulation

5-learning/memories

A

1-amygdala= emotional response to olfaction

2-lesions of amygdala= non discrim hyperphagia…animal will eat anything, amygdala= chewing, swalloing & licking

3-sensitive to sex steroids.

4-stimulatin of limbic areas initiate response…part of complex emptional & behavioral responses

5-destruction of certain areas in limbic will disrupt short term memories, longterm & learning

8
Q

1-reward

2-punishment

3-emotions

4-inner emotions

5-amygdala

6-emotional behavior

A

1-organism will work for to reinforce good behavior

  • bandof limbix tissue that lines inferior front cortex to midbrain…& nucleus accumbens
  • Dopamine antagonists dec sel stimulation in animals….durgs produce emotional high

2-organism will avoid to dec frequency of behavior
-diffuse…lateral hypothalamus, hippocampus, amygdala, thalamus, & dorsal midbrain

3-complex feeling states that have mental, physical & behavioral components

4-hope, anger, fear—mainly amygdala & higher cortex
-collecton of nuclei between temporal lobe & hippocampus…connects w/ prefrontal cortex & hypothalamus (for balance)

5-acting out or expressions of emotions (crying etc)

hypothalamus= complex bheavior and coordinates area

9
Q

**1-voluntary aspectts of swallowing

2-involuntary aspects of swallowing

3-heterarchichal**

4-why does organization matter

A

1-cortical, subcortical & brainstem level

2-only at brainstem level
—swallowing considered heterarchical

3-system that communicates via multiple, parallel, overlapping loops that give info and send info across & between levels in CNS in bidirectional

4-swallowig disorders manifest neurologically—clinical profile of swallowing w/ neurological etiolgy depends on area of brain
-understanding allows clinician to: predict symptoms of swallowing & speficy diagnosis/treatment plans

10
Q

1-lateralization

2-timing of movements

3-PMC/SMA

A

1-bilateral representation of swallowing…but is assymmetrical
primary laterlization on L. side during initial stages of swallowing w/ shift to R. for later
—insula preferentialy activate on 1 side
—r. hemisphere axtivity
—l. side = bolus prepped, r.side= bolus changes to pharyngeal phase

2-PMC & SMA—ready the system to swallow, oral & pharyngeal phases of swallowing
-poorly coordinated motor aspects of oral prep, transit, & phayngeal phase

3-oral phase disorders= reduced suction bc of poorly coordinated soft palate depression & tongue/facial contraction & buccal tension===no suction to get liquid up via straw…
reduced tongue tip elevation=abnormal bolus hold/spillage
reduced mastication= foods spread throughout cavity
reduced lingual veal contact before pharyngeal trigger= premature spillage

-pharyngeal phase disorders= generalized=poor cooridnation of tongue & phayrngeal wall movement= left over residue throughout pharynx

  • –aspiration= food/liquid into airway
  • –mastication= bolus spread out (obstructing airways)
11
Q

1-primary motor cortex

2-primary somatosensory cortex

3-lesion of primary somatosensory cortex

A

1-online control of motor comp of oral prep, transit & pharyngeal phases —moving hot soup around mouth

  • control the duration & intensity of oral prep, transit & pharyngeal phase —bolus larger than anticipated
  • manifestations= affect strength & timing of movement during oral prep

2-priming to trigger pharyngeal swallow

  • receives info to regulate motor of swallowing
  • reduced sensory processing affected the phases
  • delayed trigger pharyngeal swallow DTPS= aspiration before swallow
  • dec responsiveness to residue= aspiration after swallow

3-water will fall into airway & aspirate before you swallow

12
Q

1-Somatosensory & Sensory Association Areas

2-residue will be aspirated

3-insula

4-thalamus

5-thalamocortical

A

1-regions as centers responsive to tactile/chemical stimulation
-modulates strenght & timing of swallow
-clinically= reduced sensory affecting pharyngeal phase & responsiveness to thermal
-possible disorders=
delayed trigger of pharyngeal swallow= pooling over tongue base, aspiration before swallow
dec. responsibeness to residue= aspiration of residue after swallow

2-unless you respond to residue, but if you dont responsd to pharyngeal residue= rlesion of primary somatosensory cortex/sensory assc areas

