MOTOR PARALYSIS Flashcards
Reason behind muscle irritability
the axon is unstable and capable of spontaneous
impulse generation, and all the muscle fibers that it controls
may discharge sporadically; in isolation from other
units.
____________appears in the EMG as a large spontaneous
muscle action potential
Fasciculation
spontaneous contractions of multiple motor units cause
a rippling of muscle
Myokimia
The _____ and ______ set the pattern and timing of the
muscle action in any projected motor performance.
basal ganglia
cerebellum
Suprasegmental control
of the axial and proximal limb musculature (antigravity
postural mechanisms) is mediated primarily by the
________ and ________
reticulospinal and vestibulospinal tracts
A tap on a tendon stretches or perhaps causes vibration
of the spindle and activates its _____________.
Afferent projections from these fibers synapse directly
with ________ in the same and adjacent
spinal segments; these neurons, in turn, send impulses
to the skeletal muscle fibers, resulting in the familiar
_____________ or monophasic
nuclear bag fibers
alpha motor neurons
monosynaptic muscle contraction
The _________ are simultaneously inhibited
but through disynaptic rather than monosynaptic
connections.
alpha
neurons of antagonist muscles
_________ also
participate by providing negative feedback through
inhibitory synapses of alpha motor neurons (recurren t
inhibition)
Renshaw cells
___________
are silent in relaxed muscle and during passive stretch;
they serve, together with muscle spindles, to monitor or
calibrate the length and force of muscle contraction under
different conditions
Golgi tendon receptors
The alpha motor neurons of the_______ of the
anterior horn supply trunk or axial muscles, and neurons
of the ______supply the appendicular muscles
medial parts
lateral parts
The large neurons of the anterior horns of the spinal cord contain high concentrations of _________ as
their transmitter at the neuromuscular junction
choline acetyltransferase and use acetylcholine
The main
neurotransmitters of the descending corticospinal tract,
in so far as can be determined in humans, are ____
and _______
aspartate
glutamate.
_______ is the neurotransmitter released
by Renshaw cells, which are responsible for recurrent
inhibition, and by interneurons that mediate reciprocal
inhibition during reflex action.
Glycine
_______ serves as the inhibitory neurotransmitter
of interneurons in the posterior horn.
Gamma-aminobutyric
acid (GABA)
________ are released by primary afferent terminals
and interneurons and act specifically on excitatory amino
acid receptors.
L-glutamate and
L-aspartate
In LMN lesions,
The denervated muscle undergoes extreme atrophy,
being reduced to _________of its original bulk
within _________
20 or 30 percent
3 to 4 months.
This is caused by the interruption
of descending tonic excitatory impulses, which normally
maintain a sufficient level of excitation in spinal motor
neurons to permit the peripheral activation of segmental
reflexes.
spinal shock
what attenuates spinal shock
naloxone
This is
the only direct long-fiber connection between the cerebral
cortex and the spinal cord
CST
Indirect pathways
rubrospinal, reticulospinal, vestibulospinal, and
tectospinal
______percent of the descending axons arose in
the parietal lobe, _______ percent in motor area 4, and the remaining _____percent in premotor area 6
40
31
29
About ______ of the
fibers cross and the remaining fibers descend ipsilaterally,
mostly in the uncrossed ventral corticospinal tract
75 to 80 percent
_______in the corticospinal
tract account for mirror movements that are seen during
efforts at fine motor tasks, particularly in children,
Uncrossed fibers
Beyond their decussation, the corticospinal pathways
descend as well-defined bundles in the ___________ of the spinal cord
anterior and
posterolateral columns of white matter (funiculi)
The l___________ tract lies at the periphery of the cord, where it occupies
the most anterolateral portion of the anterior funiculus
ateral vestibulospinal
_________ is also electrically excitable
but requires more intense stimuli than area 4 to evoke
movements
Area 6, the premotor area,
Stimulation of the _________ elicits more general movement patterns, predominantly of proximal limb musculature.
rostral premotor area (area 6a)
Stimulation of this area
may induce relatively gross ipsilateral or contralateral
movements, bilateral tonic contractions of the limbs,
contraversive movements of the head and eyes with
tonic contraction of the contralateral arm, and sometimes
inhibition of voluntary motor activity and vocal arrest
SMA
The corticospinal and corticobulbar
tracts, which project to all levels of the spinal cord and
brainstem, terminating diffusely throughout the _______ and _________
nucleus
proprius of the dorsal hom and the intermediate zone
A _______, which arises
in the tectum (tectospinal tract), vestibular nuclei (vestibulospinal tract), and pontine and medullary reticular cells (reticulospinal tract) and terminates principally on the internuncial cells of the ventromedial part of the spinal
gray matter.
ventromedial pathway
function of the VM pathway
This system is mainly concerned with axial
movements-the maintenance of posture, integrated
movements of body and limbs, and total limb movements.
