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Neuro Soltesz
KYCOM Block 8
116
Anatomy
Graduate
05/17/2013

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Term
what is another name for lower motor neuron
Definition
final common pathway
Term
explain where and what upper motor neurons do
Definition
descending brain and spinal cord paths involved in voluntary skeletal muscle control
Term
what are the parts of the brain used for movement
Definition
cortex; motor area, prefrontal, association areas, parietal cortex

corpus atratium
thalamus
subthalamic nuclei
substantia niagra
reticular formation
vestibular nuclei
inferior olivary complex
cerebellum
Term
what are the types of neurons in the motor systems
Definition
alpha motor neurons to extrafusal fibers
gamma motor neurons to intrafusal fibers
Term
alpha motor neurons: size, what do they innervate
Definition
large fibers that innervate extrafusal fibers (the bulk of the muscle)
Term
define a motor unit
Definition
a motor neuron and all the fibers it innervates
Term
what are the characteristics of a type 1 a motor fiber
Definition
contracts slow
resistant to fatuge (not a lot of myofibrillar ATPase to fatuige)
Term
what are the characteristcs of a type 2 alpha motor fiber
Definition
fast contraction
repid fatigue (lots of myofibrillar ATPase)
can be divided into 2a and 2b
Term
gamma motor neuronL size, location, innervate, function
Definition
small

many nuclei in the middle not beneath the sarcolemma with no striations

gamma neurons innervate the intrafusal fibers on the muscle spindles (usually near tendon)

