Motor Circuits Flashcards
Muscles come in pairs: when one contracts, the other ____.
Stretches
Muscle contraction is (active/passive), whereas muscle stretching is (active/passive). What does “passive” mean in this context?
Active
Passive (cannot be directly activated by neurons)
The lower motor neurons are directly involved in receiving information from the ____ ____ and sending information to ____.
Spinal cord
Muscles
The upper motor neurons send information from the ___ ___ and the ___ down to ____ motor circuits.
Motor cortex
Brainstem
Lower
Upper motor neurons can directly synapse on ___ ___ neurons, but usually synapse on ___ ___ neurons.
Lower motor
Local circuit
Where are the local circuit neurons located?
Spinal cord
Local circuit neurons synapse on ____ ____ neurons.
Lower motor
What are 3 types of sensory information that can be passed to the local circuit neurons? Which one comes directly from the muscles?
Proprioceptive (comes directly from muscles)
Pain
Touch
The upper motor neurons are also called the ____ systems.
Descending
The ___ ___ and the ____ send information that combines with the descending systems to regulate movement.
Basal ganglia
Cerebellum
Each muscle has (one/multiple) neuron(s) that control(s) it.
Multiple
Each muscle is made up of multiple ____ ____. Bigger muscles require (more/less/the same) number of these as smaller muscles.
Muscle fibers
More
Each motor neuron controls a different set of ___ ____.
Muscle fibers
What is a motor neuron pool?
All of the neurons that innervate a particular muscle
(Bigger/smaller) muscles and muscles with (low/high) dexterity have more motor neurons.
Bigger
High
Motor neurons have their cell bodies in the ___ ___ of the ___ ____.
Ventral horn
Spinal cord
Motor neurons synapse in the (ipsilateral/contralateral) spinal cord.
Ipsilateral
Muscles’ motor neurons have their cell bodies in (one/multiple) segments in the spinal cord. What type of muscles don’t have their motor neurons’ cell bodies in the spinal cord at all?
Multiple
Eye
The cell bodies of the proximal limb muscles (closer to the body) are located (medially/laterally) in the ventral horn to the cell bodies of the distal limb muscles (further away from the body).
Medially
What is a motor unit?
All of the muscle fibers innervated by the same motor neuron
Each motor neuron innervates (1/ 1 or more) muscle fibers.
1 or more
In general, the larger the motor unit, the (smaller/larger) the motor neuron, the (less/more) muscles contract, and the (lesser/greater) the force generated.
Larger
More
Greater
In muscle physiology, what is considered to be the smallest unit of force?
Motor unit
The greater the motor unit, the (lesser/greater) the force generated.
Greater
By definition, a small motor unit MUST:
A) Be in a small muscle
B) Innervate relatively few muscle fibers
C) Generate a relatively small amount of force
D) Have a small motor neuron
E) All of the above
B) Innervate relatively few muscle fibers
The other answers aren’t part of the definition for a motor unit
What are the 3 types of motor units?
Slow
Fast fatigable
Fast fatigue resistant
Slow motor units:
1) Many or few muscle fibers per motor neuron?
2) Muscle fibers contain many or few mitochondria and blood vessels?
3) Fast or slow to fatigue?
4) What type of muscle movements? Example?
5) High or low threshold of activation?
1) Few
2) Many
3) Slow
4) Sustained, low force muscle movements (example- upright posture)
5) Low threshold
Most of the muscles of the lower back fall into which category of motor unit? Why?
Slow
They are used for standing and sitting
Which of the 3 categories of motor units has tonic activity?
Slow
Fast fatigable motor units:
1) Many or few muscle fibers per motor neuron?
2) Muscle fibers contain many or few mitochondria and blood vessels?
3) Fast or slow to fatigue?
4) What type of muscle movements? Example?
5) High or low threshold of activation?
1) Many
2) Few
3) Fast
4) Brief, high force contraction (example- sprinting)
5) High threshold
Fast fatigue resistant motor units:
1) (Low/intermediate/high) level of energy generation and number of muscle fibers per motor neuron?
