Neuro Block 2

Front 1

Spinal cord arterial supply

Back 1

Anterior and posterior spinal arteries (from vertebral arteries); radicular arteries (from segmental vessels)

Front 2

Spinal cord length

Back 2

Extends from medulla at foramen magnum to lower border of first lumbar vert

Front 3

Spinal cord enlargements

Back 3

cervical (upper extremity innervation) and lumbar ( lower extremity innervation)

Front 4

conus medullaris

Back 4

conical termination of the sacral spinal cord, btw L1 and L2

Front 5

filum terminale

Back 5

a condensation of pia mater from the conus medullaris to the coccygeal ligament

Front 6

cauda equina

Back 6

large number of lumbosacral roots surrounding filum terminale

Front 7

Spinal nerves

Back 7

each (except C1) innervates a single dermatome; 8 cervical, 12 throacic, 5 lumbar, 5 sacral, 1 coccygeal

Front 8

Spinal cord internal structure

Back 8

white matter (axons and glia) surround H-gray matter (neuronal cell bodies and glia) with central canal (CSF) in middle

Front 9

White matter subdivisions

Back 9

posterior funiculus, lateral funiculus, anterior funiculus

Front 10

Posterior Funiculus

Back 10

ascending somatosensory fibers ( fasiculus gracilis: sacral and lumbar info/medial; fasiculus cuneatus: thoracic and cervical info/lateral)

Front 11

Lateral funiculus

Back 11

descending tracts to the spinal cord (lateral coritcospinal tract, rubrospinal tract, etc) and ascending tracts from cord (lateral spinothalamic, post spinocerebellar, etc)

Front 12

Anterior funiculus

Back 12

smaller ascending and descending tracts; crossing of spinothalamic tract

Front 13

Gray matter subdivisions

Back 13

dorsal, ventral and lateral horns

Front 14

Dorsal horn

Back 14

sensory (receives sensory input; mediates synapses; neurons give rise to ascending efferent pathways)

Front 15

Ventral horn

Back 15

motor (houses alpha and gamma motoneurons and interneurons; neurons innervate extrafusal and intrafusal muscle fibers)

Front 16

Lateral horn

Back 16

intermediolateral cell column from T1-L2/3 only; thoracolumbar sympathetic outflow

Front 17

Rexed lamination

Back 17

subdivides gray matter into 9 cellular laminae plus an area X surrounding central gray

Front 18

Primary sensory afferent inputs and spinal cord

Back 18

Receives them from dorsal root ganglia at each segmental level and relays them to the brain stem, cerebellum, or thalamus (may or may not synapse in cord first)

Front 19

Alpha and gamma motoneurons

Back 19

housed in spinal cord; innervate extrafusal and intrasfusal muscles respectively of body and extremities

Front 20

Intermediolateral cell column

Back 20

from T1-L2/3; gives rise to pregang sympathetic fibers which synapse in the paravertebral and prevertebral ganglia

Front 21

Preganglionic parasymp neurons in S2-4

Back 21

housed in spinal cord; fibers synapse in terminal ganglia within walls of pelvic viscera

Front 22

dorsal root lesion (dorsal rhizotomy)

Back 22

hypesthesia or anesthesia

Front 23

ventral root lesions

Back 23

may lead to complete flaccid paralysis and atrophy of muscles; involvement of autonomic pregang fibers may result in autonomic dysfunction

Front 24

spinal cord transection

Back 24

destruction of ascending and/or descending tracts produces sensory motor or mixed deficits

Front 25

spinal cord hemisection

Back 25

Brown-Sequard syndrome: loss of fine touch/vibration/proprioception ipsilaterla and below lesion; loss of pain/temp contralateral to and below lesion; spastic paralysis ipsilateral to and below lesion

Front 26

brainstem from rostral to caudal

Back 26

midbrain-pons-medulla

Front 27

Integrative functions of the brainstem

Back 27

nuclei regulate consciousness, motor, respiratory, and cardiovascular activity via reticular formation in core

Front 28

conduit functions of brainstem

Back 28

ascending sensory tracts and descending motor tracts pass through brainstem

Front 29

cranial nerve functions of brainstem

Back 29

cell bodies of cranial nerves are located in brainstem; CN nuclei arranged in funcitonal columns

Front 30

CN functional columns from medial to lateral

Back 30

somatic motor, brachial motor, visceral motor, visceral sensory, somatic senosry, special sensory

Front 31

Somatic motor CNs

Back 31

innervate skel muscles in head and neck that are derived from myotomes (CN III, IV, VI, XII)

Front 32

BRachial motor CNs

Back 32

innervate skel muscles derived from brachial arches: mm of mastication, facial expression, pharynx, larynx, middle ear, trapezius (CN V, VII, IX and X, XI)

Front 33

Visceral motor CNs

Back 33

pregang parasymp innervation to cardiac m, smooth m, glands (CN III, VII, IX, X)

Front 34

Visceral sensory- special CNs

Back 34

taste (CN VII, IX, X)

Front 35

Visceral sensory- general CNs

Back 35

control of cardiorespiratory and digestive fucntions (CN IX and X)

Front 36

Somatic sensory CNs

Back 36

convey touch, pain, temp, position and vibration from skin/muscles/joints of head (CN V, VII, IX, X)

Front 37

Special sensory

Back 37

hearing and balance (CN VIII)

Front 38

Midbrain topography

Back 38

Tectum= colliculi and CN IV; cerebral aqueduct; anterior= cerebral peduncles, CN III

Front 39

Rostral midbrain

Back 39

cerebral aqueduct, periaqueductal gray, sup colliculi, oculomotor nucleus, Edinger-Westphal nucleus, red nucleus , corticospinal tract (middle of crus cerebri), medial lemniscus, spinothalamic tract

Front 40

caudal midbrain

Back 40

cerebral aqueduct, peraqueductal gray, inf colliculi, trochlear nucleus, mesencephalic nucleus of CN V, corticospinal tract, medial lemniscus, spinothalamic tract

Front 41

Pons topography

Back 41

Cerebllar peduncles on posterior surface; basilar sulcus for basilar a, CN V in middle, CN VI, VII, VIII at bottom

Front 42

Medulla topography

Back 42

gracile and cuneate tubercles, corticospinal tract (pyramids), CN IX, X and XII emerge from ant sulci

Front 43

Posterior Cerebral A and superior cerebellar a

Back 43

supply lateral aspects of midbrain including corticospinal tract (middle of crus cerebri)

Front 44

occlusion of PCA

Back 44

Weber's syndrome

Front 45

Basilar and posterior communication aa

Back 45

supply medial aspect of midbrain

Front 46

Lateral aspect of rostral pons

Back 46

superior cerebellar a; basilar a--> short circumferential branches

Front 47

occlusion of superior cerebellar a

Back 47

lateral pontine syndrome

Front 48

Penetrating branches of basilar (paramedian arteries)

Back 48

supply medial pons inc pontine nuclei, medial lemniscus, and corticospinal tract

Front 49

occlusion of basilar a

Back 49

medial pontine syndromes

Front 50

Pontine tegmentum and dorsolateral quadrant of pons blood supply

Back 50

AICA, long circumferential branches of the basilar, and superior cerebellar a

Front 51

occlusion of AICA

Back 51

lateral pontine syndrome

Front 52

lateral aspects of rostral medulla blood supply

Back 52

vertebral a and PICA

Front 53

occlusion of vertebral a/ PICA

Back 53

lateral medullary syndrome (of Wallenberg)

Front 54

medial aspects of rostral medulla blood supply

Back 54

(inc corticospinal tract) anterior spinal a and penetrating branches of the vertebral a

