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Neuroscience > SM02 Mini3 > Flashcards

SM02 Mini3 Flashcards

1
Q

how many lobes of the brain are there?

A

5

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2
Q

what are the lobes of the brain?

A

temporal

parietal

occipital

frontal

insula

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3
Q

Broadmann’s area for primary visual cortex

A

17

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4
Q

Broadmann’s area for primary auditory cortex

A

41, 42

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5
Q

Broadmann’s area for primary motor cortex

A

4

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6
Q

Broadmann’s area for primary somatosensory cortex

A

3, 1, 2

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7
Q

bulges or ridges of folds in brain

A

gyri

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8
Q

valleys or grooves of folds in brain

A

sulci

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9
Q

what is the purpose of folding of the brain?

A

increase surfaces area

allows nutrient access

thus increasing # of neurons

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10
Q

central sulcus

A

separates frontal & parietal lobes

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11
Q

lateral sulcus

A

aka sylvian fissure

separates temporal lobe from frontal & parietal lobes

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12
Q

where is the insula found?

A

deep to the lateral sulcus

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13
Q

parts of the insula

A

anerior insula cortex

posterior insular cortex

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14
Q

function of the anterior insular cortex

A

believed to be involved in olfactory, viscero-autonomic, gustatory (taste) & limbic (emotional) functions

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15
Q

function of the posterior insular cortex

A

believed to be involved in auditory, somatosensory & skeletomotor fucntions

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16
Q

how many Broadmann’s areas are identifiable in humans?

A

43

1-12; 17-43; 48-52

missing 13-16 & 44-47

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17
Q

primary cortical region v. associative cortical region

A

primary: directly receives input OR directly instructs/controls lower motor neuron
associative: process & integrate information from one or more primary regions

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18
Q

how are associative cortical regions divided?

A

by modality

unimodal: recieves input from a single primary cortex
heteromodal: integrates abstract sensory & motor info together w/motivational & emotional influences

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19
Q

what is somatotopy?

A

which region of the primary motor or sensory cortex controls a region of the body

point for point correspondance for an area of the body to a specific point w/in primary cortex (either somatosensory or motor)

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20
Q

why is somatotopy clinically important?

A

because pain or paralysis in a certain body region can be correlated to a certain point in the primary somatosenory cortex or primary motor cortex respectively

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21
Q

cell bodies in the CNS

A

nuclei

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22
Q

axons in the CNS

A

tracts

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23
Q

comissures

A

bundles of axons that connect the right & left sides of the brain

corpus callosum

anterior & posterior comissures

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24
Q

decussations

A

crossings

we do not know why axons cross over

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25
Q

rostral

A

front of brain

OR

superior of brainstem

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26
Q

ventral

A

inferior of brain

OR

frontal/belly side of brainstem

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27
Q

caudal

A

posterior or back of brain

OR

inferior of brainstem

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28
Q

dorsal

A

top of brain

OR

back/posterior of brainstem

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29
Q

why is the orientation of the brain different than the rest of the body?

A

because of neural tube folding

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30
Q

axial plane

A

transverse

cuts from face to posterior

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31
Q

coronal plane

A

cuts dorsal (crown) to ventral

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32
Q

sagittal plane

A

cuts left & right (not necessarily equal portions)

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33
Q

why does white matter appear dark in spinal cord sections?

A

b/c they are stained for myelin

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34
Q

where is white matter found?

A

internal in the brain and cortically (external) in spinal cord

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35
Q

where is gray matter found?

A

brain cortex & internal spinal cord

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36
Q

why is white matter white?

A

myelin: high lipid content

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37
Q

the major of nerve degeneration occurs in the …..

A

anterograde direction

nerve segment distal to injury site degenerates

aka Wallerian degeneration

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38
Q

why do CNS tracts not regenerate?

A

partly due to inhibitory proteins expressed by oligodendrocytes

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39
Q

structure & function of meninges

A

dura mater (double layer in brain, single in spinal cord): dense connective tissue

arachnoid mater

pia mater (attached to surface of brain/spinal cord): loose connective tissue

function to protect CNS

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40
Q

which layer of the meninges is sensitive to pain?

A

dura mater

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41
Q

which layer of dura is semitransparent?

A

arachnoid mater

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42
Q

which layer is avascular?

A

arachnoid mater

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43
Q

which layer of the meninges has its own blood supply?

A

dura mater

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44
Q

name the dura septa

A

falx cerebri

falx cerebelli

tentorium cerebelli

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45
Q

what is the tentorial notch?

A

opening formed by the tentorium cerebelli

surrounds midbrain

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46
Q

what is the function of the dura septa?

A

separate cranial cavity into compartments

restrict brain from displacement

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47
Q

name the major dural venous sinuses

A

superior sagittal sinus

straight sinus

transverse sinus

sigmoid sinus

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48
Q

name the minor venous sinuses

A

inferior sagittal sinus

occipital sinus

inferior petrosal sinus (L&R)

superior petrosal sinus (L&R)

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49
Q

function of dural venous sinuses

A

receive blood from veins of brain & CSF from subarachnoid space

empties all into internal jugular vein

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50
Q

where is the CSF found?

A

in the subarachnoid space

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51
Q

function of arachnoid trabeculae

A

extensions of arachnoid mater to pia

to help keep brain suspended w/in cavity

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52
Q

how does the CSF get from the subarachnoid space to the dural venous sinuses?

A

via arachnoid villi

large villi are refered to as arachnoid granulations

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53
Q

characteristics of epidural hematomas

A
  • convex shape
  • stops at boney sutures
  • expands inward
  • meningeal artery bleed or dural venous sinus bleed
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54
Q

characteristics of subdural hematomas

A
  • cresent shape
  • stops at dural reflections
  • expands along the skull
  • do not cross midline
  • bleed of vein at attachment to sinus or dural venous sinus bleed
  • may shift midline structures
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55
Q

what are the symptoms of hydrocephalus?

A
  • downcast eyes
  • irritability
  • seizures
  • vomitting
  • drowsiness
  • separating sutures
  • bulging at fontanelles (infants only)
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56
Q

how are the lateral ventricles connected to the third ventricle?

A

interventricular formina

(aka formen of Monro)

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57
Q

how does the 3rd ventricle communicate w/the 4th ventricle?

A

via the cerebral aqueduct (aka aqueduct of Sylvius)

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58
Q

name the five regions of the lateral ventricles

A

anterior horn

body

antrum

posterior horn

inferior horn

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59
Q

how do the cranial & spinal dura mater compare?

A

cranial: double layer= skull periosteum + cranial dura (contiguous w/spinal)
spinal: single layer suspended in vertebral canal

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60
Q

how do the cranial & spinal epidural spaces compare?

A

cranial: “potential” space
spinal: real space

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61
Q

how does the pia mater of the cranium & spinal regions compare?

A

spinal includes denticulate ligaments that expand outward to attach to spinal dura mater

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62
Q

effect of bleeding cerebral artery or vein

A
  • subarachnoid
  • intraparenchymal
    • 10% cause stroke
    • increased disability or death
    • can cause potentially fatal herniation
  • intraventricular hemorrhage
    • bleeding in ventricular system
    • result from physical trauma or hemorrhaging stroke
    • 35% of moderate-severe traumatic brain injuries
    • can lead to potentially fatal hernation
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63
Q

why is there a dounut hole in the third ventricle?

A

corresponds to the interthalamic adhesion

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64
Q

what does the median aperature connect?

A

4th ventricle to the cerebellomedullary cistern

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65
Q

what does the lateral aperature connect?

A

aka foramen of Luschka

bilateral

4th ventricle to quadrigeminal cistern

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66
Q

functions of CSF

A

mechanical support for brain

protection from pressure changes

controls brain excitiability by regulation ionic composition

removes metabolites

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67
Q

CSF circulation

A
  • choroid plexus
  • venricles
  • subarchnoid space
  • arachnoid villi/granulations
  • sinuses
  • internal jugular vein
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68
Q

choroid plexuses

A

projections of pia mater into ventricles

develop in ventricles

highly vascularized

make CSF

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69
Q

where is an adult lunbar puncture prerformed?

A

L3/L4

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70
Q

where is a lumbar puncture performed on a child?

A

L4/L5

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71
Q

which sinuses converge at the confluence of sinuses?

A

superior sagittal, straight, & transverse sinuses

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72
Q

which sinus drains into the internal jugular vein?

A

sigmois sinus

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73
Q

where does the superior petrosal sinus drain?

A

into the transverse sinus

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74
Q

where does the inferior petrosal sinus drain?

A

internal jugular vein

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75
Q

what is a cistern?

A

widened areas of the subarachnoid space between arachnoid & pia maters

filled w/CSF

4 main cisterns in the brain

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76
Q

name the main cisterns

A
  • interpeduncular: base of cerebral hemispheres, between temporal lobes
    • contains optic chiasm
  • pontine: surrounds anterior aspect of pons
  • quadrigeminal: posterior to midbrain
  • cerebellomedullary: largest; lies between cerebellum & medulla
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77
Q

causes of brain herniation

A
  • pressure from a hematoma
  • pressure from an expanding mass in a temporal lobe
  • pressure from expanding mass in cerebellum
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78
Q

tonsilar hernation

A

tonsil of medulla hernates thru the foramen magnum

compresses medulla→ contains respiratory & CV centers

usually rapidly fatal

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79
Q

uncal herniation

A

medial temporal lobe aka uncus herniates thru the tentorial notch

compression of midbrain→ contains structures for consciousness

typically causes coma & often death

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80
Q

subfalcine herniation

A

cingulate gyrus herniates under falx cerebri

presses on opposite cingulate gyrus

no serious neurological consequences

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81
Q

cause of communicating hydrocephalus

A

impaired CSF reabsorption

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82
Q

how is the neocortex arranged?

A

aka cortex of cerebrum

in 6 layers

I is outermost & VI is innermost

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83
Q

betz cells

A

specialized pyramidal cells in layer V of primary motor cortex

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84
Q

what is the input to layers I-III?

A

from cortex

outputs to other areas or cortex

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85
Q

what is the input to layer IV?

A

from the thalamus

thus this layer is enlarged in the primary somatosensory cortex

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86
Q

what is the output rom layer V?

A

to striatum, brainstem & spinal cord

thus this layer is enlarged in the primary motor cortex

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87
Q

where does layer VI output to?

A

thalamus

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88
Q

what are pyramidal neurons?

A

dendrites contain spines which are preferential for synaptic contact

long axons in cortical or subcortical areas

glutamatergic synapses

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89
Q

where are pyramidal neurons concentrated in the cortex?

A

layers II, III, V, & VI

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90
Q

function of cortical interneurons

A

local control

via GABAergic synapses

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91
Q

what is the difference between granular & agranular neocortex?

A

granular is well developed layer 4

agranular is no apparent layer 4

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92
Q

what are the granular regions?

A

prefrontal cortex (8, 9, 10)

aka primary somatosensory cortex

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93
Q

what are the major agranular regions?

A

primary motor (4) & premotor (6) cortices

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94
Q

what are association fibers?

A

axons of pyramidal neurons from layers II & III

connect different cortical areas in one hemisphere

bidirectional

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95
Q

types of association fibers

A

arcuate fibers

superior longitudinal fasciculus

arcuate fasicculus

uncinate fasciculus

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96
Q

what do the arcuate fibers connect?

A

adjacent gyri

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97
Q

what does the superior longitudinal fasciculus connect?

A

rostal to caudal length of hemisphere

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98
Q

what does the arcuate fasciculus connect?

A

caudal temporal & inferior parietal to frontal lobe

part of the superior longitudinal fasciculus

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99
Q

what does the uncinate fasciculus connect?