determines proprioception
Term
what are the three types of neurons that innervate a muscle spindle, where do they go, what synapse do they make, how do they function
Definition
o 1a fiber: loses myelin sheath as it pierces the capsule and wraps around intrafusal fiber forming the annulospiral ending / primary ending of the spindle
o 2 fiber: ends in varicosities on intrafusal muscle fibers away from the middle region (flower spray endings / secondary ending of the spindle)
o 1a and 2 Fibers act as mechanoreceptors: stretching opens ion channels in fiber to open and initiates AP
o Gamma motor neurons: innervate polar region of the intrafusal muscle
Term
explain the process of the myotactic stretch reflex
Definition
• Tapping tendon stimulates primary endings in muscle spindles (rapid stretch doesn’t do much to secondary endings)
• 1a fibers take impulse to the spinal cord and synapse with a motor neuron (monosynaptic) that supply extrafusal fibers in the muscle
• 1a fibers also synapse with inhibitor interneurons that inhibit a motor neurons and supply antagonist muscles
Term
what are the commonly tested muscles in the myotactic stretch reflex, what vertebral nerve do they correspond with
Definition
o Biceps: musculocutaneous nerve C5-C6
o Brachioradialis: radial nerve C6
o Triceps: radial nerve C7
o Patellar: femoral nerve L4
o Achilles: tibial nerve S1
Term
what is the function of the gamma loop, how does it work
Definition
• Maintains muscle tone
• Supraspinal activation of gamma motor neurons leads to muscle contraction in polar regions in intrafusal fibers stretching equatorial region of intrafusal muscle fibers
• Increase in fiber activity activates a motor neurons that cause muscle contraction
Term
what and where is a golgi tendon organ, what is the function
Definition
• Receptors in tendons close to the junction of muscle fibers
• Nerve fibers intertwined with collagen fibers of the tendon acting as mechanoreceptors
• Stretch causes ion channels to open
• Montiors tension
Term
how does the golgi tendon organ work
Definition
o GTO stimulated
o 1b fibers carry info to spinal cord (large diameter, myelinated, fast)
o 1b fiber synapses with inhibitior interneuron in the ventral horn
o Inhibit a motor neuron causing inverse myotatic reflex (autogenic inhibition)
Term
where does the corticospinal tract originate
Definition
comes from the primary motor area. There is some from premotor, supplementary, primary somatosensory, and parietal too.
Term
where do the fibers that came from the parietal lobe and enter the corticospinal tract go to and their function
Definition
o terminate at the base of the dorsal horn (laminae V and VI)
o regulation of afferent signals
Term
where do the fibers that come from the frontal lobe and enter the corticospinal tract go to
Definition
o terminate in ventral horn and intermediate zone (laminae VII, VIII, IX)
o some synapse with lower motor neurons but most with interneurons
Term
explain the general course of the corticospinal tract until it splits into two options
Definition
• corona radiate > posterior limb of internal capsule > middle third of crus cerebri > basilar pons > medullary pyramid >
Term
after the corticospinal tract gets to the medulla what happens
Definition
o most decussate in medulla > lateral funiculus lateral corticospinal tract
o no decussation > anterior funiculus anterior corticospinal tract > decussate at level of termination
Term
where does the corticonuclear tract oroginate, what path does it take
Definition
 Originates from precentral gyris (face area of primary motor area)
 Corona radiate > genu of internal capsule > middle third o cerebral crus > basilar pons > medullary pyramid > brainstem > gets thinner as it contributes to cranial nerves ipsilaterally and contralaterally
Term
what CN nuclei does the corticonuclear tract contribute to is it contralateral, bilateral, or ipsilateral
Definition
• Trigeminal motor nucleus
• Facial nucleus: Lower motor neurons in the facial nucleus innervate muscles of lower face are only supplied by contralateral corticonuclear tract.
• Hypoglossal nucleus: Contribution to the geniglossus is mostly from contralateral corticonuclear tract
• Accessory nucleus: Fibers from ipsilateral corticonuclear tract are recieved
• Nucleus ambiguous: Soft palate is contribution is mostly from contralateral corticonuclear tracts
Term
primary motor cortex: location, organization, stimulation, function, lesion
Definition
o Precentral gyris and anterior paracentral lobule
o Somatotopic representation of body upside down (like homonuculus in sensory)
o Stimulation: constriction of discrete muscle groups or muscles contralateral
o Function: voluntary skilled movements
o Lesion: weakness of contralateral body parts
Term
premotor and supplementary motor cortex: location, stimulation, organization, function, lesion
Definition
o Anterior to the primary motor cortex
o Stimulation: large complex muscle group movements
o Less precise somatotopic representation
o Function: preparation and programming movement
o Lesion: apraxia (can’t perform learned motor skill)
Term
what is the blood supply to the cortical motor areas, what does each supply specificially
Definition
o Middle cerebral artery: face and upper limb areas
o Anterior cerebral artery: lower limb
Term
what happens if you occlude blood in each of the supplies to the cortical motor areas
Definition
Occlusion MCA: paralysis and weakness of contralateral lower face and upper limb

Occlusion ACA: paralysis and weakness of opposite lower limb
Term
what are the brainstem spinal systems that create voluntary movement
Definition
medial and lateral vestibulospinal tract
medial and lateral reticulospinal tract
rubrospinal tract
Term
medial vestibulospinal: location, function
Definition
Descends as MLF

Controls neck muscles
Term
lateral vestibulospinal: location, function
Definition
Through length of cord

Control posture and balance
Term
what activates the reticulospinal system, what does it do and how
Definition
o Activated by ipsilateral corticocrticular fibers and ascending spinoreticular fibers (mostly nocioceptive)
o Maintaim posture and muscle tone via gamma motor neuron influence
Term
medial reticulospinal: AKA, explain the pathway and function
Definition
pontine

Comes from pontine reticular formation

Descends ipsilateral in anterior funiculus at all cord levels

Synapses with interneurons at laminae VII and VIII

Excites extensors
Term
lateral reticulospinal: AKA, pathway, function
Definition
medullary

Comes from medullary reticular formation

Descends bilaterally (crossed and uncrossed) in lateral funiculus at all cord levels