Front 55

occlusion of ant spinal a and penetrating branches of vertebral a

Back 55

medial medullary syndrome

Front 56

posterior spinal artery

Back 56

supplies lateral aspect of caudal medulla

Front 57

medial aspects of caudal medulla blood supply

Back 57

(inc coritcospinal tract) ant spinal a and penetration branches of vertebral a

Front 58

role of somatosensory system

Back 58

allows us to sense touch, temp, proprioception, and pain

Front 59

Basic pathway for sensory stimula to be perceived

Back 59

stimulus> sensory receptors>spinal cord>medulla/brainstem>thalamus>cortex

Front 60

dorsal root ganglion

Back 60

cell bodies of sensory neurons; innervating neck on down; pseudounipolar cell bodies with peripheral and central processes

Front 61

Exteroreceptive sensory receptors

Back 61

code info from external world mainly via skin; inc mechanoreceptors (touch), thermoreceptors, nociceptors (sharp and burning pain)

Front 62

Proprioceptive sensory receptors

Back 62

code info about muscle length/tension and joint angles via muscle afferent receptors (golgi tendon organs and muscle spindles) and joint and tendon afferents

Front 63

Interoceptive sensory receptors

Back 63

code info about changes insid eht body; visceral afferent receptors; localize sensation and pain very poorly

Front 64

sensory neuron stimulus transduction

Back 64

stimulus activates receptors and ion channels> generates receptor potenital> if strong enough, generates APs> APs conveyed to spinal cord

Front 65

Intensity of stimulus is encoded by:

Back 65

each neuron: freq of AP firing (rate code) and many neurons: number of neurons fighting (spatial summation code)

Front 66

A-alpha fibers

Back 66

large, myelinated, conduct APs fast; muscle spindles

Front 67

A-beta fibers

Back 67

large, myelinated, conduct APs fast; light touch, vibration, pain

Front 68

A-delta fibers

Back 68

thin, myelinated, conduct APs moderately fast; nociceptors (fast pain) and cooling receptors

Front 69

C fibers

Back 69

unmyelinated, conduct APs slowly; nociceptors (slow pain) and warm receptors

Front 70

Compound action potential (whole peripheral nerve)

Back 70

clinical diagnostic to determine whether axons are missing, damages or demyelinated; used to diagnose peripheral neuropathies

Front 71

Slowly adapting receptors

Back 71

respond best to sustained, unchaning stimulus; sense pressure and shape of objects

Front 72

Rapidly adapting receptors

Back 72

respond only when stimulus changes (on/off); sense impact and motion of objects on skin

Front 73

Superficial receptors receptive field size

Back 73

small receptive field size

Front 74

Deep receptors receptive field size

Back 74

large receptive field size

Front 75

Innervation density

Back 75

high in very sensitive areas (fingers, face) low in insensitive areas (back, calves) using 2 point discrimination

Front 76

mechanoreceptors

Back 76

mediate tactile/touch; very senstive to force (low threshold); silent without stimulation' myelinated axons, fast conduction

Front 77

Merkel disks

Back 77

fine touch- sharpest resolution of surface texture; @ epidermal/dermal junction; multiple small spots for receptive field; several innervated by single myelinated axon; slowly adapting, encodes amount of force

Front 78

Meissner's corpuscles

Back 78

fine touch; epiderm-dermal junction; single spot receptive field; corpuscle closes stack of flattened epith cells; myelinated axons; rapidly adapting response encodes on/offset of skin indentation

Front 79

Ruffini Endings

Back 79

in dermis; sense stretch to determine shape; large and diffus receptive field; encapsulated ending; myelinated axons surrounds collagen fibrils; slowly adapting

Front 80

Pacinian corpuscles

Back 80

in dermis; high freq vibration; most sensitive mechanoreceptor, even distribution; large and diffuse receptive field; fluid filled capsule; myelinated axon; rapidly adapting

Front 81

Meissner's vs Pacinian

Back 81

Meissners: low freq vibration and lots of indentation to be activated
Pacinian: high freq vibration and only require tiny amounts of skin indentation

Front 82

Hair follicle receptors

Back 82

respond to movement of hairs; receptive field around base of hair follicle; bare axon wraps base of follicle, axon is myelinated; rapidly adapting response to encode velocity of hair movement

Front 83

best at 2 point discrimination

Back 83

Merkel (Meissner's is ok)

Front 84

Thermoreceptors

Back 84

encode skin temp; discharge continuously at normal skin temp

Front 85

cooling receptors

Back 85

increase firing rate when skin is cooled; stop firing when warm; free nerve endings with myelinated axons; small receptive fields, infreq distribution

Front 86

warming receptors

Back 86

increase firing when skin is above 32; stop when cool; free nerve endings with unmyelinated axons (c fiber); very small receptive fields

Front 87

Nociceptors

Back 87

respond to stimuli that damage or threaten skin; ~70% of all sensory neurons in DRG; provide almost all innervation to tooth pulp and cornea

Front 88

A-mechanonociceptors

Back 88

axon myelinated (a-delta); respond to intense mech force/extreme heat; free nerve endings; small receptive fields; slowly adapting to detect entire time

Front 89

polymodal nociceptors

Back 89

unmyelinated axon (c fibers); intense mech force, high heat, noxious chemicals; free nerve endings; small receptive fields; slowly adapting; mediate slow, aching, burning quality of pain; difficult to localize

Front 90

dorsal column system

Back 90

sensory pathway for light touch, 2 pt discrimination, vibration, joint position

Front 91

basic pathway for dorsal column system:

Back 91

stimulus-> sensory receptors-> spinal cord-> medulla/brainstem-> thalamus-> cortex

Front 92

spinal cord and dorsal column system

Back 92

-first place in CNS that sensory info goes
-ea level gives rise to 1 spinal n. and 1 DRG on each side
-ea innervates 1 dermatome

Front 93

spinal neurons

Back 93

gray matter on inside of spinal cord containing cell bodies of neurons

Front 94

nucleus/ nuclei

Back 94

clusters of neuronal cell bodies that connect functional systems

Front 95

tracts

Back 95

bundles of projecting axons (fibers) with similar connections/ functions--> course through white matter on outside of spinal cord

Front 96

Major sensory tracts in dorsal columns

Back 96

-fasciculus gracilis
-fasciculus cuneatus

convey tactile, vibration, joint position info to brain

Front 97

major sensory tracts: anterolateral

Back 97

(anterior funiculus)
convey pain, temp info to brain and some crude touch

Front 98

anatomy of spinal cord (horns)

Back 98

dorsal horn: sensory input

ventral horn: contains motor neurons that send efferent info to muscles

Front 99

general regions of spinal cord gray matter are divided into...

Back 99

rexed laminae

Front 100

Laminae I/II

Back 100

gray matter most lateral
receive nociceptive primary afferent input from dorsal roots
(marginal zone and substantia gelatinosa)

Front 101

Laminae III/IV

Back 101

gray matter
receive tactile/vibration afferent input form dorsal roots

Front 102

damage to dorsal column system

Back 102

causes loss in fine touch and vibration sensation below the spinal level of the lesion

Front 103

primary afferent input for dorsal column system

Back 103

all mechanoreceptors afferents that mediate fine touch
(Merkel, Meissner, Pacinian, Ruffini, hair follicle afferents)

Front 104

dorsal column system and spinal cord entry

Back 104

central process of afferents enter medial spinal cord through medial part of dorsal root

Front 105

dorsal column system spinal cord ascent

Back 105

-mostly ipsilateral
-a few local branches synapse in dorsal horn onto spinal nn that send axons across and to anterolateral tract (crude touch)

Front 106

fasciculus gracilis

Back 106

-medial dorsal column
-carries info from T7 and below

Front 107

fasciculus cuneatus

Back 107

-lateral dorsal column
-carries info from T6 and above

Front 108

lumbar region and dorsal columns

Back 108

fasciculus gracilis only

Front 109

thoracic region and dorsal columns

Back 109

segment T7 and below have f. gracilis only
T6 and above have both

Front 110

cervical region and dorsal columns

Back 110

both f. gracilis and cuneatus

Front 111

somatotopy of axons in dorsal columns

Back 111

(med) leg->trunk->arm->neck (lat)