A

temporal to frontal lobes

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100
Q

funtion of commissures

A

connect homologous areas of two hemispheres

also from axons of pyramidal cells from layers II & III

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101
Q

name the main commissures

A

corpus callosum

anterior commissure

posterior commissure

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102
Q

what does the anterior commissure connect?

A

olfactory nuclei

amygdalas

anterior temporal lobes

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103
Q

what does the posterior commissure connect?

A

pretectal nuclei for pupillary reflex

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104
Q

what does the corpus callosum connect?

A

genu connects anterior frontal lobes

body connects posterior frontal lobes, parietal lobes, & superior temporal lobes

splenium connects occipital lobes

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105
Q

what are projection fibers?

A

connect cortex to subcortical brainstem & spinal cord targets

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106
Q

what layer of the cortex do the projection fibers originate?

A

layer V

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107
Q

what tracts are carried in the anterior limb of the internal capsule?

A

frontopontine fibers& thalamocortical fibers

connect medial & anterior nuclei of thalamus to frontal lobes

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108
Q

what tracts are carried w/in the genu of the internal capsule?

A

mostly corticobulbar & some thalamocortical fibers

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109
Q

what tracts are carried in teh posterior limb of the internal capsule?

A

mainly corticospinal fibers

some medial lemniscus fibers & spinothalamic fibers

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110
Q

corticofugal

A

away form the cortex

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111
Q

corticopetal

A

toward the cortex

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112
Q

when does neurogenesis occur?

A

prenatally

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113
Q

when does migration occur?

A

prenatally

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114
Q

when does arborization occur?

A

starts prenatally & continues thru early adulthood (23)

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115
Q

when does myelination occur?

A

starts prenatally but continues into early adulthood (23)

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116
Q

when does synapse formation occur?

A

throughout life

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117
Q

when does synpase elimination occur?

A

throughout life

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118
Q

where are neurons “born”?

A

ventricular zone

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119
Q

how do newly formed neurons migrate to the cortex?

A

climbing on strands of radial glia cells from ependymal to pial surface

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120
Q

what are radial glia cells?

A

neuronal progenitors that divide & give rise to daughter cells that use the mother to migrate to the cortex

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121
Q

the newest neurons deposit where?

A

on top

nearest the pia

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122
Q

filamin

A

taking the train

initiation of migration of neurons

actin-binding protein

important for signaling scaffolds

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123
Q

periventricular heterotopia

A

filamin mutation

FLNA gene

X-linked, dominant

males usually die in utero

neurons collect near walls of ventricles instead of migrating to the cortex

intelligence is often normal or mildly compromised

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124
Q

doublecortin

A

staying on board

microtubule associated protein

important for proper migration

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125
Q

LISX1

A

Lissencephaly X-linked 1

doublecortin (DCX) gene mutation

smooth brain w/no gyri (lissencephaly)

or pachygyria (fewer than normal gyri)

severe retardation

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126
Q

subcortical laminar band heterotopia

A

SBH

double cortex: band of gray matter from neurons terminating their migration prematurely

heterzygote females for doublecortin mutation

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127
Q

Reelin

A

getting on the train

extracellular matrix protein

important for cell-cell interactions & termination of migrating neurons

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128
Q

what cells secrete Reelin to the extracellular space?

A

Cajal-Retzius cells in layer 1

accumulates just below pial surface

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129
Q

LIS2

A

reelin mutation on chromosome 7

earlier born neurons stay attached to radial glia fiber & block migration of later born neurons

lissencephaly type 2

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130
Q

Norman-Roberts Syndrome

A

inverted cortical lamination: younger neurons deeper to older ones

underdevelopment of cerebellum & craniofacial abnormalities

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131
Q

Miller-Dieker Syndrome

A

autosomal dominant disorder

cause type 1 lissencephaly (smooth brain)

severe mental retardation

cortex has 4 layers instead of 6

not usually passed on b/c affected die in infancy or childhood

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132
Q

LIS1

A

on chromosome 17

codes for protein that maintanes proper speed of migration

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133
Q

neural pruning

A

overproduction of neurons forces them to compete for neurotrophic factors

only those that receive sufficient quantities survive

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134
Q

maturation sequence of cortex

A

primary & unimodal cortical areas mature first (around puberty)

prefrontal & parietal multimodal areas end around 20yrs

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135
Q

where does adult neurogenesis occur?

A

only in the hippocampus & olfactory bulb

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136
Q

how does adult & embryonic neurogenesis differ?

A
  • # few thousand/day v. millions or billions
  • generated from stem cells v. derived from glia under environmental influences
  • migrate thru existing white matter to specific areas v. on radial glia
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137
Q

CN I

A

olfactory nerve

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138
Q

CN II

A

optic nerve

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139
Q

CN III

A

oculomotor nerve

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140
Q

CN IV

A

trochlear nerve

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141
Q

CN V

A

trigeminal nerve

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142
Q

CN VI

A

abducens nerve

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143
Q

CN VII

A

facial nerve

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144
Q

CN VIII

A

vestibulocochlear nerve

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145
Q

CN IX

A

glossopharyngeal

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146
Q

CN X

A

vagus

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147
Q

CN XI

A

spinal accessory nerve

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148
Q

CN XII

A

hypoglossal nerve

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149
Q

brainstem nuclei associated with CN III

A

oculomotor nucleus & Edinger-Westphal nucleus

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150
Q

brainstem nuclei associated with CN IV

A

trochlear nucleus

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151
Q

brainstem nuclei associated with CN V

A

motor nucleus of V

main sensory nucleus of V

spinal nucleus of V

mesencephalic nucleus

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152
Q

brainstem nuclei associated with CN VI

A

abducens nucleus

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153
Q

brainstem nucleus associated with CN VII

A

facial nucleus

superior salivary nucleus

nucleus solitarius

main sensory nucleus of V

spinal nucleus of V

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154
Q

brainstem nuclei associated with CN VIII

A

vestibular nucleus

cochlear nucleus

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155
Q

brainstem nuclei associated with CN IX

A

nucleus solitarius

nucleus ambiguus

inferior salivary nucleus

main sensory nucleus of V

spinal nucleus of V

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156
Q

brainstem nuclei associated with CN X

A

dorsal motor nucleus of X

nucleus solitarius

nucleus ambiguus

main sensory nucleus of V

spinal nucleus of V

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157
Q

brainstem nuclei associated with CN XI

A

accessory nucleus

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158
Q

brainstem nuclei associated with CN XII

A

hypoglossal nucleus

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159
Q

GSA

A

general somatic afferent

general sensation: pain, touch, pressure, temp. & proprioception

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160
Q

GSE

A

general somatic efferent

voluntary motor

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161
Q

GVA

A

general visceral afferent

sensation from viscera

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162
Q

GVE

A

general visceral efferent

motor fibers to smooth muscle, glands, & viscera

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163
Q

BE

A

branchial efferent

aka SVE: special visceral efferent

motor fibers to skeletal muscle formed from pharyngeal (branchial) arches

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164
Q

SVA

A

special visceral afferent

taste & smell

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165
Q

SSA

A

special sensory afferent

sight & Sound

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166
Q

which cranial nerve carry GSA fibers?

A

V

VII

IX

X

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167
Q

which CNs carry GSE fibers?

A

III

IV

VI

XI

XII

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168
Q

which CNs carry GVA?

A

V

VII

IX

X

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169
Q

which CNs carry GVE fibers?

A

III

VII

XI

X

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170
Q

which CNs carry BE fibers?

A

V

VII

IX

X

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171
Q

whic CNs carry SVA fibers?

A

smell: I
taste: VII, IX, & X

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172
Q

which CNs carry SSA fibers?

A

vision: II
hearing: VIII

balance/equilibrium: VIII

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173
Q

CN, modality, & innervation of oculomotor nucleus

A

CN III: oculomotor

GSE: voluntary motor

of superior rectus, inferior rectus, medial rectus, inferior oblique

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174
Q

CN, modality, & innervation of Edinger-Westphal nucleus

A

CN III: oculomotor

GVE: visceral motor

ciliary muscle for pupillary reflex

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175
Q

CN, modality, & innervation of trochlear nucleus

A

CN IV: trochlear nerve

GSE: voluntary motor

of superior oblique m. of the eye

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176
Q

CN, modality, & innervation of motor nucleus of V

A

CN V: trigeminal nerve

BE: voluntary motor

muscle of mastication: temporalis, massester, & lateral pterygoid

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177
Q

CN, modality, & innervation of main sensory nucleus of V

A

CN V: trigeminal nerve

GSA

touch from face

**GSA fibers from VII for touch from skin posterior to ear**

**GSA touch fibers of CN IX from middle ear**

**GSA touch fibers of CN X**

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178
Q

CN, modality, & innervation of spinal nucleus of V

A

CN V: trigeminal

GSA

pain from face

**GSA fibers of VII for pain from skin posterior to ear**

**GSA pain fibers of CN IX for middle ear**

**GSA pain fibers of CN X**

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179
Q

CN, modality, & innervation of mesencephalic nucleus

A

CN V: trigeminal

GSA

proprioception from face

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180
Q

CN, modality, & innervation of abducens nucleus

A

CN VI: abducens nerve

GSE: voluntary motor

of lateral rectus muscle of the eye

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181
Q

CN, modality, & innervation of facial nucleus

A

CN VII: facial nerve

BE: voluntary motor

of muscles of facial expression & stapedius m.

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182
Q

CN, modality, & innervation of superior salivary nucleus

A

CN VII: facial nerve

GVE

to lacrimal, submandibular, & sublingual glands (& glands innervated by branches of pterygopalatine ganglion)

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183
Q

CN, modality, & innervation of nucleus solitarus

A

CN VII: facial nerve

rostal: GSA→ taste 2/3 of tongue
caudal: GVA→ skin posterior to ear

**also carries SVA taste (posterior 1/3 of tongue) & GSA fibers (tonsils & oropharynx) of CN IX**

**also carries SVA taste (epiglottic regions) & GVA (aortic chemo-& baroreceptors, thoracic & abdominal viscera) of CN X***

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184
Q

CN, modality, & innervation of vestibular nucleus

A

CN VIII: vestibulocochlear nerve

SSA

balance & equilbrium

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185
Q

CN, modality, & innervation of cochlear nucleus

A

CN VIII: vestibulocochlear nerve

SSA

hearing

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186
Q

CN, modality, & innervation of nucleus ambiguus

A

CN IX: glosspharyngeal nerve

BE: voluntary motor

to stylopharyngeus muscle

**also carries BE (vountary motor) fibers from CN X for innervation of larynx, pharynx, & palate**

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187
Q

CN, modality, & innervation of inferior salivary nucleus

A

CN IX: glossopharyngeal nerve

GVE: visceral motor

to parotid gland

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188
Q

CN, modality, & innervation of dorsal motor nucleus of X

A

CN X: vagus nerve

GVE: visceral motor

mainly to thoracic & abdominal viscera

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189
Q

CN, modality, & innervation of accessory nucleus

A

CN XI: accessory nerve

GSE: voluntary motor

to sternocleidomastoid & trapezius

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190
Q

CN, modality, & innervation of hypoglossal nucleus

A

CN XII: hypoglossal nerve

GSE: voluntary motor

of tongue muscles: genioglossus, hyoglossus, styloglossus, geniohyoid, thyrohyoid

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191
Q

which nuclei are found in the midbrain?

A

CN III & IV

oculomotor

Edinger-Westphal

trochlear

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192
Q

which nuclei are found in the Pons?