(
from
the magnocellular part of the red nucleus and terminates in the dorsal and lateral parts of the internuncial zone
A lateral pathway
function of the lateral pathway
This pathway adds to the capacity for independent use
of the extremities, especially of the hands
their fibers are
arranged somatotopically and influence stretch reflexes
corticoreticulospinal pathways
results of UMN lesion
decreased voluntary drive on spinal motor neurons
(fewer motor units are recruitable and their firing rates
are slower), resulting in a slowness of movement
increased degree of co-contraction of antagonistic
muscles, reflected in a decreased rate of rapid alternating
movements
activation of paralyzed
muscles as parts of certain automatisms called __________
(synkinesias).
If the upper motor neurons are interrupted above
the level of the facial nucleus in the pons, hand and arm
muscles are affected __________and the leg muscles to a ________
most severely
lesser extent
it is referred
to as “Broadbent’s law.”
distribution of facial paralysis
that relatively spares the forehead muscles,
fibers that descend to the upper medulla and then ascend recurrently to the pons
Pick’s bundle
the selective blocking of _________neurons abolishes spasticity as well as hyperactive segmental tendon reflexes but to leave power unchanged.
small gamma
___________ phenomenon-the result
of interruption of descending inhibitory pathways
release
the medial
reticulospinal and vestibulospinal tracts, which together
_________
facilitate extensor tone.
the_____________, which has
inhibitory effects on stretch reflexes
dorsal reticulospinal tract
primary involvement of
the _________ and thalamus
is the feature that determines the persistence of flaccidity
after stroke
lenticular nucleus of the basal ganglia
the hip, thigh and ankle
flex (dorsiflex) slowly, following an appropriate stimulus
Triple flexion response
a series of rhythmic involuntary
muscular contractions occurring at a frequency of
5 to 7 Hz in response to an abruptly applied and sustained
stretch stimulus. It
clonus
result of the propagation of a vibration wave from bone
to muscle, stimulating the excitable muscle spindles in its
path
Spread, or radiation of reflexes,
Baclofen, a derivative of GABA, as well as ________ and
_______ are thought to act by reducing the release of
excitatory transmitters from the presynaptic terminals of
primary afferent terminals
diazepam
progabide,
attentive patient loses the ability to execute previously
learned activities in the absence of weakness, ataxia,
sensory loss, or extrapyramidal derangement that would
be adequate to explain the deficit
apraxia
Lesions of the _______have the effect
of reducing the impulse to think, speak, and act
frontal lobes
if this part of the brain is damaged, complex patterns of
movement cannot be activated at all or the movements
are awkward and inappropriate.
parietal lobe
The failure to conceive or formulate an action to command, was referred to by Liepmann as ________.
_______in the dominant parietal lobe, the
_____________of both cerebral
hemispheres and their integral connections are involved
collectively to accomplish these actions
ideational apraxia.
Sensory areas 5 and 7
supplementary and premotor cortices
________ has been said to be characterized by difficulty
in “what to do,” whereas _______ is a block
in “how to do” as a result of an inability to transmit the
gesture to executive motor centers.
ideational apraxia
ideomotor apraxia
It is an illdefined
clumsiness and maladroitness that is the result
of an inability to fluidly connect or to isolate individual
movements of the hand and arm
limb-kinetic apraxia
paralysis that obscures the apraxia on one side
but causes a breakdown of fine finger movements on the
opposite side.
“sympathetic
apraxia”
the lesion responsible for ideomotor
apraxia, which affects both hands, usually resides in the
__________
left parietal region.
the most commonly
observed of all apraxias in practice.