3-structure of brain that helps process taste info & ready pharyngeal swallow

  • higher order movement
  • Delayed trigger of swallow DTPS=focal infarct of anterior insula (r. hemispheric)
  • Reduced taste gustator processing DTPS= aspiration after the swallow (not silent) if affected by insula—geriatric patients

4-checkpt for sensory info

5-afferents travel up through internal capsule to get to primary somatosensory cortex, end of pathway

  • reduced responsiveness to oral residue= asipiration before swallow
  • DTPS= absent responsibeness to residue
13
Q

1-subcortical neurophys-Basal Ganglia

2-parkinsons

3-cerebellum

4-brain stem CPG

**5-CPG controls & info processing

6-sensory & motor nucleus**

A

1-sensory & motor fibers moderate sensorimotor feedback

  • lesion on focal l. basal ganglia= longer pharyngeal transit time & delaye times bc of thicker boluses
  • low dopamine levels= silent aspiration
  • aspiration pneumonia= 2x in hemispheric CVA and 3x when BG infarct= bilateral
  • bolut formation=reptitive up & back movement of central portion of tongue

2-rocking/rolling of bolus
reduced sensory integration
silent aspiration
lead to aspiration pneumonia
dont know its happened

3-acquire, process & use sensorimotor info
-priming & swallowing
lesions= discoordinated, & reduced priming

4-mediates involuntary preprogrammed pharyngeal phase

  • bilateral —controls program for activation of muscles & sensory
  • modulated but not controlled by cortical/subcortical

5-controls swallowing
&&& info is processed in the medulla of brainstem

6-sensory= nucleus tractus solitarus NTS 
motor= nucleus ambiguous NA

sensory from anterior faucial pillars trigger phrayngeal swallow—> goes to NTS in medulla—>interneuroons share message w/ NA in medula—> sends preprogrammed motor company to execute

14
Q

1-specific to swallowing

2-vagus

3-trigeminal

4-facial

5-glossopharyngeal

6-vagus

7-hypoglossal

A

1-trigeminal (V), facial (VII), Glossopharyngeal (IX), Vagus (X), Hypoglossal (XII)

2-safety standpoint/checkpoint

3-ORAL PHASE—motor=mastication
sensory= thermal, tactile & pressure
reduced mastication= food spreads and falls

4-ORAL PHASE—motor oral glands for saliva
sensory= taste for anterior 2/3 & soft palate
-reduced saliva, inability to suck etc
-reduced labial closure, rounding & suction

5-PHARYNGEAL PHASE—motor-innervates stylopharyngeus (allows food to go through pharynx)
sensory-posterior 1/3 tongue taste
-dec laryngeal elevation= aspiration or residue

6-motor= soft palate, pharynx & larynx
sensory= somatic sensations from soft palate, pharynx & larynx

7-ORAL & PHARYNGEAL PHASE-motor of intrinsic & extrinsic tongue

15
Q

1-trigem neuralgia

2-root cause of trigem neuralgia

3-intracranial tumor

4-demyelination…

5-trigger pts

A

1-neuropathic pain, in gasserian ganglion of V
-post traumatic neuralgia, post herpetic neuralgia & diabetic neuropathy
-pain= excruciating & unilateral
-2nd & 3rd divisions= commonly affected.
R. side> left.
Females> Males

2-A-delta fiber dysfunction from demyelination in gasserian gang—demyelination= pressure from an artery above ganglion, direct trauma, or from de-myelinating disorder (MS)

3-can also put pressure on gasserian gang= de-myelination—the attacks may be unrelenting

4-w/ the insulation removed, spontaneous discharges occur in ganglion= cascading effect of pain from sec to min—w/ dull aching after

5-specific area on face that are even lightly touched may trigger an attack—wind, H20= provoking
cant shave his face
-allodynia= altered sensation on skin is present

16
Q

1-pre-trigem neuralgia

2-mimicry

3-diagnostic hints

4-tx

5-medications

A

1-may exist for mo. or yrs. before attacks begin
-toothache or sinusitis, jaw movements drinking hot and cold

2-trigem neuralgia or pretrigem may mimic odontogenic pain to point that entire quadrants have root canals, only to have pain move from tooth to tooth & remain …after extractions= pain remains