A

motor nucleus of V (BE)

Main sensory nucleus of V (GSA)

mesencephalic nucleus (CN V)

abducens nucleus (CN VI)

facial nucleus (CN VII-BE)

superior salivary nucleus (CN VII-GVE)

nucleus solitarius (CN VII)

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193
Q

which nuclei are found in the medulla?

A

spinal nucleus of V

vestibular nucleus (CN VIII)

cochlear nucleus (CN VIII)

inferior salivary nucleus (CN IX)

nucleus ambiguus (CN IX)

dorsal motor nucleus of X

hypoglossal nucleus (CN XII)

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194
Q

where does the conus medullaris end in adults?

A

L1/L2 vertebral level

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195
Q

where does the conus medullaris end in newborns?

A

L3 vertebral level

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196
Q

where are the preganglionic parasympathetic cell bodies located?

A

cranial nerves III, VII, IX, & X

S2-S4 vertebral levels of the spinal cord

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197
Q

why is there an enlargement of the lateral horn in the cervical spinal cord?

A

due to the LMN cell bodies that send out axons to innervate the upper limbs

similarly found in the lumbar region for innervation of the lower limbs

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198
Q

what vertebral levels correspond to the cervical enlargement?

A

C5-T1

brachial plexus

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199
Q

what vertebral levels correspond to the lumbar enlargement?

A

L1-S3

lumbosacral plexus

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200
Q

what tracts make up the posterior funiculus?

A

aka dorsal column

fasciculus gracilis & fasiculus cuneatus

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201
Q

main areas of spinal grey matter

A

dorsal horn

intermediate horn/zone

ventral horn

anterior white commissure

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202
Q

how is the grey matter organized in the spinal cord?

A

nuclei/nuclear groups

OR

Rexed Laminae: 10 cytoarchitectonic layers

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203
Q

Rexed’s Laminae

A

I-VI in dorsal horn

VII in intermediate zone

IX motor cell columns

X central grey

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204
Q

lamina I

A

marginal layer

posteromarginal nucleus

mostly nociceptive (pain)-specific neurons

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205
Q

lamina II

A

substantia gelatinosa

almost exclusively interneurons

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206
Q

what lamina corresponds to the nucleus proprius?

A

lamina III, IV, & V

mostly nonnoxious stimuli, proprioception

lamina V has a dyanmic range

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207
Q

lamina VI

A

lateral neurons receive corticospinal & rubrospinal fibers

medial neurons receive afferents form muscle spindles & joints for stretch, tension and length reception

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208
Q

intermediolateral nuclei

A

lamina VII

lateral horn/zone

neurons that respond to noxious & more complex properties

sympathetic neurons T1-L2

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209
Q

lamina IX

A

alpha-motor neurons

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210
Q

where is Clarke’s column located?

A

in the intermediate zone of spinal grey matter medial to the lateral horn/preganglionic sympathetic cell bodies

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211
Q

what type of information is carried by Clarke’s column?

A

unconscious proprooception to the cerebellum

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212
Q

how are the LMN cell bodies arranged w/in the ventral horn?

A

cells supplying proximal musculature are medial to those supplying distal musculature

cells supplying flexors are dorsal & extensors are ventral

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213
Q

where are the LMN nuclei supplying the facial muscles found?

A

brainstem

more specifically facial nucleus found in facial colliculus on the dorsal aspect of the pons

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214
Q

signs & symptoms of UMN lesion

A

upper mean things go up

spastic paralysis

hypereflexia

hypertonia w/spasticity

Babinski’s sign present

muscle weakness (paresis)

large area

decreased speed of movement

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215
Q

signs & symptoms of LMN lesions

A

lower things lessen

flaccid paralysis

arflexia or hyporeflexia

twitching (reduced muscular tone)

pronounced atrophy

complete loss of movement

area is localized

Babinski’s sign is absent

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216
Q

why do newborns display Babinski’s sign?

A

because the corticospinal pathway is not yet fully myelinated

thus the reflex is not inhibited by the cortex

disappears as they learn to walk around 12-18 months

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217
Q

complete cord transection

A
  • compression or transverse lesion of entire spinal cord
  • clinical features: all below level of spinal injury
    • loss of touch/vibration/proprioception
    • loss of pain & temp sensation
    • loss of voluntary motor
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218
Q

Brown-Sequard Syndrome

A
  • compression or lesion of one side (1/2) of spinal cord
  • clinical features: below level of injury
    • loss of motor on ipsilateral side
    • loss of touch/vibration/proprioception on ipsilateral side
    • loss of pain & temp on ipsilateral side at level of injury
    • loss of pain & temp on contralateral side below level of injury
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219
Q

syringomyelia

A
  • cyst or cavity formation in spinal cord
    • usually in cervical region
    • due to enlargement of central canal
  • clinical features
    • loss of pain & temp sensation over neck, shoulders, & arms
      • due to destruction of anterior white commissure
    • possible weakness & atrophy of hands & arms if damage extends into anterior horns
    • usually spares touch/vibration sensations
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220
Q

cause of subacute combine degeneration of the spinal cord

A

B12 deficiency

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221
Q

clinical features of subacute combined degeneration of the spinal cord

A
  • bilateral spastic paralysis due to lateral corticospinal axon degeneration
  • bilateral loss of touch/vibration/proprioception due to dorsal column degeneration
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222
Q

mechanism of ALS

A

ALS= amyotrophic lateral sclerosis (Lou Gehrig’s Dz)

Upper & lower motor neurons degeneration throughout CNS

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223
Q

how does ALS initially present?

A

weakness in a single limb

then spreads to opposite

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224
Q

clinical features of ALS

A
  • combination of weakness & atrophy of limb muscles
  • cramping & fasciculations (twitching) in limbs
  • general hypereflexia
  • flaccid paralysis at level of lesion
  • spastic paralysis below level of lesion
  • problems w/swallowing (dysphagia), breathing (dyspnea), & speaking (dysarthria)
  • sensory neurons/tracts unaffected
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225
Q

tabes dorsalis

A
  • caused by tertiary syphilis (neurosyphilis)
  • destroys large diameter dorsal root fibers & DRG
    • usually in lumbosacral region
  • clinical features:
    • lightning pain
      • likely resulting from incomplete dorsal root lesions
    • ataxia
    • areflexia
    • hypotonia
    • bladder malfunction
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226
Q

describe anatomy of a reflex arc.

A
  1. sense organ: muscle spindle
  2. Ia afferent sensory neuron
  3. one or more synapses w/in central integrating station in spinal cord
  4. efferent alpha-motor neuron
  5. effector: muscle fibers
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227
Q

define mysotatic reflex

A

aka stretch or deep tendon reflex

tonic contraction of muscles in response to a stretching force, due to stimulation of muscle proprioception

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228
Q

what do alpha motor neurons innervate?

A

extrafusal msucle fibers

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229
Q

what do gamma-motor neurons innervate?

A

intrafusal muscel fibers: muscle fibers w/in the muscle spindle

regulates sensitivity of muscle spindle so it can be maintaned during contraction

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230
Q

mechanism of deep tendon reflex

A
  1. group Ia sensory afferent fiber sense stretch in muscle spindle
  2. signal travels to cell body in DRG
  3. Ia axon synapses on alpha motor neuron in ventral horn
  4. alpha motor neuron activates muscle fibers

ex. knee-jerk reflex

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231
Q

what is reciprocal inhibition?

A

contraciton of one muscel set accompanied by relaxation of antagonist muscle

via inhibitor interneuron between 1a afferent axon & alpha motor neuron of antagonist muscle

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232
Q

mechanism of Golgi tendon reflex

A
  • Ib afferent sensory axons acts as proprioceptive/strain gauge
    • located in tendons (muscle to bone cxn)
  • Ib stimulation activates inhibitory interneuron in intermediate zone of spinal cord
  • alpha motor is inhibited
  • muscle relaxes
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233
Q

mechanism of withdrawl reflex

A
  1. pain axon stimulates excitatory interneurons that excite flexors
  2. pain axon stimulates inhibitory interneurons that relax extensors
  3. crossed-extensor reflex
    • pain axon stimulates excitatory interneurons that excite extensors on opposite leg
    • pain axon stimulates inhibitory interneurons that relax flexors on opposite leg
    • to balance & not fall over
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234
Q

axon reflex

A

hypothesized mechanism to explain teh spread of vasodilation in the vicinity of a localized region of cutaneous injury

impulse is relayed antidromically (opposite to normal direction)

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235
Q

clonus

A

series of involuntary muscular contractions due to sudden stretching of muscle

particularly associated w/UMN lesions

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236
Q

spinal shock

A

loss of sentation accompanied by motor paralysis w/initail loss but gradual recovery of reflexes, following spinal cord injury

initial weakened or absent reflexes followed by hyperrelexia (1-4 weeks later)

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237
Q

major branches of the internal carotid system

A
  • opthalmic
  • anterior cerebral artery
  • middle cerebral artery
  • posterior communicating artery
  • anterior choroidal artery
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238
Q

major branches of the vertebral-basiliar system

A

R+L vertebral arteries join to form basilar artery

PICAs (posterior inferior cerebellar arteries) branches from vertebral arteries

  • branches of basilar
    • anterior inferior cerebellar artery
    • superior cerebellar artery
    • posterior cerebral artery
    • paramedian pontine
    • long circumferential branch
    • short circumferential branch
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239
Q

blood supply to the spinal cord

A

2 posterior spinal arteries & 1 anterior spinal artery

posterior & anterior segmental medullary artiery that travel w/the dorsal & ventral root, respectively

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240
Q

effects of posterior spinal artery occusion/damage

A

loss of dorsal column

loss of discriminative touch, pressure, vibration, & proprioception from same side as arterial injury

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241
Q

effects of anterior spinal artery occlusion/damage

A
  • bilateral loss of pain & temp
    • due to spinothalamic axon disruption
  • bilateral paralysis
    • due to lateral corticospinal tract disruption
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242
Q

what does the anterior choroidal artery supply?

A

optic tract

some choroid plexus

part of the cerebral peduncle

portions of internal capsule, thalamus, & hippocampus

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243
Q

what does the middle cerebral artery supply?

A

travels thru the lateral sulcus to the lateral surface of the cerebrum

  • insula
  • most of lateral surface of cerebral hemisphere
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244
Q

where do the lenticulostriate branches come from & supply?

A

branches from middle cerebral artery

supplies deep structures→ basal ganglia (putamen, caudate nucleus, & globus pallidus) & internal capsule

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245
Q

why is language only affected if the left hemisphere is involved?

A

b/c 90% of people have language centers lateralized to the left hemisphere

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246
Q

what does the anterior cerebral artery supply?

A

travels along longitudinal fissure

supplies medial aspect of frontal & parietal lobes

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247
Q

effects of anterior cerebral artery occlusion

A

contralateral motor & somatosensory deficits to lower limb

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248
Q

Medial Medullary Syndrome

A

aka inferior alternating or Dejerine’s syndrome

occlusion of anterior spinal artery at level of medulla or medullary branches of vertebral artery

  • corticospinal tract: loss of voluntary motor function on contralateral side
  • medial lemniscus: loss of touch, vibration, pressure, & proprioception on contralateral side
  • hypoglossal nerve: loss of voluntary motor function on ipsilateral side of tongue
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249
Q

what does the posterior inferior cerebellar artery supply?