Front 112

cervical and lumbar cord differences in matter

Back 112

cervical: lots of white matter, many axons, distinct dorsal columns

lumbar: lots of gray matter, big ventral horns

Front 113

termination of axons in dorsal column nuclei

Back 113

mechanoreceptor axons ascend and terminate onto 2nd order neurons in Dorsal Column nuclei: nucleus gracilis and nucleus cuneatus

Front 114

dorsal column 2nd order neurons

Back 114

send projections across sensory decussation in caudal medulla, turn and ascend in medial lemniscus

Front 115

dorsal column nuclei

Back 115

-N. Gracilis (medial, leg and trunk), cuneatus (lat, arm and neck)
-(med) leg-->trunk-->arm->neck(lat)
-as column ascends, sensory fibers are added laterally

Front 116

medial lemniscus

Back 116

-bundle of fibers originating in medulla
-made of axons of 2nd order neurons with cell bodies in dorsal column nuclei

Front 117

medial lemniscus ascent

Back 117

caudal medulla --> pons --> midbrain --> thalamus
receptor type info still segregated (merkel with merkel)

Front 118

lesions of medial lemniscus

Back 118

-contralateral deficits in fine touch, 2 pt discrimination, vibration, joint position

Front 119

termination of medial lemniscus

Back 119

2nd order axons asecnding in medial lemniscus terminate in the ventral posterior lateral (VPL) nucleus of the thalamus onto 3rd order thalamic neurons

Front 120

VPL
and somatotopy

Back 120

-receives info about neck and body
-neck is medial, feet are lateral

Front 121

lesions of VPL nucleus in thalamus

Back 121

contralateral deficits in fine discrimination, vibration, joint position

Front 122

3rd order thalamic neurons from dorsal column system

Back 122

from VPL pass laterally through posterior limb of the internal capsule--> fans out as corona radiata rostrally

Front 123

3rd order thalamic neurons form dorsal column system termination

Back 123

terminate in somatosensory cortex (S1) in postcentral gyrus

Front 124

somatorsensory cortex somatotopy

Back 124

medial=legs, lateral=face

Front 125

lesions of S1 cortex

Back 125

contralateral deficits in fine discrimination, vibration, joint position

Front 126

convergence of thalamic neurons

Back 126

receptirve field of one cortical neuron in S1 ma ultimately receive input from 300-400 mechanoreceptors in skin

Front 127

Primary somatosensory cortex (S1)

Back 127

-all sensory info from thalamus goes to S1 cortex first (contains 4 Brodmann's areas 3a, 3b, 1, 2)

Front 128

Brodmann's area 3b

Back 128

-receives input from cutaneous slowly and rapidly adapting receptors
-derives info about details of edges of objects and texture

Front 129

Brodmann's area 1

Back 129

-input from cutaneous rapidly adapting receptors
-dervies info about kinesthesis (limb movement)

Front 130

Brodmann's area 2

Back 130

-input from deep tissue and complex touch from skin
-combines info about finger & limb position with edge info to determine 3D shape

Front 131

Secondary somatosensory cortex (SII)

Back 131

-receives neurons form all 4 SI areas
-project to insular cortex which projects to temporal lobe (imp for tactile memory and recognition)

Front 132

Posterior parietal cortex

Back 132

-where some SI neurons project
-Brodmann's 5&7: integrate tactile info with visual info-->project to motor areas of frontal cortex
-where body is, where stimulus is

Front 133

pain

Back 133

a complex, cognitive perception of sensory stimulus in the context of the environment, previous experiences and emotherions--> product of brain's abstract interpretation of sensory experience

Front 134

analgesia

Back 134

lack of pain

Front 135

anesthesia

Back 135

lack of sensation

Front 136

allodynia

Back 136

pain from a normally non-painful stimulus like light touch

Front 137

paresthesia

Back 137

unpleasant, abnormal sensation; tingling, pricking, tickling

Front 138

acute vs chronic pain

Back 138

acute: critical protective function

chronic: continues after healing or in absence of injury serving no useful purpose

Front 139

nociceptive pain

Back 139

-pain from tissue damage
-activation of nociceptors in skin, inflamm chemicals, nerve receptors
-NSAIDs responsive typically

Front 140

neuropathic pain

Back 140

-direct damage to nerves in the peripheral or central NS
-often burning, lancinating, electrical quality, allodynia common

Front 141

anterolateral system

Back 141

-info about pain and body temp
-made of several pathways of neurons terminating at diff brain levels

Front 142

anterolateral system input

Back 142

-noxious mechanical, thermal or chemical stim
-to free nerve endings of A-delta or C-fiber nociceptors

Front 143

A-delta fibers in anterolateral system

Back 143

-myelinated
-mediate pain first
-immediate, short-lasting, pricking quality

Front 144

C fibers in anterolateral system

Back 144

-unmyelinated
-mediate second pain
- delayed, long lasting, burning quality

Front 145

anterolateral system and spinal cord

Back 145

central processes of nociceptors enter spinal cord dorsal horns (lateral party)--> synapse right away onto 2nd order neurons in Lamina I/II

Front 146

anterorlateral 2nd order neurons

Back 146

-cross to contralateral side within 2-3 segments and ascend in anterolateral quadrant tracts (ventral lateral funiculus)

Front 147

lesion of anterolateral tract

Back 147

contralateral loss of pain and temp complete by 2-3 segments below the lesion

Front 148

anterolateral termination in higher brain centers

Back 148

-3 paths all start in spinal cord but terminate in diff places
-spinothalamic tract, spinoreticular tract, spinomesencephalic trat

Front 149

Spinothalamic tract

Back 149

-majority of 2nd order ascending fibers terminate onto 3rd in thalamus
-mediates discriminative aspects of pain and temp (location and intensity)

Front 150

in thalamus, axons from body terminate in 2 nuclei:

Back 150

VPL and Central lateral nucleus

Front 151

VPL

Back 151

-3rd order axons project to ipsilateral SI cortex
-relay for discriminative somatosensory info from body
-recognizes both dorsal column medial lemniscus and spinothalamic inputs (but segregation of neurons occurs)

Front 152

Central Lateral Nucleus

Back 152

-3rd order neurons project to many areas of cortex, partic limbic cortex (affect, emotion)
-involved in emotional suffering
-CL nucleus is not somatotopically organized

Front 153

thalamus and nociceptive info

Back 153

Processes info--> crude pain and temp sensation is beginning to be appreciated and emotional rxns to pain are initiated

Front 154

thalamus and relaying info

Back 154

relays info to cerebral cortex (SI) by 3rd order neurons that pass through posterior limb of internal capsule and corona radiata to SI cortex

Front 155

similarities of spinothalamic tract and dorsal column system

Back 155

-project to VPL of thalamus
-somatottopically organized
-discriminates and localizes stimuli

Front 156

Spinoreticular tract

Back 156

-2nd order neurons ascend and terminate in medulla and pons--> reticular formation
-mediates changes in level of attention to painful stimuli

Front 157

spinomesencephalic tract

Back 157

-2nd order neurons terminate in midbrain in superior colliculus and in a region of gray matter surrounding cerebral aqueduct called periaqueductal gray (PAG)
-stimulates central modulation of pain
-sends neurons back down to stim. endogenous pain inhibition

Front 158

thalamic neurons of anterolateral tract project to cortex areas:

Back 158

-somatosensory cortex
-cingulate gyrus
-insular cortex

Front 159

thalamic neurons of anterolateral tract to somatosensory cortex

Back 159

SI areas 3b, 2, 1 and SII

localizes stimulus on body

Front 160

thalamic neurons from anterolateral tract in cingulate gyrus

Back 160

-part of limbic system
-processing of emotional component of pain, fear, anxiety, etc

Front 161

thalamic neurons form anterolateral tract in insular cortex

Back 161

processes info on the internal, autonomic state of body (heart races, breathing rapid, etc)
integrates sensory, affective, and cognitive components of pain