3-pain from normal tissue

  • prior diagnosis of TN or MS
  • pain= shocking, burning, stabbing
  • trigger pts or allodynia
  • multiple dental procedures w/ no effect

4-medication, partial/purposeful damage to gasserian ganglion & surgery

5-antiseizure drugs= most effective for alleviating symptoms of trigem neuralgia= Na channel blockers

  • tegratol= gold standard
  • baclofen
  • dilantin
17
Q

1-purpose damage to gasserian

2-surgery

3-techniques

4-TMJ innervated by

5-same sensory fibers innervating a joint

6-trigem sensory nuclei

7-misdiagnosis

A

1-damaging w/ alc injection or heat reduces discharge rate & pain produced

  • like anesthesia
  • radio partial ablation of nerve w/ radioactive cobalt= common—area of gang targeted & exposed for a few min & effective for 6 mo to several years
  • cutting nerve isnt done

2-vascular decompression surgery= done in cases where its been determined that sagging artery is responsible for neuralgia—foam pad between ganglion & offending artery

3-all have favorable prognosis w/ medications
200 k suffer
12/100k new cases a year
if not treated quickly then suicide rate inc

4-posterior 2/3 by auriculotemporal
anterior 1/3 by masseteric

5-also innervate muscles that pull over joint

6-large & synapses…may communicate w/ synpases from nearby structures= referred pain phenomenon

-pain from joint may be felt other areas (teeth)

7-innocent symptomless joint click w/ muscle pain=referred to joint= unneeded surgeries

18
Q

anatomy of the eye

1-cornea

2-sclera

3-lens

4-uvea
a-choroid
b-ciliary body
c-iris

A

1-transparent…densely innervated tissus for pain fibers—cornea= avascular, receive nutrition via diffusion

2-covers posterior 4/5 of eye= opaque & collagent & elastic fibers in irregular bundles
—1&2= outermost CT layer

3-avascular, biconvex lying posterior to iris

  • suspended from ciliary body by zonular fibers (suspensory)…zonular help maintain ellipsoidal shape of lens…
  • thickness of lens= controlled by action of muscles in ciliary bdoy

4-considered middle layer of eye= vascular

a-thin layer of CT w/ specialized network of large capillaries

b-circumferential structure attached to lens by suspensory ligaments & have ciliary for lens accomodation

c-pigmented disc w/ central pupil
has SM fibers that regulate size of pupil & amt of light that reaches retina
-sphincter pupillae muscle= ring shaped & on pupillary margin—innervated by parasymp fibers from ciliary gang & contraction of muscle constricts pupil (miosis)
-dilator pupillae = collection of radially SM fibers
-innervated by symp fibers from superior cervical gang & contraction of muscle enlarges pupil (mydriasis)

19
Q

1-retina

cell types in neural retina
2-retinal pigment epithelium RPE

3-photoreceptors

4-biplar cells

5-horizontal & amacrine cells

6-muller cells

7-ganglion cells

A

1-delicate, transparent tissue that covers inner surface of posterior wall of globe—outgrowth of diencephalon

2-single layer of cells whos basal surface is in contact w/ choroid & apical surface in contact w/ photoreceptors

3-rods & cones—constitute light sensitive neurons of retina w/ shapes characteristic of names
rods vs cones= 20: 1…rods sensitive to low light= night vision…cones= sensitivity (blue, green, red) & differential stimulation of 3 sets of cones in ability to see color

4-get info from rods & cones & axon of bipolar cell synapses w/ ganglion cell

5-retinal association neurons…modify visual data from photoreceptors to enhance borders & contours & inc contrast

6-extend through all portions of retina…function like oligodendrocytes & provide metabolic support for retinal cells

7-last link in retinal component of visual pathway…receive info from bipolar cells & each gang axon joins other gang axons===optic nerve

20
Q

1-regional distribution of rods & cones

2-macula lutea

3-optic disc or papilla

4-chambers

A

1-rods are absent from central fovea & inc in # towards peripheral retina. cones= densely packed in central retina & dec in # rapidly in all peripheral directions

2-small, pale yellow, circular area & posterior pole of globe—direct line w/ visual axis= central vision