Synapses with laminae VII and VIII

Inhibits extensors
Term
rubrospinal tract: origin, pathway, function
Definition
o Afferent fibers from cerebral cortex and cerebellum >
o Red nuclei in midbrain tegmentum at level of superior colliculi >
o Rubrospinal tract > decussation in midbrain (ventral tegmental decussation) >
o A few fibers extend to the cervical enlargement
o Upper limb motor neurons excite flexors
Term
upper motor neuron lesion: location, effect
Definition
o Located in CNS
o Never affect individual muscles
o Affect groups supplied by motor nuclei below the level of the lesion
Term
lower motor neuron lesion: location, effect
Definition
o Located in the PNS or CNS
o Only muscles innervated by the damaged neuron are affected
Term
decebrate posturing (rigidity) definition
Definition
o Activity or inactivity of the brainstem can be indicators in comatose
Term
what can a lesion in upper midbrain and pons (supratentorial extending through notch) effecting the red nuclei do
Definition
can cause decerebrate posturing of red nucleus

Upper and lower limbs extend when comatose patient receives stimuli

Mediated by reticulospinal and vestibulospinal
Term
what can a lesion above the red nuclei (supratentorial) do
Definition
 Lower limbs extend, upper limbs flex when comatose patient receives stimuli
Term
in decebrate posturing (rigidity), explain the different progosis possible and the reasons for them
Definition
o Decerebrate to decorticate: Brainstem impairment is receding from caudal to rostral direction. Better prognosis
o Decorticate to decerebrate: Impairment is proceeding from rostral to caudal direction and may become life threatening. Poor prognosis
Term
what is the final common pathway
Definition
lower motor neurons
Term
what are the areas of the brain used for motor movement
Definition
cerebral cortex (motor, prefrontal, association areas of parietal)
corpus striatum, thalamus, subthalamic nuclei, substantia niagra, reticular formation, vestibular nuclei, inferior olivary complex, cerebelum
Term
alpha motor neuron: what does it innervate, size, organization
Definition
large diameter
innervates extrafusal fibers
motur unit: alpha motor neuron and the fibers it innervates
Term
what are the types of extrafusal fibers, what are the differences
Definition
1. contract slow, fatigue resistant (little myofibrillar ATPase)

2. fast contraction, fatigue rapid (lots of myofibrillar ATPase)(2A and 2B)
Term
gamma motor neurons: describe the cell / fiber, general function, what does it innervate and where
Definition
small, manu nuclei in middle not beneath sarcolemme without striations

determines proprioception

innervate intrafusal fibers on muscle spindle in polar region of the muscle near tendon
Term
what are the sensory fibers of the muscle spindle: function, location, names
Definition
1a fiber: looses myelin as it pierces capsule, wraps around intrafusal fiber, forms annulospiral or primary ending of the spindle

2 fiber: ends in varicosities on intrafusal muscle fibers away from middle region making flower spray or secondary endings

both are mechanoreceptors, ion channels open with stretch
Term
explain the myotactic stretch reflex
Definition
tap tendon makes rapid stretch > 1a fiber sends impulse to cord > motor neurons synapse > contract extrafusal muscle

1a fiber > inhibitor interneiron > inhibit antagonist muscle
Term
what are the commonly tested reflexes, what nerve and vertebral nerve do they match with
Definition
biceps: MCN C5-6
brachioradialis: radial C6
triceps: radial C7
patellar: femoral L4
achilles: tibial S1
Term
explain the gamma loop: function, pathway
Definition
maintains muscle tone

supraspinal activation of gamma motor neuron > muscle contract in polar regions in intrafusal fibers > stretch in equatorial region of muscle > increase in fiber activity activates motor neurons that cause contraction
Term
golgi tendon organ: location, function, set up
Definition
receptors on tendons close with junction of muscle fibers
nerve fibers intertwin with collagen fibers of the tendon acting as mechanoreceptors
stretch causes ion channels to open

monitors tension
Term
explain the pathway of the golgi tendon organ
Definition
once the GTO is stimulated > 1b fibers > spinal cord > inhibitor interneuron in ventral horn > inhibit motor neuron of myotactic reflex (autogenic inhibition)
Term
cortical spinal tract origin
Definition
primary motor area mostly

premotor, supplementary motor, primary somatosensory, parietal
Term
where do corticalspinal fibers from the parietal lobe go to and function
Definition
terminate at base of dorsal horn laminae V and VII

regulate afferent signals
Term
where do cortical spinal fibers from the frontal love go to
Definition
terminate in ventral horn and intermediate zone laminae VII, VIII, IX

some synapse with lower motor neurons, most with interneurons
Term
describe the course of the corticospinal tract
Definition
corona radiata > posterior internal capsule > crus cerebri > basilar pons > medullary pyramid >...