It may occur with
lesions that undercut the left supramarginalgyrus or
the left motor association cortex and
oral-buccallingual apraxia,
dressing apraxia and constructional
apraxia are used to describe special manifestations
of _________
nondominant parietal lobe disease
where is the lesion?
there frequently
appears to be a conflict between the actions of
the hands, the normal one sometimes even restraining the
alien one.
corpus callosum
Damage in the __________
from any cause, as well as from the degenerative disease
called _________ are associated with a similar alien
hand syndrome.
left supplementary motor area
corticobasal ganglionic degeneration
It is associated with extensive
bilateral frontal lobe damage and has been likened,
unsatisfactorily in our view, to a bilateral alien hand
phenomenon
utilization behavior
In disuse atrophy, the tendon reflexes are _______
and nerve conduction studies are normal
retained
The
striatum, mainly the _______, is the receptive part of
the basal ganglia
putamen
the output nuclei of the basal ganglia
consist of the _______ and the___________ of the substantia
nigra
medial (internal) pallidum
pars
reticulata (nonpigmented portion)
Main efferent projections from the putamen
direct and indirect
a _________ efferent system from the
putamen to the medial (internal) pallidum then to the substantia nigra, particularly to the pars reticulata
direct
an indirect system originating in the putamen that
traverses the lateral (external) pallidum and continues to
the _________, with which it has strong reciprocal
connections.
subthalamic nucleus
the _____and l________ operate as a single functional unit, (at least in
terms of the effects of lesions in those locations on parkinsonian
symptoms and the neurotransmitters involved
subthalamic nucleus
lateral
pallidum
Within the ___________
an internal loop is created by projections from the
subthalamic nucleus to the medial segment of the pallidum and pars reticulata.
A second offshoot of the indirect
pathway consists of projections from the _____
to the __________output nuclei.
indirect pathway,
lateral pallidum
medial pallidonigral
From the internal pallidum, two bundles of fibers
reach the thalamus- the _______
ansa lenticularis and the fasciculus
lenticularis
The direct
striatomedial pallidonigral pathway is activated by ___________
projections from the sensorimotor cortex and by
______ nigral (pars compacta)-striatal projections
glutaminergic
dopaminergic
Activation of this direct pathway inhibits the __________which, in turn, disinhibits the _______ and __________ of the thalamus.
As a consequence, thalamocortical drive is enhanced and cortically initiated movements are facilitated.
medial pallidum,
ventrolateral , ventroanterior nuclei
The indirect circuit arises from
putamina! neurons that contain ________ and smaller amounts of _______
These striatal projections have an inhibitory effect on the lateral pallidum, which, in turn, disinhibits the subthalamic
nucleus through GABA release, providing subthalamic
drive to the medial pallidum and substantia nigra pars
reticulata.
gamma-aminobutyric acid (GABA)
enkephalin
enhanced conduction
through the indirect pathway leads to _______
by increasing _________,
whereas enhanced conduction through the direct pathway results in hyperkinesia by reducing pallidothalamic inhibition
hypokinesia, pallidothalamic inhibition
The toxin binds with high affinity
to monoamine oxidase (MAO), an extraneural enzyme
that transforms it to pyridinium, a toxic metabolite that
is bound by melanin in the dopaminergic nigral neurons
in sufficient quantities to destroy the cells, probably by
interfering with mitochondrial function.
1 -methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP)
________could produce extrapyramidal
syndromes
reserpine
and the phenothiazines,
________is the neurotransmitter of the excitatory
projections from the cortex to the striatum and of
the excitatory neurons of the subthalamic nucleus
Glutamate
The highest concentration of ACh, as
well as of the enzymes necessary for its synthesis and
degradation (choline acetyl transferase and acetylcholinesterase),
is in the _______
striatum.
Of the catecholamines, _______has the most
pervasive role but its influence can be excitatory or inhibitory depending on the site of action and the subtype of
dopamine receptor
dopamine
The Dl and D2 receptors are highly
concentrated in the _______ and are the ones most often implicated in diseases of the basal ganglia;
D3 in tHe ________,
D4 in the _________and certam
limbic structures,
and D5 in the _______
striatum
nucleus accumbens
frontal cortex
hippocampus.
In the striatum, the effects of dopamine act as a class of “Dl-like” (________) and “D2-like” (_________) receptors
Dl and D5 subtypes
D2, D3, and D4 subtypes
excittory Dl receptors predominate on the _________ neurons that are the origin of the direct striatopallidal output pathway,
whereas D2 receptors mediate the inhibitory
influence of dopamine on the _______
small spiny putaminal
indirect striatopallidal output,
drug-induced parkinsonian
syndromes and tardive dyskinesias (described
further on) are prone to occur when drugs are administered that competitively bind to the ________
but that the newer antipsychosis drugs, which produce fewer of these effects, have a stronger affinity for the ________
D2 receptor,
D4 receptor
___________, for example, depletes the striatum and other parts of the brain of dopamine;
____________ and __________
work by a different mechanism, probably by blocking
dopamine receptors within the striatum
Reserpine
haloperidol and the phenothiazines
drugs that
inhibit _____________ another
enzyme that metabolizes dopamine, prolong the effects of
administered L-dopa.
catechol 0-methyltransferase (COMT),
administration of ____________
restores the ratio between dopamine and ACh, with the
new equilibrium being set at a lower-than-normal level
because the striatal levels of dopamine are low to begin
with.
anticholinergic drugs
the excessive movements and
rigidity characteristic of the disease to a loss of nerve
cells in the striatum.