Front 162

lesions of insular cortex

Back 162

-asymbolia for pain
-pts can perceive noxious stimuli as painful and localize the pain to body part, but don't display appropriate emotional responses

Front 163

descending pathways that inhibit pain

Back 163

-painful stimuli can be suppressed by endogenous pain control systems
-reticular formation has prominent role

Front 164

descending pathways inhibiting pain neurons

Back 164

-cell bodies in PAG in midbrain--> send axons down to the Raphe nucleus in medulla and to Locus Ceruleus of pons--> send axons down spinal cord where they synapse on inhibitory interneurons or directly on to spinothalamic tract projections to suppress noxious transmission

Front 165

referred pain

Back 165

-area to which the pain is referred corresponds to the dermatome innervated by the spinal segment to which the visceral afferents project
(MI= left chest and arm, T1-T4)

Front 166

Trigeminal nerve

Back 166

-opthalmic (V1), maxillary (V2), mandibular (V3)
-peripheral afferent neurons
-fine touch afferents, nociceptive afferents, thermoreceptors

Front 167

trigeminal ganglion

Back 167

-on each side of head
-cell bodies of sensory neurons innervating head/face
-homologous to DRG for body

Front 168

trigeminal nuclei for fine touch

Back 168

-fibers synapse first in main sensory nucleus in pons

Front 169

trigeminal nuclei for pain and temp

Back 169

-fibers synpase first in spinal trigeminal nucleus (from pons to cervical spinal cord)
-homologous to spinal dorsal horn for body
-caudal nucleus: extends from obex to spinal cord

Front 170

thalamic nuclei for trigeminal system

Back 170

Ventral posterior medial (VPM) nucleus for both fine touch and pain/temp (but they stay segregated)

Front 171

somatotopy of VPM

Back 171

(medial) tongue--> intra-oral cavity--> face (lateral)

Front 172

primary afferent input for trigeminal system

Back 172

mechanoreceptor fibers enter from 3 branches of CN V

Front 173

major primary pathway for trigeminal system

Back 173

fine touch mechanoreceptors synapse in chief sensory nucleus of V in pons on ipsilateral side

Front 174

2nd order neurons for trigeminal system

Back 174

send fibers that cross to other side of the pons and form the trigeminal lemniscus (which joins medial lemniscus)--> ascends to VPM of thalamus--> terminates on 3rd order thalamic neurons

Front 175

minor pathway for crude touch in trigeminal system

Back 175

a few mechanoreceptors enter pons but descend directly in spinal tract of V to spinal nucleus of V where they synpase--> 2nd order neurons cross midline--> ascend in trigeminothalamic tract to VPM

Front 176

minor pathway for oral cavity in trigeminal system

Back 176

-dorsal trigeminal tract
-a few mechanoreceptors enter the pons and synapse in cheif sensory nucleus--> 2nd order neurons don't cross-->ascend on ipsilateral side to VPM

Front 177

3rd order VPM thalamic neurons in trigeminal system

Back 177

send projections through posterior limb of the internal capsule and corona radiata and terminate in the lateral aspect of the SI cortex (near lateral fissure)

Front 178

primary afferent input for trigeminal pain and temp

Back 178

nociceptors form the face enter CN V at pons, immediately descend in spinal trigeminal tract without synapsing, terminate in spinal trigeminal nucleus of V

Front 179

2nd order neurons for pain/temp in trigeminal system

Back 179

send axons that corss to other side of medulla and ascend as the trigeminothalamic tract to VPM of thalamus

Front 180

3rd order neurons for pain/temp in trigeminal system

Back 180

neurons in VPM project through the posterior limb of internal capsule and corona radiata up to lateral SI cortex (some others to reticular formation)

Front 181

trigeminal neuralgia

Back 181

-lancincating, severe pain that last seconds to minutes
-region of V2/3
-treat with carbamazepine (anticonvulsant works on Na+ channels)

Front 182

Temperomandiulbar joint disorder

Back 182

-chronic pain localized at TMJ or in muscles of mastication
-recurrent headaches, toothaches

Front 183

lesions of thalamus and cortex

Back 183

contralateral deficits in all sensation

Front 184

lesion on one entire side of cord

Back 184

-ipsi loss of fine discrim, joint position, vibration below lesion
-contra loss of pain and temp 2-3 segments below lesion
-some contra loss of crude touch

Front 185

alternating sensory loss in body (fine discrim on one side, pain and temp on the opposite side)

Back 185

usually idicates a unilateral lesion in the spinal cord

Front 186

lesions in brainstem (above caudual medulla) or higher

Back 186

contra loss of tactile and pain/temp in body

Front 187

dorsal lesion above caudal medulla

Back 187

contra loss of tactile and pain/temp

Front 188

Lesion of VPL or VPM in thalamus

Back 188

loss is contralateral

Front 189

lesion at cortex

Back 189

loss is contralateral

Front 190

rhizomy (cutting of dorsal roots)

Back 190

-lose fine discrim, joint position, vibration, pain/temp in dermatome innerv by cut dorsal roots
-surgeons typically cut dorsal roots adjacent to affected dermatomes

Front 191

cordotomy (surgical cutting of anterolateral fiber tracts in spinal cord)

Back 191

-cut 2-3 segments rostrally
-one side: lose pain and temp on contra side
-both sides: lose pain/temp both
-only for terminally ill

Front 192

Peripheral nerve lesion causes

Back 192

trauma, diabetes, neuropathy

Front 193

peripheral nerve lesion deficit

Back 193

lack of fine discrimination, pain/temp in skin, only in parts of limbs (glove and stocking)

affects multiple dermatomes

Front 194

complete cord transection causes

Back 194

trauma, fx or dislocated vert causing cord compression, penetrating injuries, tumors, MS

Front 195

complete cord transection deficit

Back 195

bilateral loss of all sensation below lesion and loss of motor control

Front 196

anterior cord syndrome causes

Back 196

fx vert--> contusion of spinal cord

infarct form anterior spinal artery embolism (blood clot)

Front 197

anterior cord syndrome deficit

Back 197

-bilateral loss of pain and temp below lesion
-spares dorsal columns- fine touch OK
-can get weakness from effect on motor neurons

Front 198

posterior cord syndrome causes

Back 198

trauma, extrinsic compression from tumors, syphalis (tabes dorsalis)

Front 199

posterior cord syndrome deficit

Back 199

loss of fine touch below level of lesion

pain and temp OK

Front 200

central cord syndrome causes

Back 200

-syringomyelia (tube-like enlargement of central canal)
-gliosis or cysts in central part of cord
-hyperextension of cervical spine (usually lower cervical or upper thoracic)

Front 201

central cord syndrome: small lesion deficit

Back 201

-cuts anterolateral fibers that cross in ant commissure
-bilateral loss of pain and temp in affected dermatomes: cape-like
-dorsal columns usually spared

Front 202

central cord syndrome: large lesion deficit

Back 202

-bilateral loss of pain/temp
-bilateral loss of fine touch below lesion
-motor neuron loss
-may spare sacral part of anterolateral tracts

Front 203

Brown-Sequard syndrome (hemisection of cord) causes

Back 203

penetrating injuries, tumor compressing ascending pathways, MS, herniated disk
(usually incomplete)

Front 204

Brown-Sequard deficit

Back 204

-ipsi loss of fine touch below lesion
-contra loss of pain and temp by 2-3 segments below lesion

Front 205

unilateral lesion in VPL or VPM or SI cortex causes

Back 205

stroke, hemorrhage, brain tumor, MS, trauma affecting one side of thalamus

Front 206

unilateral lesion in VPL deficit

Back 206

contralateral loss of fine touch and pain/temp in body

sensation in face is intact bc VPM is intact

Front 207

unilateral lesion in VPM deficit

Back 207

contralateral loss of fine touch and pain/temp in face and head

Front 208

unilateral lesion in SI cortex deficit

Back 208

contra loss of fine touch and pain/temp in body and/or face
(feet fibers most medial, head most lateral)