decussate in medulla > lateral corticospinal tract

OR

anteior corticospinal tract > decussate at level of termination
Term
what is the pathway of the corticonuclear tract
Definition
precentral gyrus (face area of primary motor cortex) > corona radiata > genu internal capsule > crus cerebri > basilar pons > medullary pyramid > contributes to cranial nerves
Term
what CN does the corticonuclear tract contribute to: indicate ipsilateral, bilateral, contralateral
Definition
trigeminal motor nuclei

facial nucleus: upper face is bilateral, lower face is contralateral

hypoglossal nuclei: genioglossus contribution is contralateral

accessory nuclei: only recieves ipsilateral

nucleus ambigous: soft palate is contralateral
Term
primary motor cortex: location, organization, stimulation, function, lesion
Definition
precentral gyrus and anterior paracentral lobule

somatotopic inversed like homonuclus

stimulate: constrict discerte muscle groups contralateral

lesion: weak contralaterally
Term
premotor corted and supplementary motor area: location, stimulate, organization, function, lesion
Definition
anterior to primary motor cotex, premotor is lateral

stimulate: large complex muscle group movement

less percise but still somatotopic

preperation and performing movement

lesion: apraxia (cant perform learned motor skill)
Term
blood supply to the motor cortices
Definition
middle cerebral artery: face and upper limbs

anterior cerebral artery: lower limb
Term
middle cerebral and anterior cerebral artery occlusion
Definition
middle: paralysis of contralateral lower face and upper limb

anterior: paralysis of opposite low limb
Term
vestibulospinal tracts: location, function
Definition
medial: descends as MLF, control neck muscle
lateral: through length of cord, control posture and balance
Term
reticulospinal input and function
Definition
ipsilateral corticonuclear and ascending spinoreticular nocioceptive

maintain posuture and muscle tone via gamma motor neurons
Term
medial / pontine reticulospinal pathway
Definition
pontine reticular formation > bilateral descends > synapse laminae VII, VIII > excite extensors
Term
lateral / medullary reticulospinal pathway
Definition
medullary reticular formation > bilateral descends > synapse laminae VII, VIII > inhibit extensors
Term
rubrospinal: pathway, function
Definition
afferent from cerebral cortex and cerebrllum > red nuclei > rubrospinal tract > decussate midbrain > cervical enlargement > up limb excite flexors
Term
upper motor neuron lesion: location, effect
Definition
in cns
effects groups supplied by motor nuclei below lesion
Term
lower motor neuron lesion
Definition
PNS or CnS
affects only muscle innervated
Term
decerebrate definition
Definition
damage to upper brainstem (lesion in upper midbrain or midpons or lesion above red nuclei)
Term
decrtidate definition
Definition
damage to cortico spinal tract(s)

patient has arms curled up
Term
in rigid posturing, what progression is bad
Definition
decordidate to decerebrate: damage is moving into medulla and brain
Term
describe a lesion in the upper midbrain or mid pons that causes decerbrate posturing
Definition
supratentorial: through notch

red nuclei damage: causes posture

stimulation leads to lower and upper limb extension

mediated by reticulospinal and vestibulospinal ract
Term
describe diagnosis of a lesion above the red nuclei (supratentorial) that causes decrebrate rigidity
Definition
low limbs extend, upper limbs flex when comotose recieves stimuli
Term
what are the basal ganglia according to the non-clinical definition
Definition
clastrum, amygdaloid body, corpus striatum
Term
non-clinical corpus striatum: location, parts, subparts
Definition
gray matter at base of cerebral hemispheres