HD
A gentle push
on the patient’s sternum or a tug on the shoulders may
cause a fall or start a series of small corrective steps that
the patient cannot control and is called__________
(festination)
refers to involuntary arrhythmic movements of a forcible,
rapid, jerky type.
Although the movements are purposeless, the patient may incorporate them into a deliberate act, as if to make them less
noticeable.
chorea
A choreic movement may be superimposed
on the reflex movement, checking it in flight, so to
speak, and giving rise to the__________ reflex
“hung-up”
Chorea
differs from myoclonus mainly with respect to the ______
of the movements; the myoclonic jerk is much faster
speed
The chronic administration of _____________ (or an idiosyncratic reaction to these
drugs) is a common cause of extrapyramidal movement
disorders of all types, including chorea; these may
become manifest during use of the drug or in a delayed
“tardive” fashion
phenothiazine drugs
or haloperidol
The use of ________ or other anticonvulsant drugs
may cause chorea in sensitive individuals.
phenytoin
Chorea may be limited to one side of the body (hemichorea).
When the involuntary movements involve proximal
limb muscles and are of wide range and flinging in
nature, the condition is called __________
hemiballismus
In Huntington chorea, there are
obvious lesions in the ______ and ______
caudate nucleus and putamen
The condition is characterized by an
inability to sustain the fingers and toes, tongue, or any
other part of the body in one position
athethosis
In ATHETOSIS, As a rule, the abnormal movements are
most pronounced in the digits and hands, face, tongue,
and throat, but no ________
group of muscles is spared
Athetosis may affect all four limbs or may be unilateral,
especially in children who have suffered a hemiplegia
at some previous time _________
(posthemiplegic athetosis) .
The combination of athetosis and chorea of all four
limbs is a cardinal feature of Huntington disease and
of a state known as _________ which begins in
childhood
double athetosis,
Localized forms of athetosis may occasionally follow vascular
lesions of the ________ AND _________
lenticular nucleus or thalamus
This term designates an uncontrollable, poorly patterned
flinging movement of an entire limb.
B a l l i s m u s
Bilateral ballismus is infrequent and usually asymmetrical;
here a metabolic disturbance, particularly
__________, is the usual cause
In most cases,
medication with __________ suppresses
the violent movements.
nonketotic hyperosmolar coma
haloperidol or phenothiazine
unnatural spasmodic movement of posture
that puts the limb in a twisted posture
a central
feature is involuntary__________
DYSTONIA
cocontraction of agonist and
antagonist muscles.
Generalized dystonia
is seen in its most pronounced form as an uncommon
heritable disease, __________
which is associated with a mutation in the______
dystonia musculorum deformans,
DYT gene
________
may also be a prominent feature of certain rare
heredodegenerative disorders, such as familial striatal
necrosis with affection of the optic nerves and other parts
of the nervous system.
This process
has a number of names, including _______ AND ________
Widespread torsion spasm (another term for dystonia)
L-dopa-responsive
dystonia and Segawa disease
A characteristic, almost diagnostic, example of the __________consists of retrocollis (forced extension
of the neck), arching of the back, internal rotation of the
arms, and extension of the elbows and wrists-together
simulating opisthotonos.
These reactions respond to some
extent to _________ given two
or three times over 24 to 48 h
druginduced dystonias
diphenhydramine or benztropine
Stereotactic surgery on the _______ and ______, a treatment FOR dystonia
pallidum and ventrolateral
thalamus,
has proved to be the periodic injection of _______
into the affected muscles
botulinum toxin
It is characterized by numerous brief (several minutes)
attacks of choreoathetosis provoked by startle, sudden
movement, or hyperventilation
AD- familial paroxysmal
choreoathetosis.
the attacks take the form of persistent (5 min
to 4 h) dystonic spasms and reportedly have been precipitated by the ingestion of alcohol or coffee or by fatigue but not by movement per se
A favorable response to__________ has been reported, even when the drug is
given on alternate days
(nonkinesigenic type).
benzodiazepines
clonazepam