A

inferior surface of cerebellar hemispheres

lateral medulla

choroid plexus of 4th ventricle

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250
Q

Lateral Medullary Syndrome

A

aka Wallenberg’s Syndrome

occulsion of posterior inferior cerebellar artery or vertebral artery

  1. inferior cerebellar peduncle & vestibular nuclei→ ataxia, vertigo, nausea, nystagmus (involuntary eye movement)
  2. spinal tract of V & possible spinal nucleus of V→ ipsilateral pain & temp loss from face
  3. spinothalamic tract→ contralateral loss of pain & temp from body below neck
  4. descending sympathetic fibers→ ipsilateral Horner’s syndrome
  5. nucleus ambiguus (BE voluntary motor fibers to pharynx, larynx, & palate)→ hoarseness & dysphagia
  6. nucleus solitarius→ ipsilateral decreased taste
  7. cochlear nucleus→ ipsilateral hearing loss
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251
Q

Horner’s syndome

A
  • ptosis: drooping eyelid
  • miosis: impaired dilation of pupils (decreased pupil size)
  • anhydrosis: decreased sweating on ipsilateral face
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252
Q

what does the anterior inferior cerebellar artery supply?

A

anterior portions of inferior surface of cerebellum

parts of pons

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253
Q

where does the labyrinthe artery come from & supply?

A

branches from anterior inferior cerebellar artery

supplies inner ear

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254
Q

obstruction of what vessel causes vertigo & deafness?

A

labyrinthe

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255
Q

Lateral Pontine Syndrome

A

occlusion of anterior inferior cerebellar artery

  1. inferior cerebellar peduncle & vestibular nuclei→ ataxia, vertigo, nausea, nystagmus (involuntary eye movement)
  2. spinal tract of V & possible spinal nucleus of V→ ipsilateral pain & temp loss from face
  3. spinothalamic tract→ contralateral loss of pain & temp from body below neck
  4. descending sympathetic fibers→ ipsilateral Horner’s syndrome
  5. cochlear nucleus→ ipsilateral hearing loss
  6. facial nucleus→ loss of facial expression on ipsilateral side
  7. main sensory nucleus of V & motor nucleus of V→ ipsilateral loss of touch & muscles of mastication
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256
Q

what does the superior cerebellar artery supply?

A

superior surface of cerebellum & some midbrain

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257
Q

effects of superior cerebellar artery occlusion

A

ataxia

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258
Q

what does the posterior cerebral artery supply?

A

occiptal lobe→ visual centers

medial & inferior surfaces of occipital & temporal lobes

sends branches to midbrain & caudal diencephalon

gives rise to posterior choroidal arteries that supply choroid plexus of 3rd & lateral ventricles

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259
Q

Superior Alternating Syndrome

A

aka Weber’s or Medial Midbrain Syndrome

occlusion of posterior cerebral or basilar arteries

superior alternating hemiplegia= ipsilateral oculomotor nerve palsy & contralateral hemiplegia

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260
Q

Benedikt’s Syndrome

A

caused by: damage to ventral & lateral tegmental regions of midbrain

site of occlusion: posterior cerebral or basilar artery

clinical signs: oculomotor palsy, contralateral hemiplegia, ataxia, tremor, & involuntary movements (due to damage of red nucleus & superior cerebellar peduncle)

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261
Q

watershed zones

A

regions of brain that receive dual blood supply from branches of 2 major arteries

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262
Q

what forms the blood-brain barrier?

A

endothelial cells of CNS capillaries w/tight junctions

astrocytes produce signals that induce tight junction formation in the endothelial cells

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263
Q

what other structures are found at the cervicomedullary junction?

A

foramen magnum & pyramidal decussation

264
Q

what other structures are found at the midbrain-diencephalic junction?

A

tentorium cerebelli

265
Q

defining features of the caudal medulla

A

definied nucleus gracilis & nucleus cuneatus

circular shape

pyramidal decussation (dark stained axons in ventral portion)

266
Q

defining features of rostral medulla

A

inferior olivary nucleus

inferior cerebellar peduncle just lateral to inferior olivary nucleus

267
Q

defining feature of pons

A

pontocerebellar axons w/pontine nuclei

more caudally→ large middle cerebellar peduncles

268
Q

features of the caudal midbrain

A

cerebral peduncles dorsolaterally

superior colliculi

269
Q

what are the subdivisions of the diencephalon?

A
  1. epithalamus
  2. thalamus
  3. hypothalamus
  4. subthalamus (lateral to hypothalamus)
  5. metathalamus (not all texts)
270
Q

major anatomical divisions of thalamus

A

groupings of nuclei

  • anterior
  • medial
  • lateral
271
Q

functions of thalamus

A

sensory receiving area (all sensory pathways except olfactory)

relays sensory information to cerebral cortex

272
Q

major anatomical divisions of hypothalamus

A
273
Q

functions of hypothalamus

A

​HEAL

  • Homeostasis
  • Endocrine
  • Autonomic
  • Limbic
274
Q

describe relationship between hypothalamus & pituitary gland

A
275
Q

divisions of metathalamus & their functions

A
  • medial geniculate nucleus (body)
    • thalmaic relay between inferiro colliculus & auditory cortex
    • last switch of acoustic system before auditory cortex
  • lateral geniculate nucleus
    • last switch of optic system
    • optic tract ends here
276
Q

where is the hypothalamus found?

A

most ventral portion of diencephalon

277
Q

where is the subthalamus found?

A

inferior to the thalamus

between thalamus & tegmentum of midbrain

278
Q

where is the epithalamus found?

A

at the border of the diencephalon & mesencephalon

279
Q

components of epithalamus

A

pineal body

medial & lateral habenula (habenular nuclei)

habenular commissure

posterior commissure

280
Q

functions of the epithalamus

A
  • habenular nuclei
    • pain processing, reproductive behavior, nutrition, sleep-wake cycles, stress repsonses, & learning
    • linked to reward processing
  • pineal gland
    • melatonin production & secretion at night
    • biological timing & sleep induction
281
Q

where do the anterior thalamic nuclei receive information from?

A

mammillothalamic tract

282
Q

output of anterior thalamic nuclei

A

to cingulate gyrus & hypothalamus

283
Q

function of anterior thalamic nuclei

A

limbic

related w/emotional tone & mechanisms of recent memory

284
Q

presentation of anterior thalamic nuclei injury

A

diencephalic amnesia (similar to Korsakoff’s syndrome)

285
Q

input of medial dorsal thalamic nuclei

A

2-way connections w/ prefrontal cortex & hypothalamic nuclei

286
Q

output of medial dorsal thalamic nuclei

A

2-way connections w/ prefrontal cortex & hypothalamic nuclei

287
Q

function of medila dorsal thalamic nuclei

A

integration of large variety of sensory information (somatic, visceral, & olfactory)

& relation to emotional feelings

288
Q

presentation of medial dorsal thalamic nuclei injury

A

impair memory as with amnestic syndrome due to alcoholism

289
Q

lateral thalamic nuclei

A
  • dorsal tier
    • lateral dorsal nucleus
    • lateral posterio nucleus
    • pulvinar
  • ventral tier
    • ventral anterior nucleus
    • ventral lateral nucleus
    • ventral posterolateral nucleus (VPL)
    • ventral posteromedial nucleus (VPM)
290
Q

input & ouput of dorsal tier of lateral thalamic nuclei

A

NO subcortical connections

fibers project to cerebral cortex

291
Q

input & output of ventral anterior nucleus

A

in lateral thalamus

from denticulate nucleus of cerebellum

to motor cortex

292
Q

input & output of ventral lateral nucleus

A

in lateral thalamus

from denticulate nucleus of cerebellum

to motor cortex

293
Q

input & output of ventral posterolateral nucleus

A

in lateral thalamus

from medial lemniscus & spinothalamic tracts

to postcentral gyrus (primary somatosensory cortex)

294
Q

input & output of ventral posteromedial nucleus

A

in lateral thalamus

from trigeminal lemniscus & primary taste afferent from solitary tract

to postcentral gyrus AND to cortical gustatory area

295
Q

types of thalamic nuclei

A
  • relay
    • relay primary sensations (VPL, VPM, medial & lateral geniculate nuclei)
    • feedback of cerebellar signals (ventral lateral nucleus)
    • feedback of basal ganglia output (ventral anterior nucleus & part of ventral lateral)
  • association
    • receive from cerebral cotex & project back to cerebral cortex (pulvinar & dorsomedial nucleus)
  • non-specific
    • general alerting functions
    • intralaminar & midline thalamic nuclei
296
Q

thalamic syndrome

A

spontaneous pain on opposite side of body

may be aroused by light touch or cold

often fails to respond to powerful analgesics

caused by lesions of connection between VPM & VPL to the cortex

297
Q

how can the inferior colliculi be observed?

A

on a transverse cut of the rostal pons

298
Q

landmarks of the rostal midbrain

A

mammillary bodies (ventral)

thalamic nuclei (medial & lateral geniculate nuclei)

red nucleus (lateral to 3rd ventricle)

299
Q

modality of dorsal column/medial lemniscus pathway

A

GSA

for 2 point discrimination, pressure, vibration, & proprioception

from body below the nexk

300
Q

how many neurons in an ascending pathway?

A

3

301
Q

how many neurons are in a descending pathway?

A

2

302
Q

1st order neuron in the dorsal column pathway?

A

dorsal root ganglion

303
Q

2nd order neuron in the dorsal column pathway?

A

nucleus cuneatus for T6 and above

nucleus gracilis for T7 and below

304
Q

3rd order neuron for dorsal column pathway?

A

ventral posterolateral (VPL) nucleus of the thalamus

305
Q

tracts of the dorsal column

A
  1. fasciculus gracilis (or cuneatus) from DRG to nucleus gracilis (or cuneatus)
  2. medial lemniscus from nucleus gracilis & cuneatus to VPL of the thalamus
306
Q

where does the dorsal column pathway end?

A

layer 4 of the primary somatosensory cortex in the postcentral gyrus

307
Q

where are nucleus gracilis and nucleus cuneatus found?

A

caudal medulla

308
Q

where does the dorsal column pathway decussate?

A

caudal medulla

as internal arcuate fibers (just before becoming medial lemniscus)

309
Q

what is the somatotopic organization of the dorsal column?

A

lower structures are located more medially & upper structures more laterally

310
Q

modality of the anterior spinothalamic pathway

A

GSA

for crude touch

of the body below the neck

311
Q

modality of lateral spinothalamic pathway

A

GSA

for pain, noxious pressure, & temperature

from body below the neck

312
Q

1st order neuron of spinothalamic pathway

A

dorsal root ganglion

313
Q

2nd order neuron of spinothalamic pathway

A

dorsal horn of spinal cord

Lamina I: marginal layer

Lamina II: substantia gelatinosa

Lamina V: nucleus proprius

314
Q

tract between 1st & 2nd order neurons of spinothalamic tract

A

enter dorsal horn via Lissauer’s tract (can ascend 1-2 levels before synapse)

315
Q

3rd order neuron of spinothalamic tract

A

ventral posterolateral (VPL) of the thalamus

316
Q

tract between 2nd & 3rd order neurons of spinothalamic pathway

A

decussate im anterior white commissure & ascend as spinothalamic tract

317
Q

where does the spinothalamic pathway decussate?

A

at the level of the first synapse in the dorsal horn of the spinal cord

in the anterior white commissure

318
Q

what is the somatotopic organization of the spinothalamic tract?

A

upper body structure fibers are found more medial while lower body structure fibers are more lateral

319
Q

where does the spinothalamic pathway end?

A

primary somatosensory cortex

320
Q

where is the 1st order neuron of the corticospinal pathway?

A

upper motor neurons for anterior & lateral corticospinal pathways are in the primary motor cortex (precentral gyrus)

specifically Bets (pyramidal) cells of layer 5

321
Q

where does the lateral corticospinal pathway decussate?

A

in teh pyramids of the medulla

322
Q

where are the 2nd order neurons of the corticospinal pathways?