caudate nuclei, lentiform nuclei (putamen and globus pallidus / pallidum)
Term
striatum: apperance, composition, main function
Definition
striated apperance

caudate nucleus, putamen, nucleus accumbens

area of the corpus striatum that recieves the most afferent fibers
Term
corpus striatum clinical definition
Definition
lentiform: putamen, globus pallidus / pallidum
caudate nuclei
nucleus accumbens
Term
basal nuclei clinical definition
Definition
lentiform (putamen, globus pallidus), caudate, nucleus accumbens, subthalamic nuclei, substantia nigra
Term
negative motor sign: signs, examples
Definition
patient wants to perform but cant, difficulty making motor neurons fire, no paresis or paralysis

seen in parkinsons disease

skinesia/hypokinesia: cannot initiate voluntarly movement

bradykinesia: reduction in veolcity and amplitude of movement
Term
positive motor sign: signs, examples
Definition
patient does not want to perform but cant stop, motor neurons are firing when they shouldnt

hyperkinesia, tremor, chorea, athetosis, ballismus
Term
tremor
Definition
rhythmic or oscillatory movement of distal limbs
Term
chorea
Definition
rapid jerk of distal limbs, face, or tongue
Term
athetosis
Definition
slow eithering, snake like movements
Term
ballisums/ballis,: define, usual cause
Definition
violent firing of entire limb (usually due to subthalamic nuclei lesion)
Term
what does dopamine normally do
Definition
excite striatal neurons via D1 and inhibit via D2

facilitate direct and inhibit indirect pathways

net decrease in cortical output
Term
what is the process in parkinsons disease
Definition
decreased activity of direct pathway and increased indirect

increased activity of medial globus pallidus causes thalamic inhibition and decreased cortical output
Term
parkinsons disease signs
Definition
cogwheel digidity of muscles

poverty of movement: slow tremor

bradykinesia

fenstination

loss of melanin in neurons of pars compacta of substantia niagra
Term
bradykinesia
Definition
mark like face, difficultly initiating movement, loss of associated movement like swinging of arms
Term
festination
Definition
shuffle gait that is slow and picks up speed with tendency to fall forward an inability to stop
Term
hyperkinesia cause, define
Definition
involuntary movement due to decreased activity in subthalamic nuclei via direct damage (hemiballismus) or damage to striatal neurons (huntingtons)

medial globus pallidus causes less inhibition of thalamus

connection between thalamus and motor cortex are hyperactive increasing cortical output
Term
huntingtons disease; MOA, cause, symptoms
Definition
dominant inheritance

atrophy of striatum inc aidate nuclei

choreiform movement that gets severe with time, athetosis, progressive mental detoriation
Term
ultametly what does the direct and indirect pathway do
Definition
inhibit (or not) the thalamus which stimulates the cerebral cortex via glutamate which stimulates motor neurons
Term
what is the point of the direct pathway
Definition
initiate involuntary movement
Term
what is the point of the indirect pathway
Definition
prevent unwanted contractions from competing with voluntary movement
Term
through what common pathway is the direct and indirect pathway initiated
Definition
stimulation of the cerebral cortex via tha thalamus causes the cortex to stimulate the striatum via glutamate which begins either pathway
Term
explain the direct pathway
Definition
from the stimulated striatum:striatalpallidal or strianigral fibers use GABA or substance P to inhibit the globus pallidus medial and the substantia niagra reticulata.

this inhibits thalamic dishinibition so the thalamus is able to continue exciting the cerebral cortex and motor fibers still function
Term
explain the indirect pathway (without the subthalamic nucleus)
Definition
from the stimulated striatum:striatalpallidal fibers inhibit the globus pallidus lateral with GABA and enkephalin

this stops the inhibition the globus pallidus lateral was doing on the globus pallidus medial and substantia nigra reticulata

this allows the continued inhibition of the thalamus by the fibers of the globus pallidus medial and substantia nigra reticulata which will stop the stimulation of the cortex and motor fiber activity
Term
explain the addition of the subthalamic nuclei onto the indirect pathway (subthalamic nuclei disinhibition)
Definition
striatum turns off the globus pallidus lateral