2) High or low threshold?
1) Intermediate
2) High
One muscle can have (one type/ all 3 types) of motor unit(s). If all 3, what would differ between them?
All 3
Different percentages of each
What determines the order in which the 3 types of motor circuits are recruited? In which order do they activate?
Threshold
Slow -> fast fatigue resistant -> fast fatigable
Tension when referring to muscles is synonymous with what term?
Contraction
In general, the amount of force a muscle can use is proportional to its level of ____.
Tension/ contraction
How do slow motor units differ from fast fatigue resistant and fast fatigable motor units in terms of force generated and amount of time that maximum contraction can be maintained?
Slow motor units: not much force generated, can sustain maximum contraction for a long period of time
Fast fatigue resistant and fast fatigable: more force generated, but maximum contraction cannot be sustained for a long period of time
Muscle tension/contraction is determined by the ___ ___ frequency of the ____ ___ ___.
Action potential frequency
Alpha motor neuron
The alpha motor neuron controls what?
Motor unit
At a low frequency of action potential firing by an alpha motor neuron, the muscle shows what kind of response? What effect does this yield?
Twitching
Yields basic muscle tone
What happens to the level of force a muscle shows after several alpha motor neuron action potentials? Is this due to the level of contraction changing? If not, what is it due to?
Force increases
Not due to level of contraction changing
Muscle does not relax in between contractions
Does a single action potential from the alpha motor neuron cause a muscle to contract to its maximum? If not, how is maximum contraction force generated?
No- maximum force comes from high rate of action potential firing
When a maximum healthy rate of action potential firing from the alpha motor neuron occurs, what does the graph of time vs force look like?
Slight relaxations between action potentials without return to baseline
In smooth fused tetanus, does the muscle relax between alpha motor neuron action potential firings? Is this considered to be a healthy condition? If not, what conditions is this related to?
No
No
Charley horse, trigger finger
Larger motor units are usually associated with (smaller/larger) motor neurons.
Larger
Larger motor neurons have (less/more) axonal branches.
More
Is motor unit size directly or inversely proportional to dexterity? Would a larger motor unit yield high or low levels of dexterity?
Inversely proportional
Low
In general, the higher the dexterity of a muscle, the (smaller/larger) the motor units and the (smaller/larger) the motor neurons for each motor unit.
Smaller (both)
Compared to a small motor unit, a large motor unit will likely:
A) Be innervated by more neurons
B) Have a larger motor neuron
C) Have more mitochondria per muscle fiber
D) All of the above
B) Have a larger motor neuron
Stimulating muscle at low frequency for long period of time:
1) What type of motor units predominated before stimulation? After stimulation?
2) The alpha motor neurons shifted to become more like those that normally control what type of motor units?
3) What principle did this experiment demonstrate?
1) Before stimulation: fast fatigable
After stimulation: slow
2) Slow motor units
3) Motor unit plasticity
Athletic training can:
A) Change the firing properties of the motor neuron
B) Change the properties of the muscle fiber
C) Change the size of the muscle
D) All of the above
D) All of the above
Training ankle muscle by repeatedly flexing ankle:
1) How did training change the amount of force generated and the amount of time needed to reach maximum force?
2) How did training change the response time and strength of neuronal activity in the muscle?
3) How did training change the action potential firing rate and amplitude of the alpha motor neurons?
4) What principle did this experiment demonstrate?
1) Increased amount of force generated
Decreased amount of time needed to reach maximum force
2) Decreased response time
Increased strength of neuronal activity in muscle
3) Increased action potential firing rate
Increased amplitude
4) Motor unit plasticity
Even the simplest reflex needs to integrate information from ____ and ____ neurons.
Motor
Proprioceptive
Motor neurons: neurons that activate contraction of ___ ___ or ____ ____.
Motor units
Muscle spindles
What are the two types of motor neurons? Which synapses where? Which has a neuromuscular junction?