Front 209

brain stem lesion in lateral medulla deficit

Back 209

-contra loss of pain/temp in body
-contra loss of pain/temp in face
-ipsi loss of pain/temp in face

medial lemniscus ok=body fine touch OK

Front 210

light path

Back 210

cornea-anterior chamber-lens-vitreous-retina

Front 211

function of the cornea

Back 211

-protective function
-eye's outermost lens (65-75% of eyes total focusing power)

Front 212

nourishment for the cornea

Back 212

-no blood vessels
-tear and aqueous humor filling chamber behind it

Front 213

5 tissue layers of the corneum

Back 213

1. epithelium
2. Bowman's membrane
3. stroma
4. Descemet's membrane
5. endothelium

Front 214

corneal epithelium

Back 214

-blocks passage of foreign material
-smooth surface to absorb oxygen and nutrients
-lots of nerve endings=sensitive
-highly regenerative stratified squamous

Front 215

corneal Bowman's membrane

Back 215

-collagen
-if injured, can scar

Front 216

corneal stroma

Back 216

-90% of cornea's thickness
-water and collagen
-gives strength, elasticity, form
-necessary for light-conducting

Front 217

corneal Desccemet's membrane

Back 217

-protective barrier against infection and injury
-collagen and endothelial cells
-regenerated

Front 218

corneal endothelium

Back 218

-very thin
-pumps XS fluid out of stroma

Front 219

Refractive errors

Back 219

myopia: nearsighted, eye too long
hyperopia: far sighted, eye too short

Front 220

uvea: 3 parts

Back 220

-choroid
-ciliary body
-iris

Front 221

choroid

Back 221

-vessel layer (a&v, loose CT, melanocytes)
-chorocapillary layer (fenestrated capillaries in one plane)
-Bruch's membrane (amorphous hyaline membrane)

Front 222

ciliary body

Back 222

-expansion of stroma of choroid near the lens
-vitreous body, sclera, post. chamber
-ciliary processes project to lens

Front 223

iris

Back 223

-covers lens
-regulates amt of light reaching retina

Front 224

anterior aspect of iris

Back 224

-vascular, loose CT with interspersed melanocytes
-number and type of melanocytes determines eye color

Front 225

posterior surface of iris

Back 225

-double layer of pigmented epith to absorb light
-2 muscle masses rest on it and regulate iris opening (pupil diameter)

Front 226

dilator pupillae m.

Back 226

-radially arranged myoepithelial cells
-btw vascular and pigmented layers of iris
-symp innervation

Front 227

sphincter pupillae muscle

Back 227

-concentric smooth muscle bundles at pupil margin
-parasymp innerv

Front 228

Anterior chamber

Back 228

-contains aqueous humor
-avascular
-maintains intraocular pressure
-btw cornea and iris/lens

Front 229

aqueous humor circulation

Back 229

-produced by ciliary processes in post chamber--> anterior chamber--> trabecular meshwork--> canal of Schlemm-->venous system
-no direct cxn btw trebec and canal: humor percolates through tissue into canal

Front 230

Open angle (chronic) glaucoma

Back 230

-80-85% cases
-obstruction in drainage of eye
-passes too slowly through meshwork drain
-pressure builds and can damage optic nerve

Front 231

angle-closure glaucoma

Back 231

-blindness in 24-48 hours
-angle btw iris and cornea narrows, blocking draining of aq humor

Front 232

clinical signs of glaucoma

Back 232

-increased pressure
-increased cupping of optic nerve head (inc cup:disc)
-visual field defect will reveal a selective peripheral loss of sensitivity

Front 233

lamina cribosa

Back 233

network of collagen through which fibers of optic nerve exit--> may be altered in glaucoma

Front 234

lens

Back 234

-very transparent: avascular, little ECM
-2nd to corneal refractive power
-supported by system of fibers (suspensory ligaments or zonules) attached to ciliary body

Front 235

Lens structure

Back 235

-capsule: ECM surrounding lens
-epithelium: ant. surface
-lens fibers: body of lens, no organelles

Front 236

accommodation

Back 236

-lens thinner when focused on distant objects, relaxed ciliary muscles
-dynamically changes focus of eye

Front 237

vitreous body

Back 237

-nearly acellular
-maj macromolecules: type 2 collagen, hyaluronic acid
-nutritive function

Front 238

cataracts

Back 238

-occur as lens ages
-nuclear, cortical or posterior capsular
-replace lens to accommodate again

Front 239

retina regions

Back 239

-neural or sensory retina
-retinal pigment epithelium

Front 240

retinal layers

Back 240

-Bruch's
-RPE
-outer segments
-inner segments
-outer limiting membrane
-outer nuclear layer
-fiber layer
-inner nuclear layer
-inner synaptic layer
-ganglion cell layer
-optic fiber layer
-inner limiting membrane

Front 241

fovea

Back 241

-small pit
-region lateral to optic nerve
-used for high acuity vision

Front 242

anterior retina

Back 242

-number of neural elements declines
-becomes a single layer of unpigmented epithelium covering ciliary body

Front 243

layer of photoreceptor outer and inner segments

Back 243

-most posterior (last thing for light to reach)
-rods and cones

Front 244

outer nuclear layer

Back 244

nuclei of rods and cones

Front 245

outer plexiform layer

Back 245

location of synapses of rod and cone axons with next layer of neurons (bipolar)

Front 246

inner nuclear layer

Back 246

nuclei of bipolar neurons (also nuclei of horizontal and amacrine neurons and Muller glia)

Front 247

inner plexiform layer

Back 247

synapss of bipolar axons with ganglion cells

Front 248

ganglion cell layer

Back 248

ganglion cell nuclei

Front 249

nerve fiber layer

Back 249

axons of ganglion cells that converge to form optic nerve

Front 250

inner limiting lamina

Back 250

basement membrane fo Muller glial cells

Front 251

Photoreceptor segments

Back 251

-Inner: organelles for protein synthesis and energy production
-Outer: flattened membrane discs with photosensitive visual pigments (where proteins go via cilum)

Front 252

rods

Back 252

-long, slender outer segments
-numerous except at fovea
-very light sensitive

Front 253

cones

Back 253

-conical outer segments with membrane discs
-responsible for high acuity and color vision
-only photoreceptor in fovea

Front 254

foveal development

Back 254

-multiple anatomical events
-core packing increases postnatally from an initially uniform dist.
-foveal pit develops after a thickening of retina
-site of incipient fovea is avascular all along

Front 255

RPE

Back 255

-simple, cuboidal, MELANIN-containing epithelium btw neural retina and Bruch's membrane
-provides outer blood-retinal barrier

Front 256

RPE functions

Back 256

-absorbs scattered light
-transports nutrients and ions
-spatial buffering
-re-isomerization of all-trans retinal
-outer segment renewal
-secretes GFs for maintenance

Front 257

retinal blood supply

Back 257

-outer: choriocapillaries
-inner: central retinal artery from opthalmic artery

Front 258

without foveal specialization...