A

lower motor neurons are found in the ventral horn of the spinal cord

323
Q

modality of the lateral corticospinal pathway

A

GSE

for limbs

324
Q

hemiplegia

A

total or partial paralysis on one side of the body

325
Q

pathway of lateral corticospinal pathway from 1st to 2nd order neurons

A

travel via internal capsule thru cerebral peduncle, pons, & pyramids (decussation)

then descend in ventral horn of spinal cord

326
Q

where does the anterior corticospinal pathway decussate?

A

if they decussate it will be at the level of spinal cord that they will innervate

innervates bilaterally

decussation of axons of LMN

in cervical & thoracic spinal cord only

327
Q

modality of anterior corticospinal pathway

A

GSE

to axial & girdle muscles bilaterally

with contralateral predomination

328
Q

functions of subthalamus

A
  • component of motor system
    • connects basal ganglia
    • generation of rhythmic movements
  • neural control of micturition
329
Q

stimulation of the hypothalamus is an important treatment for what type of patients?

A

late stage parkinson’s patients

330
Q

what is the most ventral part of the diencephalon?

A

hypothalamus

331
Q

what is the most clinically significant part of the diencephalon & why?

A

hypothalamus

b/c a lesion in this area can resul

332
Q

function of the paraventricular nucleus

A

fluid balance (ADH)

milk let-down (oxytocin)

parturition (childbirth)

inegration of autonomic & control of anterior pituitary

333
Q

function of preoptic nuclei

A

control of ovulation (LH & FSH)

sexual behavior (sexually dimorphic nucleus)

334
Q

function of anterior nucleus of hypothalamus

A

temperature regulation

335
Q

how does the suprachiasmic nucleus complete its function?

A

function: biological rhythms

input form retina for light dark

output to pineal gland to release melatonin

336
Q

function of supraoptic nucleus

A

fluid balance

milk let-down

parturition

337
Q

function of dorsomedial nucleus

A

satiety (eating & drinking)

body-weight regulation

338
Q

lesion of what region can cause obesity?

A

dorsomedial nucleus

OR

ventromedial nucleus

339
Q

function of arcuate nucleus

A

control of anterior pituitary

production of hypothalamic releasing & inhibiting factors

340
Q

function of mammillary nucleus

A

emotion & short-term memory

341
Q

function of lateral complex

A

feeding center or increased eating

342
Q

lesion of what region can cause starvation?

A

lateral complex of the hypothalamus

343
Q

what region of the brain maintains homeostasis?

A

hypothalamus

  • neuroendocrine control of hormone release by pituitary gland
  • autonomic integration via direct projections to preganglionic autonomic neurons located in brainstem & spinal cord
  • interconnections w/limbic system for emotions & motivations
344
Q

what is the most important nucleus of the hypothalamus & why?

A

paraventricular nucleus

b/c it has directinfluence over both sympathetic & parasympathetic outflow systems

and receives from both as well

345
Q

functions of the hypothalamus

A
  1. blood pressure & electrolyte composition
    • thirst & salt appetite
  2. energy metabolism (feeding behavior)
  3. reproductive behaviors
  4. body temperture
  5. defense behavior
    • stress response & fight-or-flight response
  6. sleep-wake cycle
346
Q

what nucleus monitors chewing of food?

A

mesencephalic nucleus of V

347
Q

akinesia

A

absence or poor movement

348
Q

dyskinesia

A

fragmented or incomplete movement

349
Q

dystonia

A

disordered tonicity of muscle

350
Q

dysmetria

A

improper measuring of distance in muscular actions

overshoot or undershoot goal

351
Q

dysdiadochokinesia

A

impairment of ability to perform rapid alternating movements

352
Q

tremor

A

rhythmic involuntary movement

353
Q

ataxia

A

lack of finely tuned muscular movements involved in postural control

inability to coordinate voluntary movements

354
Q

arbor vitae

A

pattern of white pattern found in the cerebellum

355
Q

folia

A

gyri of cerebellum

356
Q

the primary fissure divides what structures?

A

anterior & posterior lobes of the cerebellum (appear more superior & inferior)

357
Q

what are the lobes of the cerebellum?

A

anterior lobe

posterior lobe

flocculonodular lobe

358
Q

where is the paleocerebellum?

A

aka spinocerebellum or intermediate zone

some of vermis & adjacent cortices of anterio & posterior lobes of cerebellum

359
Q

where is the pontocerebellum?

A

aka neocerebellum or lateral zone

majority of cerebellum

lateral portions of anterior & posterior lobes as well as central portion of the ventral aspect

360
Q

where is the vestibulocerebellum?

A

aka archicerebellum

flocculonodular lobe & some vermis

361
Q

function of paleocerebellum

A

aka spinocerebellum or intermediate zone

adjust ongoing movements & regulate muscle tone

362
Q

function of pontocerebellum

A

aka neocerebellum or lateral zone

coordinates planning of movements

363
Q

function of vestibulocerebellum

A

aka archicerebellum

controls balance & eye movements

364
Q

main input to the paleocerebellum

A

aka spinocerebellum or intermediate zone

spinocerebellar tracts

365
Q

main input to pontocerebellum

A

aka neocerebellum or lateral zone

sensory & motor cortices

366
Q

main input to vestibulocerebellum

A

aka archicerebellum

semicircular canals & vestibular nuclei

367
Q

Don’t Eat Greasy Foods

A
  • Dentate nucleus: works in pontocerebellar system
  • interposed nuclei
    • Emboliform nucleus
    • Globose nucleus
    • work in paleocerebellar system
  • Fastigial nucleus
    • works in vestibulocerebellar system
368
Q

how many layers are there in the cerebellar cortex?

A

3

369
Q

how many cell types are found in the cerebellar cortex?

A

5

370
Q

what is the innermost layer of the cerebellar cortex and what cell types are found there?

A

granule cell layer

Golgi cells

371
Q

Stellate cells are found in which layer of the cerebellar cortex?

A

molecular layer (outermost)

372
Q

which cells form the parallel fiber of the molecular layer?

A

granule cell axons

they travel up from the granule layer to teh surface of the molecular layer

373
Q

where and how to parallel fibers act?

A

excitatory on basket, stellate, & golgi cells

excitatory on purkinje cell dendrites in molecular layer

374
Q

where & how do basket cells act?

A

inhibitory on purkinje somas

375
Q

where & how do stellate cells act?

A

inhibitory on Purkinje cell dendritess in molecular layer

376
Q

where & how do the Golgi cells act?

A

inhibitory on mossy fibers in granule cell layer

377
Q

where & how do Purkinje cells act?

A

inhibitory on deep cerebellar nuclei

378
Q

what is the major output neuron of the cerebellar cortex?

A

Purkinje cells

379
Q

how do afferent axons enter the cerebellum?

A

mossy or climbing fibers

  • mossy fibers terminate as excitatory synapses on granule cell dendrites & provide info about movements
  • climbing fibers are from the inferior olivary nucleus (in caudal medulla) & terminate as excitatory synpases on smooth purkinje cells in the molecular layer
    • provides info about errors in execution of movement
380
Q

what synapses on the deep cerebellar nuclei are excitatory & which are inhibitory?

A

excitatory: mossy & climbing fibers
inhibitory: purkinje axons

381
Q

what is the first order neuron of the anterior spinocerebellar pathway?

A

DRG

382
Q

what is the tract from the first order to the second order neuron of the anterior spinocerebellar pathway?

A

axons travel with fasciculus gracilis

383
Q

what is the second order neuron of the anterior spinocerebellar pathway?

A

spinal border cells in lamina VII of the lumbar regions of the anterior horn

384
Q

what is the 3rd order neuron in the anterior spinocerebellar pathway?

A

paleocerebellum

385
Q

how do the axons of travel from the 2nd to 3rd order neurons in the spinocerebellar pathway?

A

cross in the anterior white commissure

via the anterior spinocerebellar tract in the anterior lateral funiculus

CROSS again in brainstem

thru superior cerebellar peduncle

386
Q

function of the anterior spinocerebellar pathway

A

transmit muscle spindle & Golgi tendon organ afferent information from DISTAL lower limbs to cerebellum

387
Q

first order neuron of posterir spinocerebellar pathway

A

DRG

388
Q

how do the axon fibers travel from the 1st to 2nd order neurons in the posterior spinocerebellar pathway?

A

with fasciculus gracilis

389
Q

what are the 2nd order neurons of the posterior spinocerebellar pathway?

A

Clarke’s Column (Nucleus) in T1-L2

390
Q

how do the axon fibers travel from the 2nd to 3rd order neurons in the posterior spinocerebellar pathway?

A

rostally via dorsal spinocerebellar tract in the lateral funiculus

then thru the inferior cerebellar peduncle

to paleocerebellum

391
Q

function of the posterior spinocerebellar pathway

A

transmits muscle spindle & Golgi tendon organ afferent info from trunk & proximal lower limb to cerebellum

392
Q

function of cuneocerebellar pathway

A

transmits muscle spindle & Golgi tendond organ afferent information from upper limb & neck to the cerebellum

393
Q

what is the first order neuron of the cuneocerebellar pathway?

A

DRG

394
Q

what is the second order neuron of the cuneocerebellar pathway?

A

lateral external cunate nucleus

395
Q

how do the fiber of the cuneocerebellar pathway travel from the 1st to 2nd order neuron?

A

with fasciculus cuneatus

396
Q

how do the fibers of the cuneocerebellar pathway travel from the 2nd to 3rd order neuron?

A

rostrally via cuneocerebellar tract

thru inferior cerebellar peduncle

to paleocerebellar region

397
Q

general function of the cerebellum

A

evaluate differences between intention & action

adjust operations in motor cortex & brainstem while a movement is in progress and during repetitions of the same movement

398
Q

how is the intended goal transmited to the cerebellum?

A

via corollary motor discharge

from motor centers to cerebellum

399
Q

how does the cerebellum know what the actual motor response was?

A

via sensory feedback from anterior and posterior spinocerebellar tracts and cuneocerebellar tract

400
Q

where do climbing fibers come from?

A

inferior olivary nucleus

401
Q

where do mossy fibers come from?

A

all fibers entering the cerebellum that aren’t from the inferior olivary nucleus are mossy fibers

402
Q

where do corollary fibers of the paleocerebellar system originate?

A

the red nucleus

travel via rubrospinal tract to intermediate zone of cerebellum

403
Q

where do corollary fibers of the pontocerebellar system originate?

A

corticospinal tract

to lateral zone or pontocerebellum

404
Q

where do corollary fibers of the vestibulocerebellar system originate?

A

from vestibulospinal tract

405
Q

where is the lesion in truncal ataxia?

A

vermis or flocculonodular lobe of the cerebellum

406
Q

where is the lesion in appendicular ataxia?

A

cerebellar hemispheres/lateral zone

407
Q

what does the Romberg test assess the function of?

A

proprioceptive system in dorsal column

408
Q

during a tandem gait test the patient the patient deviates to the left, where is the lesion?

A

left cerebellum

vermis or flocculonodular lobe as this is truncal ataxia

409
Q

finger-nose-finger test helps determine…

A

appendicular ataxia

410
Q

what motor pathways originate in the brain?

A

cotricospinal & corticobulbar tracts

411
Q

what motor pathways originate in the brainstem?

A

tectospinal tract

reticulospinal tract (lateral & medial)

rubrospinal tract

vestibulospinal tracts (lateral & medial)

412
Q

what are the clinical features of lacunar strokes?

A

contralateral hemiparesis

may be coupled w/various cranial nerve signs due to corticonuclear (or corticobulbar) fiber involvement

413
Q

where is the lesion that causes lacunar strokes?

