Motor Control and Motor Unit Flashcards
Which muscle type does the following characterization describe?
Upper limit for twitch tension is low
Slow twitch
Which motor unit does the following description characterize?
Current threshold for activation is high
FF MU
Which type of movement occurs without any neural input?
Passive movement
Which muscle type does the following characterization describe?
Energy source is aerobic and anaerobic glycolysis
Oxidative glycolytic fast twitch
What is a fasciculation?
Visible twitches that result from the activation of an entire motor unit
True or False: Stereotyped movement does NOT depend on central pattern generators
FALSE.
Stereotyped movement depends on central pattern generators.
Define motor pool
alpha-motor neurons that innervate a single muscle
Which motor unit does the following description characterize?
Low upper limit for tetanic tension
S MU
What is the maximal duration of continuous activation of glycolytic fast twitch fibers
5 minutes or less
What is the maximal duration of continuous activation of FF motor units?
5 mins or less
How many motor neurons control a typical muscle?
100
Which muscle fiber makes up a motor unit that can be described as “fatigue-resistant”
Oxidative glycolytic fast twitch
What is the smallest division of movement?
Motor unit
Which motor unit does the following description characterize?
Input resistance is low
FF MU
Which muscle type does the following characterization describe?
Maintains force for short periods of time
Fast twitch
Which muscle type does the following characterization describe?
Less vascularized
Fast twitch
In the absence of neural input,
A) None of the fibers in the motor unit contract
B) Some of the fibers in the motor unit contract
C) All of the fibers in the motor unit contract
A) None of the fibers in the unit contract
Which motor unit does the following description characterize?
Intermediate upper limit for tetanic tension
FR MU
Which muscle type does the following characterization describe?
pale in color
Fast twitch
Which motor unit does the following description characterize?
Maximal duration of continuous activation is hours
S MU
Which muscle type does the following characterization describe?
Speed of contraction is intermediate
Oxidative glycolytic fast twitch
Gazing at a painting or gasping at a story told by a friend are both examples of what?
Self-generated actions
Which has more fast twitch fibers proportionally, the soleus or the orbicularis oculi?
Orbicularis oculi
Small, slow units are active during smooth control/poor control
Smooth control
What is a self-generated action?
Occurs in response to a stimulus, removed from a sensory input
Which motor unit does the following description characterize?
Current threshold for activation is low
S MU
Complete dysfunction in MN, NMJ, or muscle - muscles have no tone.
This description best characterizes which of the following?
A) Akinesia B) Spastic paralysis C) Volitional Paresis D) Flaccid Paralysis E) Emotional Paresis
D) Flaccid paralysis
Which muscle type does the following characterization describe?
Upper limit for twitch tension is high
Glycolytic fast twitch
Lack of movement, damage to the basal ganglia - seen in severe PD patients
This description best characterizes which of the following?
A) Akinesia B) Spastic paralysis C) Volitional Paresis D) Flaccid Paralysis E) Emotional Paresis
A) Akinesia
Define A-reflexia
Lack of reflexes
Which muscle type does the following characterization describe?
Can be large because force depends on cross sectional area
Fast twitch
Which motor unit does the following description characterize?
High upper limit for tetanic tension
FF MU
Which motor unit does the following description characterize?
Rise time is intermediate
FR MU
Which muscle type does the following characterization describe?
Speed of contraction is fast
Fast twitch fibers
Which muscle type does the following characterization describe?
Upper limit for twitch tension is intermediate
Oxidative glycolytic fast twitch
Which muscle type does the following characterization describe?
Requires oxygen to function
Slow twitch; oxidative glycolytic fast twitch CAN use oxygen, but does not require it.
Which type of movement involves the coordinated function of various muscles and motor commands to control for fatigue, balance, weight (load)
Smooth movement
Which muscle type does the following characterization describe?
Speed of contraction is slow
Slow-twitch
Small, slow units are active during low/high force contractions
Low force contractions
Why would fasciculations get larger after denervated muscle wasting?
Because the surviving motor neurons will rennervate the surviving fibers
When a motor unit fires,
A) None of the fibers in the unit contract
B) Some of the fibers in the unit contract
C) All of the fibers in the unit contract
C) All of the fibers in the unit contract
Which muscle type does the following characterization describe?
Contains glycogen stores
Fast twitch
What part of the brain does volitional action involve?
Central cortex
Which muscle type does the following characterization describe?
Tires quickly
Fast twitch
Large fast units are active during smooth control/poor control
Poor control
Which motor unit does the following description characterize?
Input resistance is intermediate
FR MU
A-Reflexia results from a lesion in which of the following? A) Basal ganglia B) Descending motor tracts C) Motor neurons D) Motor interneurons
C) Motor neurons, as well as the NMJ and muscle
Which motor unit does the following description characterize?
Made of oxidative glycolytic fast twitch fibers
FR MU
Which muscle type does the following characterization describe?
Not very large
Slow twitch
Define motor unit
1 motor neuron + fibers it innervates
Are reflexes affected by voluntary control?