Back 258

-albinism because normally increased melanin contributes to avascularization (for high acuity vision)

Front 259

in each eye, you have:

Back 259

-100 million rods for vision in very low light
-5 million cones for day-time vision

Front 260

cones and cone system

Back 260

-photopic
-less sensitive, fast
-don't saturate
-high spatial resolution
-less pigment

Front 261

rod and rod system

Back 261

-scotopic
-more sensitive, slow
-saturate
-poor spatial resolution
-more pigment

Front 262

photoreceptors response to light

Back 262

hyperpolarization

Front 263

univariance

Back 263

-photoreceptors cannot register the wavelenth of photons they catch
-depends on number of photons

Front 264

Visual pigment g-coupled protein cascade

Back 264

-light activates photopigments-->stim G-protein (transducin) amplification--> activates cGMP phosphodiesterase--> breakdown of cGMP-->channels close-->decrease Na+-->hyperpolarization

Front 265

countering effects of light

Back 265

-decrease in ca2+ depresses PDE activity and enhances guanylate cyclase activity
-increases cGMP in OS
-counters light effects

Front 266

retinitis pigmentosa

Back 266

-defect affecting rods
-rhodopsin, PDE, GMP gated ion channels, arrestin

Front 267

congenital stationary night blindness

Back 267

-affects rods
-rhodopsin, transducin, PDE, rhodopsin kinase

Front 268

cone, cone-rod, and macular degeneration

Back 268

-affects cones
-GCAP1, guanylate cyclase, ABCR

Front 269

rod monochromacy

Back 269

-affects cones
-GMP gated ion channel, cone transducin

Front 270

red/green vision defects and blue-cone monochromacy

Back 270

-affects cones
-cone-opsin

Front 271

Receptive field concept

Back 271

-every neuron (that is higher order than photoreceptors) has a receptive field
-retinal area (of photoreceptors) that when stimulated influences the activity of that neuron

Front 272

Hyperpolarization=universal response of photoreceptors to light

Back 272

-as they hyperpol, release less NT
-light turns them OFF--> "off cells"
-hyper and depolarize in a graded fashion, release NT in graded fashion

Front 273

when a cone is depolarized...

Back 273

-releases excitatory NT glutamate
-occurs when light is NOT present

Front 274

parallel pathways

Back 274

-even though the cones all act in the same way in response to light, activity of a single cone gives rise to two parallel pathways

Front 275

On center Bipolar cells

Back 275

-"on center" cells-- light in center turns them on (metabotropic)
-invaginating contacts onto cone
-sign reversing of cone output (which is off-center)
-light depolarizes them (glutamate from photoreceptors would hyperpol-- inhibitory action)

Front 276

Off center bipolar cells

Back 276

-ionotropic receptors
-flat contacts on to cones
-classical excitatory synapses (sign CONSERVING)
-light-->hyperpolarizes

Front 277

why does cone system have 2 parallel channels but rod system only has one?

Back 277

-organization allows one channel to provide info to the ganglion cell concerning brighter than background stimuli (ON center channel) and the other, darker than background stimuli (the OFF center channel)

Front 278

bipolar cells talk to:

Back 278

-amacrine cells (lateral cxns; transient depolarizing responses)
-ganglion cells (produce APs)

Front 279

physiological types of ganglion cells

Back 279

-on center or off center
-either can have either sustained or transient responses
-melanopsin ones are photosensitive

Front 280

parasol ganglion cells

Back 280

-exhibit M cell behavior
-large cells with large receptive fields --> more transient responses
-project to M (magnocellular layers of LGN)

Front 281

midget ganglion cells

Back 281

-exhibit P cell behavior
-smaller cells with small receptive fields have more sustained responses
-project to P (parvocellular layers of LGN)

Front 282

Horizontal cells

Back 282

-elaborate system of inhibitory interneurons that synaptically interconnects photoreceptors
-ie every cone has a reciprocal synaptic relationship with all of its neighboring cones

Front 283

rod monochromacy

Back 283

-absence of cone-based vision in the eye
-intense glare in bright conditions
-poor acuity, poor fixation, nystagmus, visual field defects, etc

Front 284

rod monochromacy causes

Back 284

-mutations in CNG channel subunits or GNAT2 (cone transducin)
-cones are unable to hyperpolarize in response to light

Front 285

red-green dichromacy

Back 285

-missing the function of the one of the three cone types
-protanopia and dueteranopia are x-linked

Front 286

congenital color vision defects

Back 286

-present at birth
-constant type and severity
-both eyes equally affected
-visual acuity unaffected

Front 287

acquired color vision defects

Back 287

-onset after birth
-flucuating type/severity
-monocular differences
-reduced visual acuity
-predom. tritanopia
-equal male/female incidence

Front 288

Retinitis Pigmentosa

Back 288

-rhodopsin mutations alter ROD function via disrupting transport to OS
-difficulty seeing in dim light
-gradual loss of peripheral vision
-rods secrete cone-surviving factor so eventually lose cones
-inherited

Front 289

Usher's syndrome

Back 289

most common form of deaf-blindness

defect in transport proteins (ciliary defect)

Front 290

geniculo-striate system

Back 290

-conscious visual perception
-retina--> LGN-->striate cortex-->extrastriate cortex

Front 291

retino-tectal system

Back 291

-directing eye movements and visual attention
-retina --> superior colliculus --> pulvinar --> extrastriate cortex

Front 292

pupillary constriction

Back 292

-pregeniculate body--> pretectum-->EW nucleus--> ciliary ganglion-->pupillae constric mm
-consensual light reflex (both eyes) d/t linking via post. commissure

Front 293

pupillary dilation

Back 293

-pregenic body--> projection to midbrain retic formation--> descends to thoracic cord--> symp chain--> superior cerv gang--> pupillae dilator mm.
-symp: emotion can cause dilation

Front 294

accommodation pathway

Back 294

retina-->LGN-->visual cortex --> pretectum --> crossover --> EW nucleus--> ciliary gang --> contraction to plump up lens to see close objects

Front 295

contraction of ciliary m

Back 295

thickening of lens

(flattening of lens is passive)

Front 296

When attention is directed to nearby objects...

Back 296

-convergence of the 2 eyes
-contraction of ciliary m to thicken lens
-pupillary constriction to increase depth of field

Front 297

how accommodation differs form pupillary reflex

Back 297

-accomm can be voluntarily controlled
-reg by neg feedback mech that automatically adjusts focal power of lens
-pathway includes cerebral cortex

Front 298

Retinal topography= visual field topography

Back 298

-cornea and lens of the eye create an image of the visual field on the retina

Front 299

retinotopy

Back 299

-fibers in adjacent gang cells in each hemiretina stay together
-fibers from each nasal hemiretina cross
-preserved in LGN
-up is down, L is R

Front 300

Cortical over-representation of the fovea

Back 300

-fovea contains more gang cells than periphery--> more fibers and cells--> more cortical area (magnif)
-acuity at center of gaze is much better than periphery

Front 301

fMRI responses

Back 301

-used to identify brain sites that respond best to stimulation at different visual field eccentricities

Front 302

hemianopia and quadrantanopia

Back 302

-loss of vision in a hemifield or quadrant

Front 303

homonyous

Back 303

corresponding loss of vision in each eye

Front 304

heteronomous

Back 304

non-corresponding loss in each eye

Front 305

functional specialization of visual cortex

Back 305

-many intervening stages--> hierarchy of visual areas
-multiple pathways--> parallel processing

Front 306

Symptoms of trauma to extrastriate cortex....

Back 306

-lesions at higher levels will become more functionally specific
-lesions can result in selective loss of function (agnosias) rather than blindness

Front 307

Extrastriate visual area organization

Back 307

-what is it--> temporal lobe pathways for recognition of objects
-where is it--> parietal lobe for localization esp directing visual attention to an object of interest

Front 308

lesions up to and including V1

Back 308

-produce blindness
-all different functional pathways are cut

Front 309

lesions of hMT+

Back 309

-selective loss of motion perception
(sees someone enter room, then they're on the other side and don't know how they got there)

Front 310

lesion of V4/V8

Back 310

-cerebral achromatopsia (loss of color vision due to brain injury)

Front 311

lesion of FFA

Back 311

-Prosopagnosia = inability to recognize familiar faces
-often accompanies cerebral achromatopsia

Front 312

lesions of PVA (primarily on right)

Back 312

-attentional neglect

Front 313

outer ear

Back 313

pinna and external auditory meatus (canal)

Front 314

middle ear

Back 314

-begins at tympanic membrane
-tympanic cavity, ossicular chain and Eustacian tube

Front 315

inner ear

Back 315

-begins at oval window
-includes cochlea and vestibular structures

Front 316

ear canal (external auditory meatus)