A

internal capsule

414
Q

what syndrome produce contralateral hemiplegia w/ipsilateral paralysis of the tongue?

A

vascular lesions in medulla→ medial medullary syndrome (inferior alternating syndrome)

415
Q

what syndrome produce contralateral hemiplegia w/ipsilateral paralysis facial muscles or lateral rectus?

A

vascular lesion in pons

Millard-Gubler syndromes

416
Q

what syndrome produce contralateral hemiplegia w/ipsilateral paralysis of most eye movements?

A

vascular lesion in the midbrain

Weber’s syndrome/superior alternating syndrome

417
Q

where is the lesion if pt presents with bilateral paresis of upper limbs?

A

rostral portion of pyramidal decussation

418
Q

where is the lesion if pt presents w/bilateral paresis of lower limbs?

A

caudal portion of pyramidal decussation

419
Q

where is the lesion of the corticospinal fibers if pt presents w/ipselateral monoplegia?

A

unilateral thoracic cord damage

420
Q

what fibers occupy the caudal portions of the anterior limb of the internal capsule?

A

corticobulbar fibers from the frontal eye fields (middle frontal gyrus)

421
Q

corticobulbar fibers that pass thru the genu of the internal capsule originate where?

A

precentral gyrus (area 4/primary motor cortex)

422
Q

corticobulbar fibers from the postcentral gyrus travel thru which section of the internal capsule?

A

rostral poriton of the posterior limb

423
Q

where the do corticobulbar fibers synapse?

A

aka corticonuclear fibers

on ALL cranial nuclei

bilaterally on most

contralaterally on ventral cell group of CN VII supplying the facial muscles below the eyes & CN XII (to the tongue)

ipsilaterally to CN XI

424
Q

what are the clinical features of a lesion to the genu of the internal capsule?

A
  • contralateral paralysis of lower facial muscles (below eye)
    • upper facial muscles are spared
    • muscles of mastication are spared
  • nucleus ambiguus: dysphagia, dysarthria, ipsilateral deviation of uvula on phonation, hoarseness
  • deviation of tongue to contralateral side (hypoglossal nucleus)
  • unable to rotate head to contralateral side against resistance
  • unable to elevate shoulder on ispilateral side against resistance
425
Q

where is the lesion in supranuclear palsy?

A

unilateral lesion of facial region of primary motor cortex

UMN disorder

426
Q

where is the lesion in Bells Palsy?

A

compression or inflammation of the facial nerve or nucleus

LMN disorder

427
Q

where are the symptoms of Bells Palsy?

A

ipsilateral hemifacial muscles

428
Q

where are the symptoms in supranuclear palsy?

A

contralateral lower facial quadrant

429
Q

if there is a lesion to the UMN that synapses on the hypoglossal nucleus, which way will the tongue deviate?

A

away from the lesioned side

tongue is pushed by functioning muscles

430
Q

a lesion to the UMN that inervates CN XI leads to what clinical features?

A

unable to rotate head on contralateral side agianst resistance

unable to elevate shoulder on ipsilateral side against resistance

431
Q

why is there no deficit when a unilateral lesion to the UMN of CN V is present?

A

because the nucleus of V is innervated bilaterally with contralateral predominance

432
Q

what UMNs bilaterally innervate their cooresponding cranial nuclei with contralateral predominance?

A

CN V & X

433
Q

what are the most clinically relevant motor pathways from the brainstem?

A

medial reticulospinal

rubrospinal

lateral vestibulospinal

434
Q

what is the function of the medial reticulospinal pathway?

A

to enhance antigravity reflexes

fast voluntary or cortically induced movements

increases muscle tone via action on gamma motor neurons

excitatory to extensor motor neurons & to neurons innervating axial musculature

some may inhibit flexor motor neurons

435
Q

where does the tectospinal tract originate?

A

superior colliculus

436
Q

where does the tectospinal tract decussate?

A

dorsal tegemntal decussation

437
Q

where does the tectospinal tract terminate?

A

cervical spinal cord

in lamina VI, VII, & maybe VIII

438
Q

where does the medial reticulospinal tract decussate?

A

it does

it innervates ipsilaterally

439
Q

where does the medial reticulospinal tract originate?

A

pons

nucleus retcularis pontis oralis & nucleus reticuluaris pontis caudalis

440
Q

where does the medial reticulospinal tract terminate?

A

all spinal levels

in lamina VIII (sometimes VII & IX)

441
Q

where does the lateral reticulospinal tract originate?

A

medulla

nucelus reticularis gigantocellularis

442
Q

where does the lateral reticulospinal tract decussate?

A

partiall decussation in the medulla

443
Q

where does the lateral reticulospinal tract terminate?

A

lamina VII of all spinal levels

444
Q

what is the function of the lateral reticulospinal tract?

A

inhibit voluntary & cortically induced movements

decreases muscle tone via inhibiting muscle spindle activity thru action on gamma motor neurons

inhibitory to extensor motor neurons & neurons innervating muscles of neck & back

some fibers may excite flexor motor neurons

445
Q

where is the vestibular nucleus located?

A

dorsal medulla

446
Q

where is the red nucleus located?

A

ventral midbrain

447
Q

where does the rubrospinal tract originate?

A

red nucleus

caudal magnocellular part

448
Q

where does the lateral vestibulospinal tact originate?

A

lateral vestibular nucleus of the medulla

449
Q

where does the medial vestibulospinal tract originate?

A

medial vestibular nucleus

lateral vestibular nucleus

inferior vestibular nucleus

450
Q

where does the rubrospinal tract decussate?

A

midbrain

ventral tegmental decussation

451
Q

where does the lateral vestibulospinal tract decussate?

A

it doesn’t

452
Q

where does the medial vestibulospinal tract decussate?

A

partially crosses in medulla

453
Q

where does the rubrospinal tract terminate?

A

lamina V-VIII

of cervical spinal cord

454
Q

what is the function of the rubrospinal pathway?

A

facilitate motor neurons that innervate flexor muscles

functionally parallel to the corticospinal tract

455
Q

what is the function of the lateral vestibulospinal tract?

A

facilitate alpha and gamma motor neurons that innervate extensor muscles

maintain posture

modulate by activation of vestibular apparatus or cerebellum

456
Q

whre does the lateral vestibulospinal tract terminate?

A

all levels of the spinal cord

lamina VII & VIII

457
Q

where does the medial vestibulospinal tract terminate?

A

lamina VII & VIII

at cervical spinal levels

458
Q

what is the function of the medial vestibulospinal pathway?

A

causes rotation & lifting of head as well as rotation of shoulder blade

produces changes in posture & balance

459
Q

clinical features of decerebrate rigidity

A

all limbs extended

clenched jaw

neck retracted

460
Q

clinical features of decorticate rigidity

A

flexor posturing: arms flexed adducted), pronation of forearm, & legs and trunk extended

461
Q

where is the brain damage in decerebrate rigidity and what tracts are damaged?

A

midbrain

MR LV is intact

462
Q

where is the brain damage in decorticate rigidity and what tracts are damaged?

A

above the midbrain

rubrospinal tract intact

463
Q

what are the 4 main structures of the limbic system?

A

hypothalamus

olfactory cortex

hippocampus

amygdala

464
Q

what is the main function of the hippocampus?

A

memory

465
Q

what is the main funciton of the amygdala?

A

emotion

466
Q

what are the functions of the limbic system?

A

HOME

  • Homeostasis (hypothalamus)
  • Olfaction (olfactory cortex)
  • Memory (hippocampus)
  • Emotion (amygdala)
467
Q

what are the diencephalic components of the limbic system?

A

hypothalamus

nuclei in thalamus: anterior & dorsomedial

nuclei in epithalamus: Habenular

468
Q

what are the telencephalic components of the limbic system?

A

subcortical

allocortex

juxtallocortex (periallocortex)

469
Q

what are the basal forebrain nuclei?

A

septal nuclei: conenction w/hippocampus

diagonal band of Broca: connection w/hippocampus

nucleus basalis (of Maynert): projects to widespread areas of cortex

470
Q

where is the amygdala located?

A

rostral to the hippocampus

471
Q

the limbic system controls what five functions?

A

survival of species functions

  1. fight
  2. flight
  3. feeling
  4. feeding
  5. fornication
472
Q

what cortex only has three layers?

A

allocortex: hippocampus & olfactory cortex (uncus of temporal lobe)

473
Q

what cortex has 4-5 layers?

A

juxtallocortex aka periallocortex: entorhinal cortex, parahippocampal gyrus, cingulate cortex, & orbitofrontal cortex

474
Q

what are the inputs to the amygdala?

A

visual association cortex

auditory association cortex

somatosensory cortex

visceral cortex

hypothalamus

475
Q

how does the amygala effect the autonomic response?

A

via the hypothalamus

causes: tachycardia, increased respiration, & stress hormone release

476
Q

what causes Kluver-Bucy Syndrome?

A

large bilateral amygdaloid lesions

477
Q

what are the effects of Kluver-Bucy Syndrome?

A

wild, aggressive animals become placid & display hyper& inappropriate sexuality

unable to associate stimuli with rewards

visual agnosia: inability to recognize objects or faces

478
Q

what is the theoretical function of the basal forebrain nuclei?

A

to decide value or at least support the value of a memory for coding into long term storage

479
Q

what is the function of cholinergic neurons in the CNS?

A

attention, learning, & memory

480
Q

where is the hippocampus located?

A

along the posterior & inferior horns of the lateral ventricle

481
Q

describe Papez circuit

A
  • starts in hippocampus
  • axons travel thru fornix
  • synapse in mammillary bodies
  • travel to anterior nuclei of the thalamus via mammillothamalic tract
  • then to cingulate gyrus via internal capsule
  • cingulum bundle (axons from the cingulate gyrus) travels to parahippocampal
  • then to entorhinal cortex
  • entorhinal cortex communicates w/hippocampus
482
Q

what are the mesencephalic components of the limbic system and their functions?

A

ventral tegmental area (VTA): reward, motivation, & addiction systems (dopaminergic neurons)

nucleus accumbens: important for emotional staes relating to intense love & obsessive behaviors taht accompany rejected partners/friends

483
Q

types of long term memory

A

declarative & non-declarative

484
Q

what is semantic memory?

A

type of declarative memory

memory of meanings & understandings that do not involve a certain event

textbook facts

485
Q

what is episodic memory?

A

type of declarative memory

memory of life events

486
Q

what is declarative memory?

A

type of long-term memory

memory of facts: what, where, why

487
Q

what is non-declarative memory?

A

procedural memory: “how-to” knowledge

acquistion of this type of memory requires significant repetition

488
Q

what brain structures are involved in procedural memory?

A

basal ganglia

premotor cortex

cerebellum

489
Q

when is procedural memory most often affected?

A

damage to subcortical structures (basal ganglia)

Hunington’s & Parkinson’s

490
Q

what area of the brain is important for short-term memory?

A

prefrontal cortex

491
Q

stages of memory mechanism

A
  • encoding: process of storing info
  • storage: takes place in the cerebral cortex
  • retrieval: memory recall requires conscious cues to activate memory network & bring stored info to conscious level
  • forgetting
492
Q

why are things forgotten?

A
  • never consolidated
  • inability to retrieve/missing necessary cues for recall
  • interferenceform other memories
  • brain damage
493
Q

factors that inpact learning & memory

A

nutrition

stress

temperature

blood oxygen

sufficient sleep for optimal performance

494
Q

what structure is responsible for deciding what information should be stored as memories?

A

hippocampus

495
Q

what structures are required for memory consolidation?