NO
Which motor unit does the following description characterize?
Current threshold for activation is intermediate
FR MU
Which muscle type does the following characterization describe?
Energy Source is aerobic only
Slow twitch
What would denervated muscles look like on EMG?
Would show fasciculations
Which muscle type does the following characterization describe?
Upper size limit is intermediate
Oxidative glycolytic fast-twitch
Which type of movement is involved with postural control and micturition
Stereotyped movement
Give an example of a muscle that does tonic movement - ongoing for long periods of time, postural
Soleus ( in the leg )
Which muscle type does the following characterization describe?
Has a lot of mitochondria
Slow twitch
True or false: There is increasing tension as more muscle units are recruited
TRUE
Which type of movement depends on skeletal muscles
Voluntary movement
What is the maximal duration of continuous activation for oxidative glycolytic fast twitch fibers?
30 mins or less
Which muscle type does the following characterization describe?
Upper size limit is small
Slow twitch fibers
Define reflex
Simple movement in reaction to stimuli (usually painful)
What causes a deficit of passive movement
Central problems
What is the maximal duration of continuous activation for FR motor units?
30 mins or less
What is the term for the inability to perform emotional actions?
emotional paresis
Large, fast units are active during low/high force contractions
High
Which motor unit does the following description characterize?
Innervation ratio is low
FR MU
How does compensation work?
Increases discharge frequency of remaining neurons that are part of a partially lost motor pathway
Which motor unit does the following description characterize?
Innervation ratio is the highest
FF motor units
Which has a larger fiber size, the soleus or the orbicularis occuli?
Soleus
Which muscle type does the following characterization describe?
Generates force slowly
Slow twitch
Which muscle type does the following characterization describe?
Generates large force
Fast twitch
Hyper-reflexia results from a lesion in which of the following? A) Basal Ganglia B) Descending Motor Tracts C) Motor Neurons D) Motor Interneurons
B) Descending motor tracts
Which muscle type does the following characterization describe?
Anaerobic glycolysis only
Glycolytic fast twitch
What are the two categories of self-generated actions?
Volitional and emotional
The fibers in a single MU are
A) Homogenous (i.e., all fast twitch)
B) Heterogenous (i.e., some fast twitch, some slow twitch)
A) Homogenous
What part of the brain does emotional action involve?
Cortex
Which type of movement is LESS accurate, fast or slow movements?
Fast
Which muscle fiber makes up a motor unit that can be described as “fast fatigable”
Glycolytic fast twitch
What results from spinal poliomyelitis?
Motor neuron death + muscle weakness and flaccid paralysis
Which muscle type does the following characterization describe?
Maintains force for a long time
Slow twitch
What confers the “biochemical type”
The motor neuron that innervates the fibers
Define hyperreflexia
Exuberant reflexes
Which motor unit does the following description characterize?
Rise time is fast
FF MU
Which type of movement is semi-automatic and has rhythmic behaviors?
Stereotyped movement
What would a deficit of passive movement look like?
Resistance to movement
What is the rise time of S motor units?
50-100 ms
Give an example of a muscle that does phasic (burst activity) movement - fast, short-lived
Obicularis oculi
Lesion in the corticospinal pathway or supplementary area. Involves hyper-reflexia
This description best characterizes which of the following?
A) Akinesia B) Spastic paralysis C) Volitional Paresis D) Flaccid Paralysis E) Emotional Paresis
B) Spastic paralysis
What is the rise time of FR motor units?
30-50 ms
Lesions in the basal ganglia result in what?
Rigidity (felt as constant resistance) - commonly found with deficits of passive movement
Which motor unit does the following description characterize?
Made of glycolytic fast twitch fibers
FF MU
Muscle control is done by
A) Slow twitch muscle fibers
B) Motor pools
C) Motor neurons
D) Motor units
B) Motor pools
Lesions in the descending motor tracts (UMN) result in what?
Spasticity (initial resistance, then relative ease of movement) - commonly found with deficits of passive movement
In spinal poliomyelitis, do muscles have increased or decreased MU recruitment?
Decreased
What is volitional paresis?
Absence of voluntary movements only
Which motor unit does the following description characterize?
Rise time is slow
S MU
Which muscle type does the following characterization describe?
Maximal duration of continuous activation is hours
Slow twitch
Which muscle type does the following characterization describe?
Contains Myoglobin
Slow twitch
Define compensation
Allows for continued muscle function even with a partial loss in a motor pathway
What is Henneman’s size principle?
Maximal force depends on the number of fibers recruited
What is the rise time of FF motor units?
3-30 ms
Which motor unit does the following description characterize?
Input resistance is high
S MU
Motor units are/are not mixed in fibers, while muscles are/are not mixed in fibers
Motor units are NOT mixed in fibers, while muscles ARE mixed in fibers
Which motor unit does the following description characterize?
Made of slow-twitch fibers
S MU
Which muscle type does the following characterization describe?
Upper size limit is large
Glycolytic fast twitch
Which motor unit does the following description characterize?
Innervation ratio is the lowest
S motor units