  • gaze @ fixation in center of visual field= maculae of both retinas
  • in center of macula lutea= shallow depresseion= fovea centralis—area for harpes= vision & acute color discrimination
  • all retinal layers are displaced laterally so light passes directly to layer of photoreceptors
  • fovea only has cones

3-medial to posterior pole of retina

  • exit of optic nerve fibers—lacks photoreceptors= blind spot.
  • ophthalmic BV enter & exit eye at this site= pale pink

4-lens, suspensory ligaments & ciliar bodys partition eye into posterior (large) & anterior (small)

  • iris divides anterior into anteiror & posterior chambers
  • posterior= gelatinous vitreous humor—not replenished
  • anterior= watery aqueous humor—continually replaced
21
Q

1-visual field

2-fixation pt

3-visual field vs retinal fields

4-light path through retina

A

1-what is visible to an individual when eyes are fixed on an object in direct line of vision…each eye has own visual field & is tested separately

2-looking straight ahead, center of visual field w/ image transmitted to fovea of both retinas

  • –imaginary line drawn vertically through fixation pt divides visual field into nasal & temporal halves
  • –imaginary line drawn horizontally further divides into upper & lower quadrants

3-each retina can be divided into nasal & temporal halves & upper/lower quads. bc light travels in straight line, there is an inverse relationship between visual & retinal fields. image in visual= inverted & reversed onto retina

4-light goes through transparent cornea, anterior compartment, through lens & vitreous body & retinal layers…then light energy converted to electrochemical signals by visual transduction. synaptic connections send signal from photoreceptors to bipolar cells to ganglions cells. axons exit eye at optic disc

22
Q

1-optic nerve/chiasm

2-optic tract, lateral geniculate nucleus & extra geniculate projections

3-geniculocalcarine tract (optic radiations)

A

1-retinal ganglion cell axons form optic nerve…just after entering cranial cavity, optic nerve unite to form optic chiasm & undergo partial decussation
-fibers from temporal visual fields (nasal retinae) cross to opposite side…net of partial decussation= entire l. field of vision projects to r. side of brain & r. field of vision goes to l. side of brain

2-after going through chiasm, fibers go to tract
80% go laterally/caudally to synapse in LGN of thalamus
20% enter branchium of super colliclus, paratexta for visual reflexes…& superchiasmatic nucleus of hypothalamus for day/night cycle

3-axons of LGN leave LGN to form geniculocalcarine tract

  • fibers carrying info from upper visual fields pass anterior, loop down & forward into temporal lobe…pass superior & lateral to inferior horn of lat. ventricle before going posteriorly as ventral portion of optic radiations
  • fibers carrying info from lower visual field= direct anteroposterior course through parietal lobe & occupy dorsal portion of optic radiations
  • fibers w/ info from macula (central) occupy intermediate of optic radiations
23
Q

1-striate cortex (primary visual cortex)

2-visual association cortices

A

1-incoming LGN axons term in layer 4 of 6= white line (line of gennari)
-fibers from upper visual= to cortex inferior to calcarine sulcus
-fibers from lower visual= to cortex superior to caclarine sulcus
-fibers from macular= to caudal of straite cortex, while fibers from successively peripheral regions term in anterior regions
-amt of cortical area devoted to unite area of sensory surface (retina) isnt uniform—reflects density of receptors…cortical representation of fovea= very large & takes up most of caudal pole of occipital lobe
peripheral retinal areas= much smaller

2-multiple areas in occipital, parietal & temporal, process visual

  • ventral path from striate to temporal lobe…high res vision & object recognition
  • dorsal path form striate to parietal…spatial aspects of vision—analysis of motion & positional relationships between objects in visual field
24
Q

1-pupillary light reflex

2-near (accomodation-convergence) reflex

3-argyll robertson pupil

4-ARP & PRA

A

1-protexting retina from lots of light—light of 1 eye= bilateral constriction of pupils…illuminated eye= direct response & contralateral eye= consensual response