A

hippocampus

entorhinal cortex

parahippocampal gyrus

mammillary bodies

medialdorsal nucleus of the thalamus

anterior nucleus of the thalamus

496
Q

purpose of Papez circuit

A

memory consolidation

497
Q

what synapse is important for long term potentiation?

A

from CA3 pyramidal cell to CA1 pyramidal cell

in hippocmapus

glutaminergic

via AMPA & NMDA receptors

increases AMPA receptors in postsynaptic membrane→ increased sensitivity to glutamate

postsynaptic release of NO→ increases ability of presynaptic release of glutamate

498
Q

what are the long term effects of long term potentiation?

A

protein kinases activate CREB (transcriptional regulator)

expression of genes that produce long lasting changes in synaptic structure

499
Q

what determines whether long term potentiation or depression occurs?

A

the amount of Ca2+ in the postsynaptic cell

small rises→ depression

large increases→ potentiation

500
Q

where are memories stored?

A

neocortex

501
Q

how do lesions in the fornix affect memory?

A

minor disruptions in function

502
Q

hoe do bilateral hippocampal lesions affect memory?

A

anterograde amnesia

cannot form new memories

503
Q

psychogenic amnesia

A

inability to recall episodes or personal information

usually due to traumatic, stressful or emotional experience

no apparent brain damage

unrelated to psychological emotional response

504
Q

transient global amnesia

A

temporary loss of memory

not related to any cause of condition

505
Q

In Alzheimer’s dz, what type of memory deficit is greatest?

A

semantic declarative memory compared to episodic declarative memory

506
Q

Wernicke’s encephalopathy

A

caused by thiamine deficiency

affects mammillary bodies, dorsomedial nucleus of thalamus, cerebellar vermis, CN III, CN IV, CN, VI, CN VIII

symptoms: encephalopathy, opthalmoplegia, & ataxia

507
Q

confabulation

A

distorted, fabricated, incorrect stories or memories

caused by dementia or brain damage

not liars, believe what they are saying is true

508
Q

once odorants bind to olfactory receptors, how is the signal sent to the olfactory tract?

A
  • olfactory receptor cells send signal to 2nd order neurons, mitral cells
  • synapse occurs at glomerulus
  • axons of mitral cells for the olfactory tract
509
Q

what cell performs lateral inhibitory action in the olfactory pathway?

A

granule cells & tufted cells

510
Q

axons of what cell type form the medial olfactory tract?

A

tufted & mitral cells

511
Q

axons of what cell type form the lateral olfactory tract?

A

tufted & mitral cells

512
Q

where does the medial olfactory travel to?

A

contralateral anterior olfactory nucleus

basal forebrain & limbic structures

513
Q

where does the lateral olfactory tract travel to?

A
  • piriform cortex
    • prefrontal cortex
    • thalamus
      • prefrontal cortex
  • amygdala
    • prefrontal cortex
  • entorhinal cortex
    • prefrontal cortex
    • hippocampus via the perforant pathway
514
Q

how many odorant receptor neurons are there and how do they effect the range of smell?

A

14 currently known

some are responsive to a single odorant, while others respond to different combinations of oderants

515
Q

what is the biochemical pathway of olfactory transduction?

A
  • GCPR GSalpha (adenylate cyclase activation)
  • cAMP opens Na+/Ca2+ channels
    • both ions enter olfactory receptor cell
  • Ca2+ opens Cl- channel
  • efflux of Cl- depolarizes the cell
  • generates an action potential
516
Q

what structures form the primary olfactory cortex?

A

in uncus of temporal lobe

amygdala

entorhinal cortex

piriform cortex

517
Q

where is the olfactory association cortex located?

A

orbital gyri of prefrontal cortex

518
Q

anosmia

A

loss of sense of smell

519
Q

hyposmia

A

decreased ability to smell

520
Q

hyperosmia

A

increased ability to smell

521
Q

dysosmia

A

distorted perception of odour

522
Q

phantosmia

A

perception of odour where there is none

523
Q

agnosmia

A

loss of verbal ability to classify, contrast and identify odour

sensation even though ability to detect & distinguish between odorants is present

524
Q

what factors lead to decline in olfactory ability?

A
  • age
  • head trauma
  • seizure
  • tumor
  • psychotic disorders
  • Alzheimer’s disease
525
Q

which papillae on the tongue have taste buds?

A

foliate (laterally)

vallate (posterior V)

fungiform

526
Q

how many and what types of cells are found w/in a taste bud?

A

3

receptor cells

columnar supporting cells

basal cells (can differentiate in other 2)

527
Q

which taste types act through ionotropic transmission and whic act through metabotropic transmission?

A

ionotropic: salty & sour
metabotropic: sweet, bitter, & umami

528
Q

what is the biochemical mechanism for tasting salty foods?

A
  • sodium channels open
  • allow influx of sodium depolarizaing the receptor cell
  • opens Ca2+ channels
  • increased intracellular Ca2+​ leads to neurotransmitter release
529
Q

what is the biochemical mechanism for tasting sour foods?

A

protons enter receptor cell

depolarize cell

opens voltage gated Ca2+ channels

increased intracellular Ca2+ causes release of neurotransmitter

530
Q

what is the biochemical mechanism for tasting sweet foods?

A

GCPR

close K+ leak channels

depolarization

neurotransmitter release

531
Q

SVA fibers for tast are carried by which cranial nerves and where do they synapse?

A
  • CN VII (anterior 2/3 of tongue & soft palate)
    • geniculate ganglion
  • CN IX (posterior 1/3 of tongue)
    • petrosal ganglion
  • CN X (epiglottis & oropharynx)
    • nodose ganglion
532
Q

which cranial nerves carry GSA fibers from the tongue?

A
  • CN V: anterior 2/3 of tongue & soft palate
  • CN IX: posterior 1/3 of tongue & tosilar fossa
  • CN X: epiglottis
533
Q

what axons for the solitary tract?

A

SVA fibers from geniculate, petrosal, and nodose ganglia

534
Q

what is the second order neuron of the gustatory pathway?

A

solitary nucleus in the medulla

535
Q

what is the 3rd order neuron of the gustatory pathway & how does the signal travel there from the 2nd order neuron?

A

VPM of the thalamus

via solitariothalamic tract

also signals with the hypothalamus & amygdala

536
Q

where does the gustatory signal travel from the VPM of the thalamus?

A

insula & frontal cortex

then to hypothalamus & amygdala

537
Q

where is the primary gustatory cortex?

A

insula

538
Q

factors that lead to decline in gustatory ability

A
  • age
  • head trauma
  • oral neoplasm
  • radiation
  • stroke
  • sx
  • tumor
539
Q

what are zietgebers?

A

“time givers”

environmental cues that modify circadian rhythm

540
Q

what inhibits melatonin production?

A

light exposure

541
Q

describe the neural pathway for light induced inhibition of melatonin.

A
  • environmental (blue) light is detected by retina
  • signal travels via retinohypothalamic tract to suprachiasmatic nucleus of teh hypothalamus
  • signal then travels to paraventricular nucleus (also hypothalamus)
  • paraventricular nucleus axons travel down to & synapse on preganglionic sympathetic neurons in spinal cord
  • signal that reascends to superior cervical ganglia
  • postsynaptic neurons synapse on pineal gland
542
Q

at what point in sleep-wake cycle is growth hormone highest?

A

early sleep

543
Q

at what point does melatonin peak in the sleep-wake cycle?

A

mid-sleep

approx. 3-4hrs in

544
Q

when are cortisol levels highest in the day?

A

just before waking

545
Q

what type of brain waves are seen in N1 non-REM sleep stage?

A

transition from alpha wave (awake, eyes closed) to theta waves (drowsy sleep)

546
Q

presentation of N1 stage of non-REM sleep

A

hypnic jerks

hypnagogic hallucinations

loss of some muscle tone

loss of most conscious awareness of external environment

547
Q

what type of brain waves characterize N2 stage of non-REM sleep?

A

sleep spindles & K complexes

548
Q

what is this?

A

a K complex

549
Q

what is this?

A

sleep spindle

550
Q

presentation of N2 stage of non-REM sleep

A

decreased muscular activity

no conscious awareness of external environment

teeth grinding may occur

551
Q

what percentage of sleep is spent in stage N2 non-REM sleep?

A

40-55%

552
Q

what type of brain waves are associated with N3 stage of non-REM sleep?

A

delta wave

slow brain waves

553
Q

parasomnias occur in what stage of sleep?

A

N3 non-REM

554
Q

what is REM sleep?

A

wakeful brain w/paralyzed body

beta waves

rapid low-voltage EEg

rapid eye movements (REM)

555
Q

when does dreaming occur?

A

REM sleep

556
Q

what percentage of sleep is spent in REM?

A

20-25%

557
Q

when do alpha waves occur?

A

awake

558
Q

how does sleep change throughout the night?

A

time spent in non-REM is shorter in duration & N3 disappears

cycles are shorter in duration

initatial cycle is 90’

559
Q

how does sleep change with age?

A

overal time becomes shorter

smaller percentage spent in REM: 50% in infants & 20% in adults

N3 (deep sleep) gets short and can even disappear completely in elderly

560
Q

what physiologic changes occur in REM sleep?

A

increases in HR & RR

penile erections

561
Q

why are people irritable when they are sleep deprived?

A

b/c sleep deprivation causes increase activation of the amygdala which is associated with rage

562
Q

how does sleep deprivation affect your health?

A
  • increased susceptibility to viral infections
  • weight gain
  • DM II
  • HTN
  • heart dz
  • mental illness
  • mortality
563
Q

what is a MEG?

A

magnetoencephalogram

records miniscule magnetic signal generated by neural activity

more detailed than an EEG, but we don’t understand enough to interpret differently

564
Q

requirements for dx of narcolepsy

A

3+ sleep attacks/week for 3+ months

plus one of: cataplexy, hypocretin deficiency, or rapid REM onset (<15’/normal 1hr)

565
Q

what neurotransmitter is low in insomniacs?

A

GABA

566
Q

when does sleepwalking occur?

A

aka somnambulism

non-REM

typically the first few hours of sleep

567
Q

what are the differences between night terrors & nightmares?

A

night terrors occur during non-REM, while nightmares are in REM

nightmares can be remembered upon arousal

568
Q

if night terrors aren’t remembers after arousal, then how do we know they occur?

A

presence of autonomic reaction after arousal

increased HR, pupillary dilation, sweating, goosebumps

569
Q

what sleep disorder affects blood oxygen levels?

A

sleep apnea at night only

sleep-related hypoventilation is sustained during wakefullness

570
Q

what are the types of sleep apnea and how are they differentiated?

A
  • central
    • effort to breath is diminshed or absent for 10-30”
  • obstructive
    • causes snoring
    • tongue or other part of airway closes down & obstructs oxygen delivery
571
Q

presentation of sleep-related hypoventilation

A
  • increased arterial pCO2 compared to waking
  • diaphragm weakness
  • morning headaches
  • may coexist with sleep apnea
  • associated w/COPD, obesity, & muscular dz
572
Q

what is commonly associated with restless leg syndrome?

A

Fe deficiency

573
Q

what is the driving force for trying to make up for lost sleep?

A

accumulation of substances in the brain during wakefulness

including adenosine

574
Q

when do low-voltage, fast brain waves occur?

A

waking

575
Q

how does the SCN integrate information about the body’s alertness?

A

it has melatonin receptors for positive feedback

and

serotonin from the Raphe nuclei about wakefulness

576
Q

how do different neurochemical levels change during sleep?