Back 316

-concha to eardrum
-outer third is cartilaginous
-inner 2/3 is bony
-provide boost in high freq sound intensity

Front 317

Middle ear bones

Back 317

tympanic membrane--> handle of malleus--> vibrates --> incus --> stapes -->footplate on oval window

Front 318

Ossicles of middle ear amplify sound vibration by

Back 318

-a lever mechanism (2dB of gain)
-the area different between the tympanic membrane and the footplate of the stapes (23 dB)
-buckling of tympanic membrane

Front 319

protective feedback to dampen vibration of ossicles

Back 319

-tensor tympani attached to handle of the malleus
-stapedius muscle attached to neck of stapes

Front 320

Where is inner ear contained

Back 320

-petrous apex of the temporal bone
-encased in a bony labyrinth

Front 321

sections of the bony labyrinth

Back 321

-vestibule, cochlea, semicircual canal

Front 322

Modiolus

Back 322

-core of the cochlea
-highly porous bone that allows passage of auditory nerve fibers from internal aud meatus to hair cell synapse

Front 323

osseous spiral lamina

Back 323

-coils around center of cochlea
-partial division of upper and lower cochlear chambers into scala vestibuli and tympani
-pt of attach for basilar membrane

Front 324

cochlear chambers all connect at the

Back 324

helicotrema

Front 325

scala media

Back 325

-membranous labyrinth of the cochlea following the shape of the osseous cochlea
-sup. border: Reissner's membrane
-inf. border: basilar membrane

Front 326

Sensory organ of hearing in membranous labyrinth

Back 326

-organ of Corti

Front 327

Along lateral wall of membranous labyrinth..

Back 327

-stria vascularis: highly vascular tissue that is responsible for the metabolic environment of the scala media

Front 328

organ of Corti

Back 328

-longitudinally along length of basilar membrane
-one row inner hair cells
-3 rows outer hair cells
-cell bodies surrounded by supporting cells

Front 329

Perilymph

Back 329

-high Na+, low K+
-in scala vestibule and tympani

Front 330

Endolymph

Back 330

-high K+, low Na+
-in scala media

Front 331

stria vascularis

Back 331

-maintains ionic concentrations of endolymph

Front 332

communication between endolymphatic sac and membranous labyrinth

Back 332

-via endolymphatic duct and vestibular aqueduct

Front 333

innervation of hair cells

Back 333

-contacted by dendrites of afferent bipolar neurons whose cell bodies are in the spiral ganglion
-90-95% contact inner hair cells

Front 334

afferent fibers and hair cells

Back 334

-many afferent fibers synapse on the same inner hair cell
-single afferent fibers branch to synapse with several outer hair cells

Front 335

Efferent fibers and hair cells

Back 335

-cell bodies in the superior olivary complex of brainstem
-synapse directly on outer hair cells and on afferent fibers of inner hair cells

Front 336

tonotropic organization of cochlea

Back 336

-high freq stim.= near narrower base (stiff, near stapes)
-low freq stim= near wider apical side of basilar membrane

Front 337

outer hair cells as amplifiers

Back 337

-change length to amplify motion of the basilar membrane-->generate vibrations that travel backwards--> vibrate tympanic membrane--> generate otoacoustic emissions
-contain mt's for motile props
-12,000 total (strial side)

Front 338

inner hair cells as sensory receptors

Back 338

-main transducer
-20 afferent fibers and 20 independent synapses per
-3500 total (modiolar side)

Front 339

cuticular plate

Back 339

-apical portion of all hair cells
-thickened region
-in conjunction with supporting cells forms the reticular lamina

Front 340

stereocilia

Back 340

-stiff, hair-like structures that deflect with mech disturbances
-rooed in the cuticular plate of each hair cell
-connected to each other by filamentous cross-links and tip-links

Front 341

traveling wave

Back 341

-produced as pressure waves are transmitted from middle ear to the cochlea--> cochlear fluid is displaced--> wave like motion along basilar membrane

Front 342

hair cell function and synaptic stimulation

Back 342

-movement of endolymph produces deflection of stereocilia --> opens ion channels of stereocilia --> +ions flow in --> depolar --> NT release stimulation auditory nerve fibers

Front 343

conductive hearing loss

Back 343

occlusion or dysfunction of the external and/or middle ear

Front 344

sensorineural hearing loss

Back 344

dysfunction of the cochlea and/or auditory nerve

Front 345

function of vestibular apparatus

Back 345

-maintain upright posture
-adjust head position in response to changes in posture
-coordinate eye movements with each other and to compensate for head movement

Front 346

bony labyrinth

Back 346

-space in temporal bone
-lined with membrane
-gap filled with perilymph

Front 347

membranous labyrinth

Back 347

-filled with endolymph
-divided into cochlear and vestibular labyrinths

Front 348

Maculae

Back 348

-in utricle and saccule (vestibular)
-detect linear acceleration

Front 349

otolithic membrane

Back 349

-cover hair cells in macula epith
-made of Ca2+ carbonate crystals (make it denser than endolymph)

Front 350

maculae sensory pathway

Back 350

-movement of membranous lab-->endolymph movement lags in vestibule-->inertia --> stereocilia deflection toward kinocilium leads to hair cell deplarization--> tip links open membrane channels --> depolarization

Front 351

macula orientation

Back 351

-utricle: horizontal (forward-backward, side-side)
-saccule: vertible (forward-backward, up-down)

Front 352

crista ampullaris

Back 352

-in each semicircular canal
-detects angular movement
-sensory epith covered by gelatinous material = the cupola

Front 353

crista ampullaris pathway

Back 353

rotation of head--> rotation of bony lab --> movement of endolymph in membranous lab --> inertia makes endolymph lag and be in opp direction --> deflect cupola --> deflect stereocilia toward kinocilia --> hair cells depolarize and inc NT release --> synpase with aff and eff fibers nasally

Front 354

functional pairs of semicircular canals

Back 354

-R horiz/ L horiz
-R sup/ L post
-R post/ L sup

Front 355

CN VIII (vestibulocochlear)

Back 355

-bipolar cells
-nuclei in vestibular (scarpa's) gang --> lateral end of internal acoustic meatus
-central processes synapse onto vestibular nuclei --> low pons and medulla

Front 356

vestibular nuclei

Back 356

-caudal pons (superior and lateral)
-rostral medulaa (medial and inferior)

Front 357

lateral vestibulospinal tract function

Back 357

-maintains balance and posture
-input to vestibular nuclei via CN VIII

Front 358

LVST route

Back 358

-descends ipsilaterally from lateral vestibular nucleus to all spinal cord levels

Front 359

LVST mech

Back 359

-excites extensor muscles of neck, back and lower limbs (antigravity muscles)
-inhibits flexor muscles
-modified by info from inner ear and cerebellum

Front 360

MVST function

Back 360

-adjust head position in response to postureal changes
-coordinates eye movements with ea other
-coordinates eye movements to compensate for head movements

Front 361

MVST pathway to adjust head position

Back 361

-descends bilaterally from medial vestibular nucleus to cervical spinal cord levels

Front 362

MVST pathway to coordinate eye movement with each other

Back 362

-projects superiorly and bilaterally along medial longitudinal fasciculus (MLF) from vestibular nuclei to paramedian pontine reticular formation (PPRF)--> projects to the ipsilateral abducens nucleus --> contralateral oculomotor nucleus

Front 363

central pathways for vestibulocular reflex (VOR)

Back 363

-semicirc canals detect head movement toward L--> send signal to vestibular nuclei--> project to brainstem nuclei controlling extraoc. muscles--> contract--> move eyes to R to maintain foveation

Front 364

nyastagmus

Back 364

-rhythmic oscillations of the eyeballs
-from rotation of head, observing a moving object, temp-generated convection currents

Front 365

train moving from R-->L, experience...

Back 365

R nyastagmus

Front 366

movement of warm water in L ear canal...

Back 366

L-beating nystagmus

(COWS)

Front 367

movement of cold water in L ear canal...