  • –Afferent limb of reflex= retinal relays from photoreceptors to bipolar to ganglion, before reaching LGN, collaterals of gang axons enter brachium of superior colliculus & term in pretectal
  • –associational limb of reflex= cells in pretectal nucleus sends axons to both EW…deccusates in posterior commissure
  • –efferent limb= cells in EW send axons via oculomotor to postgang neurons in ciliary gang…ciliary gang innervate sphincter pupillae w/ bilateral constriction of pupils
  • –evaluation of pupillary light reflex during neuro exam= lesion of afferent (optic nerve)= light in affected eye shows no response in either eye…light in healthy= pupillary constriction
  • –lesion of efferent (oculomotor)= affected eye shows no direct/consensual response to pupillary light reflex—healthy shows direct & consensual response

2-brains sees an out of focus object & reflexively brings it into focus…tests change in focus from far to near= ocular convergence, lens thickening & pupil constriction

3-pupil that is small, irregular, & fixed to light (no light reflex) but constricts to accomodation (near reflex present)…lesion in pretectum is presume bc of neurosyphilis

4-accomodation reflex present
pupillary reflex absent

25
Q

1-animals smell vs humans smell

2-anosmia

3-olfactory mucosa

4-olfactory bulbs

A

1-macrosmatic vs microsmatic

2-loss of sense of smell= impairment of taste

3-in superior posterior part of nasal cavity…columnar epithelium surround olfactory neuroreceptors—only neurons to comm w/ external environ & be replaced

  • basal cells near lamina propria differentiate & develop into neurons every 5-8 wks
  • –bipolar olfactor neurons have 1 dendrite that project towards apical mucosa—term end of dendrite flattened and have cilia…cilia have receptors
  • unmyelinated axons (slow conduction) of bipolar= olfactory nerve…pass from nasal cavity to interior of brain via foramina in cribriform plate of ethmoid to term in bulbs

4-flattened ovoid body on cribriform plate of ethmoid

  • first processing of olfactory info, gets input from nerve & has second order neurons= mitral cells
  • axons of mitral make up olfactory tract
26
Q

1-olfactory tract

a- medial olfactory stria
b-lateral olfactory stria
c-intermediate olfactory stria

2-primary olfactory cortex

A

1-prom fiber tracts from olfactory bulbs that course posteriorly towards anterior perforated substance
at anterior perforated substance-splits into 3

a-few fibers in it—project to septa area & contineu through MFB to hypothalamus, thalamus, hippocampus & upper brainstem

b-majority of fibers of olfactory tract & carries to piriform cortex, periamygaloid cortex, corticomedial portion of amydale

c-small contingent fibers entering perforated-unknown

2-lateral olfactory gyrus= thin layer of gray matter overlying lateral olfactory stria
-small portion of uncus= preperiform cortex & periamydaloid cortex
-POC projects to amygdala & olfact. association cortex
-olfactory association cortex=
anterior of parahippocampal
region= entorhinal cortex
-
entorhinal= heavy projections to hippocampal formation…allowing olfactory into limbic
-together the primary (prepiriform) & association (entorhinal) ===piriform cortex/lobe/area

27
Q

1-taste

2-sweet

3-salt

4-sour

5-bitter

6-receptors

7-fungiform & filliform papillae

8-foliate papillae

9-circumvallate papillae

A

1-taste receptors in oral cavity—unlike olfactory, taste receptors are specialized epithelial cells in touch w/ peripheral nerve fiber
-flavor= combo of taste sensations & aromas

2-taste receptors at tip of tongue

3-taste receptors along sides of tongue

4-taste receptors along side of tongue

5-taste receptors on posterior of tongue

6-receptors in taste buds on surface of tongue…each bud= 40-60 receptors

  • apical ends of receptors into taste pore
  • sensory fibers attach to basal surface of receptor cells
  • taste receptor cell has life span of 1-2 wks—replaced by differentiation of basal cells
  • distributed on dorsal of tongue but also on palate & pharynx

7-anterior 2/3 of tongue

8-lateral margins of tongue

9-v-shaped line 2/3 way back on dorsum of tongue

28
Q

peripheral pathways of taste
1-CN 7

2-CN 9

3-CN 10

central structures

5-solitary tract

A

1-facial= chorda tympani carries taste from anterior 2/3 of tongue—cell bodies in geniculate ganglion

2-glossopharyngeal= carry taste from posterior 1/3
cell bodies in inferior glosso (petrosal) ganglion