A

SANDman

  • Serotonin: helps initiate sleep, rises w/onset and falls w/waking
  • ACh: higher during REM sleep
  • NE: lower during REM
    • ratio of ACh:NE is a biological trigger for REM sleep
  • Dopamine: produces arousal & wakefulness, rises w/waking and falls w/sleep onset
577
Q

what are the main components of the basal ganglia?

A

striatum

lentiform nucleus

subthalamic nuclei

substania nigra pars compacta & pars reticularis

578
Q

what nuclei form the striatum?

A

caudate nucleus

putamen

nucleus accumbens

579
Q

what nuclei form the lentiform nucleus?

A

putamen

globus pallidus externa & interna

580
Q

what is the main function of the basal ganglia?

A

initiate movements & stop unwanted/unneeded movements

581
Q

any time there is a connection to the putamen, what other nucleus will also be activiated?

A

caudate

582
Q

what is the major output of the striatum?

A

inhibitory on globus pallidus & substantia nigra

583
Q

the subthalamic nucleus has excitatory action on?

A

globus pallidus externa

globus pallidua interna

substantia pars reticulata

**this is the only excitatory connection in the basal ganglia**

584
Q

what are the inputs to the subthalamic nucleus?

A

excitatory from the cortex

inhibitory from teh globus pallidus externa

585
Q

what type of output comes from the substantia nigra pars compacta?

A

modulatory w/widespread targets especially in the striatum

586
Q

what is the direct pathway thru the basal ganglia?

A

causes disinhibition of the thalamus→ excitation of the cortex

  • cortex excites striatum
  • striatum inhibits globus pallidus interna
  • globus pallidus interna stops inhibiting thalamus
  • thalamus excites cortex
587
Q

what is the indirect pathway thru the basal ganglia?

A

causes inhibition of thalamus→ little/no excitation to cortex

  • cortex excites striatum
  • striactum inhibits globus pallidus externa
  • globus pallidus externa stops inhibiting subthalamic nucleus
  • subthalamic nucleus excites substantia nigra pars reticulata
  • substantia pars reticulata inhibits thalamus
  • thalamus cannot excite cortex
588
Q

how does the substantia nigra pars compacta modulate the direct pathway?

A

excites the direct pathway→ overall net result of movement

589
Q

how does the substantia nigra pars compacta modulate the indirect pathway?

A

inhibits indirect pathway→ overall net result of movement

590
Q

hypokinetic disorder of the basal ganglia

A

Parkinson’s disease

591
Q

hyperkinetic disease of basal ganglia

A

Huntington’s disease

athetosis

hemiballismus

592
Q

clinical features of Parkinson’s dz

A
  • tremor (don’t understand why)
  • rigidity
  • bradykinesia
  • anteroflexed posture
  • postural instability
  • freezing/festinating gait
  • poor balance
593
Q

MOA of carbidopa

A

prevent breakdown of dopamine

594
Q

pharmaceutical tx for Parkinson’s

A
  • l-dopa
  • prevent breakdown of dopamine
  • D2 agonist (pretend to be dopamine)
  • selective MAO-B inhibitors
595
Q

clinical features of Huntington’s dz

A
  • chorea
  • gradually worsening dementia & personality changes
596
Q

regions of brain affected by Parkinson’s dz

A

substantia nigra pars compacta

597
Q

region of brain affected by Huntington’s dz

A

striatum: caudate nucleus

medium spiny neurons

598
Q

clinical features of athetosis

A

slow, writhing movements

more pronounced in hands & fingers

599
Q

region of brain affected by athetosis

A

lesions in striatum

600
Q

clinical features of hemiballismus

A

wild flailing movements of one arm or leg

601
Q

region of brain affected in hemiballismus

A

subthalamic nucleus

typically caused by stroke in small ganglionic branch of posterior cerebral artery

602
Q

what is nociceptive pain?

A
  • can be acute or chronic
  • proportionate to stimulation of the nociceptor
  • consistent w/degree of tissue injury
  • serves protective function
603
Q

why is acute pain good?

A
  • defense mechanism
  • protects form external harm
  • prevents further damage
  • prevents activity while healing

learning & response

604
Q

what causes congenital pain insensitivity?

A

autosomal recessive inheritance

605
Q

function of free nerve endings in sensation

A

pain & temperature

amount of myelination determines speed

606
Q

function of Meissner’s corpuscles

A

proprioception

dynamic deformation

607
Q

function of Pacinian corpuscles

A

vibration/deep pressure

rough v. smooth

608
Q

function of Ruffini’s corpuscles

A

stretch of skin & sustained pressure

modulation of grip

609
Q

function of Merkel’s disks

A

pressure

two point discrimination

610
Q

what sensory receptors have rapidly adapting mechanoreceptors?

A

Meissner’s & Pacinian corpuscles

611
Q

what sensory receptor has slowly adapting mechanoreceptors?

A

Merkel’s disks & Ruffini endings

612
Q

what type of axons confer proprioception?

A

Aalpha fibers

613
Q

what type of axons confer mechanoreception?

A

A-beta fibers

614
Q

what type of axons confer nociceptive information?

A

A-delta (fast) & C (slow= no myelin) type fibers

615
Q

what type of axons confer temperature?

A

cold is sent by A-delta fibers

hot by C fibers

616
Q

what type of axon fiber is associated with “Ow!”?

A

A-delta

fast pain fibers

initial sharp pang

617
Q

what type of axon fiber is associated with “aahhh”?

A

C fibers

slow pain reception

throbbing

618
Q

where do A-beta fibers synapse?

A

lamina V of the dorsal horn in the spinal cord

619
Q

where do C fibers synapse?

A

lamina II aka substantia gelatinosa of the dorsal horn of the spinal cord

620
Q

where do A-delta fibers synapse?

A

laminas I (posteromarginal nucleus) & V

dorsal horn of spinal cord

621
Q

why does message lessen pain?

A

Gate control theory

  • message activates stretch receptors
  • stretch receptors signal via A-beta fibers
  • A-beta fiber excite inhibitory interneuron w/in the spinal cord
  • inhibitory neuron suppresses ascending pain signal
622
Q

features of Tabes Dorsalis

A
  • impaired proprioception
  • locomotor ataxia
  • loss of tactile discrimination
  • loss of vibration sensation
  • loss of reflex
  • positive Romberg sign (fall over when they close their eyes)
623
Q

cause of tabes dorsalis

A

tertiary syphilis

624
Q

features of syringomyelia

A
  • bilateral loss of pain & temp @ level of lesion
    • due to lesion at ventral white commissure
  • flaccid paralysis: advanced disease
  • muscle atrophy
  • sensory dissociation
625
Q

cause of subacute combined degeneration

A

vitamin B12 deficiency→ demyelination/neuropathy

OR

Friedreich’s ataxia (autosomal recessive)

626
Q

features of subacute combined degeneration

A
  • loss of tactile discrimination
  • loss of vibratory sensation
  • impaired proprioception
  • spastic paresis/paralysis
    • Romberg’s sign
  • + Babinski’s sign
627
Q

features of anterior spinal artery occlusion in cervical region

A
  • loss of pain & temp
    • spinaothalamic tract
  • loss of motor→ spastic paraplegia
    • corticospinal tract
  • fascicluations (irregular muscle contractions
  • atrophy
  • bilateral
  • below occlusion
628
Q

features of spinal cord hemisection

A

aka Brown Sequard Syndrome

  • ipsilateral loss of all sensation at level of lesion
  • ipsilateral loss of touch, vibration, & proprioception below lesion
  • contralateral loss of pain & temp below lesion
  • flaccid paralysis at level of lesion
  • ipsilateral paresis below lesion
    • hyperreflexive
      • Babinski’s sign
629
Q

what causes trigeminal neuralgia?

A

pain initiated by movement of the mandible

caused by demyelination of V3 axon, often by pressure from aberrant artery

630
Q

how is trigeminal neuralgia treated?

A

carbamazepine (anticonvulsant)

or sx removal of aberrant artery causing issure

631
Q

cause of Brown-Sequard Syndrome

A

most commonly penetrating trauma

could also be: blunt trauma, disc herniation, or spinal tumor

632
Q

thalamic pain syndrome

A

chronic pain

caused by lesions or occlusion of blood vessels in posterior thalamus

initial lack of sensation & tingling in the body

weeks-months, numbness develops into severe chronic pain, not proportional to environmental stim.

633
Q

mesencephalic nucleus receives?

A

proprioception of the face

634
Q

principal sensory nucleus receives?

A

discriminative & light touch of face

conscious proprioception of the jaw

635
Q

spinal trigeminal nucleus receives?

A

deep/crude touch, pain, & temp from ipsilateral face

VII, IX, & X inputs too

636
Q

Brodmann’s area for Broca’s area

A

44, 45

637
Q

Brodmann’s area for Wernicke’s area

A

22

638
Q

how is auditory information organized within the auditory cortex?

A

tonotopically

just like on the basilar memebrane of the cochlea

639
Q

how is auditory information transmitted from the cochlea to the primary auditory cortex?

A
  • hair cells of basilar membrane
  • spiral ganglion
  • auditory nerve
  • cochlear nucleus
  • CN VIII vestibulocochlear nerve
  • auditory cortex
640
Q

what type of sound wave produce soft sounds?

A

low intensity

641
Q

what type of sound wave produce loud sounds?

A

high intensity

642
Q

what type of sound wave produce low pitched sounds?

A

low frequency

643
Q

what type of sound wave produce high pitched sounds?

A

high frequency

644
Q

what neural structure is responsible for sound localization?

A

superior olivary complex

645
Q

what is interaural time delay?

A

time difference for sound to reach each ear

typically for sounds in the 20-2000Hz range

646
Q

what is interaural intensity difference?

A

sound level difference between each ear

usually caused by sound shadowing effect of the head for high frequency sounds (2000-20000Hz)

647
Q

how is interaural time delayed used to localize sound?

A

axons from cochlear nuclei synapse on multiple neurons of medial superior olive (MSO)

where action potentials of both sides converge (coincident arrival) on an MSO neuron

648
Q

why does unilateral damage above the superior olivary nucleus not result in deafness?

A

bilateral innervation above the superior olivary nucleus

649
Q

what is the auditory pathway?

A

SLIM

  • Superior olivary nucleus
  • Lateral lemniscus
  • Inferior colliculus
  • medial geniculate nucleus of the thalamus
650
Q

what neural structure is responsible for analyzing quality of sound?

A

dorsal cochlear nucleus

651
Q

what neural structure is responsible for preserving timing of sound?

A

ventral cochlear nucleus

652
Q

conductive hearing loss is caused by?

A

a problem in the middle ear, either broken bone or dislocation

653
Q

how does the Rinne test work? interpret the results.

A
  • activate tuning fork
  • touch to mastoid bone (bone conduction)
  • when pt stops hearing sound, move fork to side of pinna (air conduction)→ should hear again
  • if AC>BC, normal hearing
  • if BC>AC, conductive hearing loss
654
Q

how does the Weber test work? interpret the results.

A

activate tuning fork & place on top of skull or forehead

  • if heard the same bilaterally→ normal hearing
  • if louder in affected ear→ conductive hearing loss
  • if louder in unaffected ear→ sensorineural hearing loss
655
Q

interpretation of left lateralization on Weber test & AC>BC by Rinne test of both ears?

A

right sensorineural hearing loss

656
Q

interpretation of right lateralization on Weber test & both ears BC>AC on Rinne test

A

right conductive hearing loss

left conductive & sensorineural hearing loss

657
Q

what information is received by the lateral superior olivary complex?

A

excitatory input from ipsilateral cochlear nucleus

inhibitory input from MNTB that was excited by contralateral cochlear nucleus

Neuroscience (2 decks)

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