3. Motor Paralysis Flashcards
Within a few days after interruption of a motor nerve, the individual denervated muscle fibers begin to contract spontaneously. This isolated activity is called __________ & it cannot be seen through intact skin, but can be recorded as a small, repetitive, short-duration potential in EMG.
Fibrillation
When a motor neuron becomes diseased, it may manifest increased irritability and all the muscle fibers that it controls may discharge sporadically. The result of contraction of 1 or several such motor units is a visible twitch called __________ that appears in EMG as a large spontaneous muscle action potential.
Fasciculation
Simultaneous/ sequential spontaneous contractions of multiple motor units cause a rippling of muscle known as __________
Myokimia
These are large motor neurons of the anterior horn
Alpha motor neurons
These are small anterior horn cells whose axons terminate on the small intrafusal muscle fibers within the spindles
Gamma motor neurons
These motor neurons effect contraction of both spindle & nonspindle fibers
Beta motor neurons
These are the main neurotransmitters of the descending corticospinal tract
Aspartate
Glutamate
This is the neurotransmitter released by Renshaw cells, which are responsible for recurrent inhibition, and by interneurons that mediate reciprocal inhibition during reflex action
Glycine
This serves as the inhibitory neurotransmitter of interneurons in posterior horns
GABA
These are released by primary afferent terminals & interneurons & act specifically on excitatory amino acid receptors
L-glutamate
L-aspartate
This is the only direct long-fiber connection between the cerebral cortex & the spinal cord
Corticospinal tract
The primary motor cortex/ precentral gyrus corresponds to Brodmann area ___
4
The primary somatosensory cortex corresponds to Brodmann areas __________
3, 1, 2
What is the essential feature of spasticity?
A velocity-dependent increase in resistance of muscles to a passive stretch stimulus
If the muscles are briskly stretched, the limb moves freely for a very short distance, beyond which there is an abrupt catch and then a rapidly increasing muscular resistance up to a point; then, as passive extension of the arm or flexion of the leg continues, the resistance melts away. This sequence is called __________
Clasp-knife phenomenon
What is the most sensitive indication of an UMN lesion?
Babinski sign
This is a series of rhythmic involuntary muscular contractions occurring at 5-7 Hz in response to an abruptly applied and sustained stretch stimulus
Clonus
This is a state in which an 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
Failure to conceive or formulate an action, either spontaneously or on command; characterized by difficulty in “what to do”
Ideational apraxia
The patient may know & remember the planned action but because these areas or their connections are interrupted, he cannot actually execute it with either hand; a block in “how to do”
Ideomotor apraxia
An ill-defined clumsiness & maladroitness that is the result of an inability to connect or isolate individual movements of the hand & arm
Limb-kinetic apraxia
Which lobe embodies the property of praxis?
Dominant parietal lobe
The most common of all apraxias in practice, characterized as inability to carry out facial movements on command
Oral-buccal-lingual apraxia
What is the most common cause of monoplegia without muscular atrophy?
A cerebral vascular lesion
This is the most common form of paralysis
Hemiplegia
What is the most common cause of acute paraplegia or quadriplegia?
Spinal cord trauma
What are the identifying characteristics of spasticity?
A predilection for involvement of certain muscle groups
A specific pattern of response of muscles to passive stretch
Manifest exaggeration of tendon reflexes