3-vagus= superior laryngeal carries taste from epiglottis—cell bodies in inferior vagal (nodose) gang

4-enter brainstem—once there will enter solitary tract

5-carries taste of CN 7, 9, 10 to nucleus of tract
-in medulla fibers of solitary tract are surrounded by nucleus of solitary tract (bulls eye) and enter & term in nucleus

29
Q

Central Structures

1-nucleus of solitary tract (NTS)

2-thalamic neurons

3-taste cortex

A

1-principal visceral afferent nucleus in brainstem
—gets not only taste (special visceral afferent SVA) but also general visceral afferent (GVA) inputs from CN 9 & 10
—NTS: Caudal= GVA inputs Rostral= SVA inputs
*rostral= gustatory nucleus
-NTS= 2nd order neurons in ascending taste path—axons will ascend to VPM thalamic nucleus ipsilaterally in central tegmental tract

2-VPM nucleus gets inputs from ipsilateral NTS

  • 3rd order neurons in ascending taste pathway located here
  • projects to ipsilateral taste cortex

3-considered to be insular cortex & medial aspect of frontal operculum
-projects to orbital cortex & amygdala for higher integration of taste info

30
Q

1-organizaiton of eat

ANATOMY

2-cochlea

3-cochlear duct

4-boundaries
a-roof
b-lateral wall
c-floor

A

1-tonotopic organization through entire pathway

2-part of bony labyrinth= bony tube that goes spirally 2 3/4 turns around modiolus bone

3-part of membranous labryrinth. enters cochlea & attached at each edge to 2 side

  • divides cohclea into 2 long chambers
  • -scala vestibuli= above duct & scala tympani=below
  • –both comm w/ each other at apex of modiolus via helicotrema & both filled w/ perilymph

4a-vestibular membrane (reissners)

4b-spiral ligament…thickening of endosteum that lines cochlea—uper part of spiral= stria vascularis, highly vascularized epi that produces endolymph
-cochlear duct= filled w/ endolymph

4c-basilar membrane that stretches from spiral ligament to osseous spiral lamina…lamina= bony plate that winds around modiolus like the threads of a screw

  • osseous spiral lamina= composed of 2 thin plates of bone, between which are canals for transmission of nerve fibers
  • periosteum of upper surface of osseous spiral lamina= elevation= spiral limbus
  • tectorial membrane= thin, jelly membrane arises from spiral limbus & over hair cells of organ of corti (organ ontop of basilar membrane)
31
Q

1-organ of corti

2-spiral ganglion

3-cochlear n

A

1-complex epi structure of neuroepi hair cells

  • neuroepi hair cells in rows, inner hair cells form a single row w/ 3-5 rows of outer hair cells
  • free surfaces of hair cells covered w/ sterocilia but no kinocilium…stereocilia touch, embedded in, tectorial membrane
  • base of each hair cell is contacted by afferent & efferent nerve endings

2-located w/in modiolus of cochlea—30k bipolar neurons

  • 90% innervate inner hair cells w/ 1 fiber innervating 1 inner hair cell getting 10 fibers…innher hair tuned to specific tune
  • 10% inenrvate outer hair w/ 1 fiber innervating many outer. outer also get olivocochlear synapses = fine tuning aural input

3-central processes of spiral gang form cochlear nerve—primary afferent fibers make up cochelar n. bifurcate prior to term in cochlear nuclei…1 collateral term in ventral cochlear nucleus & other collateral bifurcates once more to term in ventral cochlear nucleus & dorsal cochlear nucleus= 3 branches from primary afferent fiber

32
Q

1-auditory pathway

2-mechanism of activation

A

1-transduction through middle air…airborn sound waves strike tympanic membrane which vibrates in response—vibrations are transmitted across cavity via 3 bony ossicles

  • foot plate of stapes moves to & from (door opening & closing) in oval window, transmitting vibration to fluid filled inner ear
  • pressure from compression of perilymph is released via round window

2-pressure waves begin in perilymph from oscillations of foot plate of stapes—pressure waves enter scala vestibuli & via helicotrema…transmitted to scala tympani