Back 367

R-beating nystagmus

(COWS)

Front 368

where do auditory nerve fibers synapse

Back 368

in cochlear nucleus

Front 369

recognition of sound pathway

Back 369

-dorsal and ventral cochlear nuclei--> contralateral inf colliculus via lateral lemniscus

Front 370

localization of sound pathway

Back 370

ventral cochlear nucleus--> superior olivary complex in pons --> binaural convergence --> projects to inf colliculus

Front 371

Inferior colliculus role is auditory pathways

Back 371

-relays both recognition and localization pathways
-to medial geniculate nucleus of thalamus
-MGN fibers terminate in 1* aud cortex in superior temporal lobe

Front 372

Wernicke's area

Back 372

-speech interpretation
-cuases expansion of L cortex

Front 373

topography in auditory system

Back 373

-limited use
-multiple decussations and commissures so info from each ear ascends on both sides of brain

Front 374

topography of auditory receptor array

Back 374

-thin end of basilar membrane (basal) = high freq
-thick end (apical) = low freq
-thus, tono-topic

Front 375

receptive field of an auditory nerve

Back 375

-region os basilar membrane to which it is responsive
-best freq= characteristic freq

Front 376

freq tuning curve

Back 376

-describes how well a cell responds to higher and lower freq's
-increasing sound intensity makes tuning curve broaden

Front 377

preservation of freq sensitivity

Back 377

-preserved in relative positions of fibers and cells within each pathway
-maps are found in most maj auditory nuclei (ie inf colliculus, 1* and 2* auditory cortex)

Front 378

Cortex around A1

Back 378

-responsible for higher order processing of sound
-Wernicke's for speech analysis
-Broca's for speech production

Front 379

lesions of auditory cortex

Back 379

-affect perception of complex sounds like speech
-ie wernicke's aphasia (doesn't produce speech bc doesn't understand)

Front 380

unique quality of cells in auditory cortex

Back 380

-can be selectively responsive to complex features of sounds
-ie audiogram showing speech sounds are composed of an initial formant that changes over time, followed by a sustained tone

Front 381

higher order cortical areas for auditory

Back 381

-can contain cells that are selectively responsive to combos of tones

Front 382

how do ears locate a sound

Back 382

-use binaural time and intensity differences in the two ears

Front 383

Superior olivary complex and auditory system

Back 383

-contains cellular structures uniquely designed to detect auditory time and intensity differences

Front 384

temporal coincidence

Back 384

-circuitry in superior olivary complex that can create a neural code for location in space
-neurons need simultaneous input from each ear to fire

Front 385

vertigo

Back 385

illusory sense of environmental or personal rotation
(vestibular)

Front 386

dysequilibrium

Back 386

inability to maintain a normal gait and upright posture
(cerebellum, proprioception, vestibulospinal, motor)

Front 387

diplopia

Back 387

-usually binocular, can be mono
(CN disorders, retinal detachment)

Front 388

syncope

Back 388

loss of consciousness with loss of postural tone
(CV, pulmonary, hematologic, neurologic)

Front 389

vestibular system

Back 389

-semicircular canals, utricle, saccule
-endolymph is circulated by inertia to maintain equil during head motion

Front 390

cochlear system

Back 390

-sound is converted to vibration and transmitted through cochlear duct

Front 391

activation of the unilateral horizontal canal

Back 391

eyes deviate contralaterally

Front 392

activation of the anterior canals

Back 392

eyes deviate up

Front 393

activation of the posterior canals

Back 393

eyes deviate down

Front 394

Deviation of eyes to L...

Back 394

R system activates and L system deactivates to push you out of equil.

applies only during VOR

Front 395

Head turn to the left:

Back 395

-activates L vestibular system
-inhibits R vestib system
-allows eye deviation to R

Front 396

nystagmus in vestibular disorders

Back 396

-slow phase beats towards hypoactive vestibular system
-fast pahse towards hyperactive side

Front 397

fast phase of nystagmus

Back 397

-mediated by the cortex
-rapidly corrects slow deviation and tries to maintain straightforward gaze

Front 398

-5 brief episodes of dizziness, no hearing loss
-once acute hearing loss, vertigo, imbalance
-slow phase nystagmus to R

Back 398

-ischemic stroke in R vesitbular system
-in labyrinthine artery (accompanies CN VII, VIII into internal acoustic meatus)

Front 399

-acute vertigo when getting out of bed for 15-30s
-episodes triggered by turning over on R side in bed
-slow phase to L
-recently had dental work-- head tilted way back

Back 399

-BPPV on R side

Front 400

benign paroxysmal positional vertigo (BPPV)

Back 400

-otoconia detach from wall of utricle and fall into a SCC
-activate the system on that side by creating currents in the endolymph

Front 401

Dix-Hallpike maneuver

Back 401

-for diagnosing BPPV
-turn head toward side you think is affected--> push person down as fast as you can--> fast phase toward ground, slow phase away from ground

Front 402

Epley maneuver

Back 402

-treating BPPV
-pt's head slowly rotated through sequential positions, flushing ocotonia thorugh SCC, stay upright after for 24-48 hrs
-get otoonia into utricle where they can reanneal

Front 403

sound vibrations and window flexing

Back 403

-round window flexes outward at scala tympani, thereby allowing oval window to flex inward into scala vestibule and vice versa

Front 404

-nystagmus with fast to R
-recurrent vertigo when straining, loud music, pushing R ear

Back 404

-R peri-lymphatic fistula (activating)

Front 405

perilymphatic fistula

Back 405

-activating
-allows leakage of endolymph --> current activates vesitbular system

Front 406

-abrupt episodes of vertigo, nausea, vomiting
-slow phase to L
-also thrown to floor
-now has diminished hearing on R

Back 406

-R Meniere's disease (activating)

Front 407

Meniere's Disease

Back 407

-abnormal accumulation of endolymph
-mixes with perilymph from cochlear system, activates vestib system
-triggered by barometric pressure and high salt intake

Front 408

Tumarkin's otolithic crisis

Back 408

-sudden falls, being thrown to the floor
-d/t interruption of vestibulospinal tract activity --> lose equilibrium

Front 409

Pike's peak audiogram

Back 409

-lose low freq hearing, then high freq hearing, middle freq intact
-seen in Meniere's over time

Front 410

-persistent severe vertigo
-cough, rhinorrhea, fever
-slow phase to L
-generalized imbalance

Back 410

-L vestibular neuritis (inhibiting)

Front 411

vestibular neuritis

Back 411

-2nd most common cause of vertigo
-inflamm of vestib. nerve (not gang)
-slow phase towards abnormal side
-hearing preserved
-symptoms for 48 hrs to 6 weeks

Front 412

-2 mo in hospital for periotonitis
-severe balance problem
-no vertigo or hearing loss
-can't read signs while driving
-no nystagmus

Back 412

-Aminoglycoside induced ototoxicity
-treatment for peritonitis killed hair cells so fluid moves but nothing is activated

Front 413

-severe vertigo and spatial disorientation
- decreased hearing on R
-hyperventilation --> fast phase to L with severe vertigo, nausea, vomiting

Back 413

-cerebello-pontine angle tumor on R (inhibiting)

Front 414

Cerebello-pontine angle tumor

Back 414

-vestibular schwannoma
-meningioma

Front 415

Cerebello-pontine angle tumor and hyperventilation

Back 415

-reduces CO2, altering endolymph production
-compromised vestibular system cannot fully compensate for because of tumor

Front 416

-car sickness as child
-vertigo often followed by unilateral pulsatile headache
-more freq around menses
-dix-hallpike: severe downbeat nystagmus

Back 416

-migraine manifesting as dizziness

Front 417

-paroxysmal episodes of severe vertigo
-confusion
-vertigo assoc with perception of environmental tilt

Back 417

-seizure
-"tornade epilepsy"
-abnormal cortex firing gives perception of vertigo