this allows the subthalamic nuclei to keep working. it stimulates the globus pallidus medial and substantia nigra with glutamate so they can continue to inhibit the thalamus so less motor activity is produced
Term
what is the subthalamic fasiculus
Definition
pallidosubthalamic and subthalamopallidal fibers that connect the globus pallidus and subthalamic nuclei
Term
explain how the globus pallidus medial and the substantia nigra are connected to the thalamus for thalamic disinhibition
Definition
1. connected directly and use GABA and substance P to inhibit the thalamus

2. can travel down ansa lenticularis or lenticular fasiculus which join to make the thalamic fasiculus which inhibit the thalamus via GABA or substance P

both go to the VA, VL, and centromedian thalamic nuclei
Term
why do we care about the lenticular fasiculus and the ansa lenticularis if they both join anyways
Definition
lenticular fasiculus pass through posterior limb of the internal capsule

ansa lenticularis loops around posterior limb of the internal capsule
Term
explain how the substantia nigra compacta regulates
Definition
with D1 receptors it uses dopamine to stimulate the fibers of the direct pathway (striatalpallidal and sirianigral) which turns off inhibition allowing motor neuron activity

with D2 receptors it uses dopamine to inhibit the striatalpallidal fibers of the indirect pathway. this allows inhibition of the thalamus and decreases motor activity
Term
what is the phylogenetically oldest basal nuclei, what is its additional part
Definition
the globus pallidus

includes the paleostratium (pallidum)
Term
what recieves the most fibers from the corpus striatum
Definition
medial/internal globus pallidus
Term
subthalamic nuclei: shape, location
Definition
lens shaped

part of diencephalon: inferior to thalamus, posterior to hypothalamus, medial to internal capsule
Term
substantia nigra: location, parts, describe parts
Definition
at all midbrain levels, separating tegmentum from cerebral crus

pars compacta: dense cell rich with menalin, neurotransmitter is dopamine

pars reticulata: cell poor, dense fibers, GABAergic neurons, connections similar to medial globus pallidus
Term
substantia nigra lesion symptoms
Definition
akinesia (poverty of movement), rigidity, dyskinesia (purposeless involuntary movement)
Term
sydnehams chorea: AKA, cause
Definition
“St. Vitus’ Dance”
o Hemolytic streoptoccci infection, Emboli in corpus striatum
Term
wilson's disease: AKA, causes
Definition
"hepatolenticular degeneration”

o Genetic error in copper metabolism
o Degeneration in putamen and progression to cause cavitation of entire lentiform nuclei
o Cellular degeneration in cortex, red nuclei, and thalamus
Term
wilsons' disease presentation
Definition
o Appears between 10-25 YO
o Muscle rididity
o Dystonia
o Tremor
o Impairment of voluntary movement (including speech)
o Loss of facial expression
o Chirosis of the liver
Term
wilsons disease treatment
Definition
o Drugs that enhance urinary excretion of copper
Term
tardive dyskinesia cause
Definition
o Antipsychotic drugs antagonize dopamine cause parkinsonism

For schizophrenia (butyrophenones, haloperidol)
Term
tardive dyskinesia presentation
Definition
o Long term treatment can cause tardive dyskinesia: choreiform movement of the lips and tongue
o often persists after drug is withdrawn
Term
akinetic mutism causes
Definition
o bilateral cortical lesion in supplementary motor and cingulate areas so movement cannot be initiated
OR
o destruction lesion in upper pons
Term
akinetic mutism presentation
Definition
o asleep with relaxed muscles
o eyes with open in response to loud noise and will follow moving objects
Term
locked in syndrome: cause
Definition
o midpontine infarction that transects motor tracts
Term
mid pontine syndrome presentation: what things are and are not spared
Definition
o paralysis of all voluntary movements except eye movement because MLF is spared
o special sensory pathways and reticular formation spared
o conscious and can communicate only with eye movements
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