  • pressure waves transmitted through endolymph of cochlear duct making basilar membranes vibrate
  • basilar membranes are narrow & taut near base of cohlear…vibrates to sounds of high pitch &
  • basilar membranes that are wide & floppy near apex of cochlear vibrates to low pitch…between apex & base= continuous resonance
  • oscillations of basilar membranes alter conformation between hair stereocilia & tectorial membrane—deformation of hair cells cause alteration of discharge in contacting afferent fibers
33
Q

1-action potentials

central connections

2-dorsal & ventral cochlear nuclei

3-acoustic striae

A

1-generated in activated spiral ganglion cells w/ action potential propagated along central processes of bipolar neurons…=cochlear n. once it exits modiolus it goes through internal acoustic meatus w/ vestibular comp of CN 8 and enters brainstem at pontocerebellar angle

2-in dorsal & lateral to inferior cerebellar peducle
tonotopically

3-fibers in all 3 striae cross midline to enter contralateral lateral lemniscus—some go bilaterally to superior olivary

  • axons from dorsal cochlear form dorsal acoustic stria and go to lateral lemniscus
  • axons from posterior of ventral form intermediate acoustic—main branch= lateral lemniscus…collaterals go bilaterally to superior olivary
  • axons from anterior portion of ventral form trapezoid body & is largest & most imp…collaterallys go pilaterally to superior olivary
34
Q

1-superior olivary

2-lateral lemniscus

3-nucleus of lateral lemniscus

4-inferior colliculus

5-medial geniculate nucleus MGN

6-prim auditory cortex

7-auditory association cortex

A

1-in caudal pons has medial & lateral superior olivary nucleus & nucleus of trapezoid body

  • first pt in path where input from both side converge
  • cells are sensitive to differences in time of arrival of sound—so function in localizing sound in space
  • cells in superior olive send axons bilaterally to lateral lemnisci

2-get 2ndary fibers from contralateral cochlear nuclea via acoustic striae & tertiary fibers from ipsi& contralateral superior oliv…
in lateral pons
-some fibers enter nucleus of lateral lemniscus
-some enter reticular formation to be a part of reticular activating system
-some enter inferior colliculus

3-comm w/ 1 another via commissure & send axons to ipsilateral inferior colliculus

4-in caudal midbrain. gets afferents from ipsilateral lateral lemniscus, bilateral superior oliv & contralateral cochlearn nuclei
-sends fibers to opposite inferior colliculus via commissure of inferior colliculus & to ipsilateral medial geniculate nucleus of thalamus via brachium of inferior colliculus

5-in caudal & ventral thalamus. project ipsilateral primary auditory cortex via sulenticular of internal capsule

6-deep in lateral fissure—transverse temporal of heschl…41 42. tonotopic

7-in posterior 2/3 of superior temporal gyrus 44 22
like wernickes area

35
Q

1-descending auditory pathways

A

1-feedback connections at every level of auditory system—
-oliviocochlear bundle= most important of feedback
-comes from nuclei near superior olive—axons leave brainstem in vestibular division of CN 8, crossing over into cochlear in internal acoustic meatus
-axons term on hair cells in organ of corti
-pre & post synaptic inhibition inhibs all hair cells except those in region of maximal basilar displacement
===auditory sharpening = suppress background noise

36
Q

1-conduction deafness

a-otosclerosis

b-other

2-sensorynearal deafness

a-causes

3-anacusis

4-hypacusis

5-prebycusis

A

1-sound vibrations dont reach oval window
-shouldnt result in ipsilateral deafness bc sound waves can still be transmitted via temporal bone to activate cochlear hair cells—patients hear better by bone conduction (vibrations of temporal) than by normal route of air conduction

1a-cause of conduction deafness bc of fixation of foot plate of stapes

1b-otitis media (inflam of mid. ear), excess cerumen (wax) or foreign material

2-disease of cochlear, cochlear of CN 8 or cochlea nuclei of medulla

2b-prolonged exposure to loud noise
toxic effect from pharmaceuticals= aminoglycosides, aspirin, quinine & streptomucin
-acoustic neuroma= benign growth impeding transmission
-various disease entities= diabetes, rubella, CMV, syphillis, menieres

3-absent hearing

4-reduction in hearing

5-hearing loss associated w/ aging
-most common cause of hearing loss= gradual, bilateral loss w/ high frequency tones lost first (basal cochlea)