Gamma motor neurons- synapse in spindle fibers
Alpha motor neurons- synapse on muscle fibers, have neuromuscular junctions
Proprioceptive neurons innervate and sense change in the ___ ___ and the ___ ____ ____.
Muscle spindle
Golgi tendon organ
What 2 proprioceptive sensory neurons innervate the muscle spindle? Which sensory neuron innvervates the Golgi tendon organ? Which has the bigger and faster neuron(s)?
Muscle spindle: Ia and II (biggest and fastest neurons)
Golgi tendon organ: Ib
The proprioceptive sensory neurons Ia, II, and Ib have their cell bodies in the ___ ____ ____.
Dorsal root ganglia
Proprioceptive input ascends through and has its synapses in the (contralateral/ipsilateral) (dorsal/ventral) horn.
Ipsilateral
Ventral horn
Every muscle has how many spindle(s)? Are spindles located on the inside or outside of muscles? Muscle spindles are innervated by which type of motor neuron and which type of proprioceptive sensory neurons? The effect of the motor neuron on the muscle spindle is (contraction/relaxation).
1 Inside Gamma motor neuron Ia and II Contraction
The Golgi tendon organ is located at the junction between the ___ and the ___. What type of sensory neuron innervates it?
Muscle
Tendon
Ib
The proprioceptive sensory neurons Ia, Ib, and II release what type of neurotransmitter?
Glutamate
The Ib sensory neuron with its cell body in the ___ ___ ___ takes information from the ___ ___ ___ to the (ipsilateral/contralateral) ___ ___ and synapses on an ___ ___ that synapses onto the ____ ____ ___, causing muscle (relaxation/contraction).
Dorsal root ganglia Golgi tendon organ Ipsilateral Ventral horn Inhibitory interneuron Alpha motor neuron Relaxation
The Ia sensory neuron with its cell body in the ___ ___ ___ takes information from the ___ ___ to the (ipsilateral/contralateral) ____ ___ and synapses on the ___ ___ ____, causing muscle (relaxation/contraction).
Dorsal root ganglia Muscle spindle Ipsilateral Ventral horn Alpha motor neuron Contraction
Both the gamma and alpha motor neurons have their cell bodies in the (ipsilateral/contralateral) ___ ___.
Ipsilateral
Ventral horn
The gamma motor neuron with its cell body in the ____ ____ is activated by a(n) (ascending/descending) fiber and carries its information to the ___ ___, causing it to (relax/contract).
Ventral horn
Descending
Muscle spindle
Contract
In general, (ascending/descending) controls require fine regulation. Thus, what type of motor neurons give fine motor control?
Descending
Gamma motor neurons
The alpha motor neuron receives input directly from the: A) Ia sensory afferent B) Ib sensory afferent C) Spindle fibers D) Skeletal muscle E) More than 1 of the above
A) Ia sensory afferent
The gamma motor neuron synapses on the: A) Ia sensory afferent B) Ib sensory afferent C) Spindle fibers D) Skeletal muscle E) None of the above
C) Spindle fibers
In general, activation of the Golgi tendon organ leads to muscle (relaxation/contraction), whereas activation of the muscle spindle leads to muscle (relaxation/contraction).
Relaxation
Contraction
The muscle spindle is ____, meaning that it has a thick outer ____ surrounding it.
Encapsulated
Membrane
The Golgi tendon organ is filled with ____ fibers.
Collagen
What are considered to be the two most important proprioceptive mechanoreceptor types?
Muscle spindle
Golgi tendon organ
What type of tactile receptor is also thought to be important for proprioceptive systems? What does it specifically sense?
Ruffini
Skin stretch
Proprioceptive input is important for 3-D ____ of self and coordination of ____.
Perception
Movement
Alpha motor neurons have (free/encapsulated) endings and determine muscle _____.
Free
Contraction
How does the gamma motor neuron regulate the “gain” of the spindle? What does this allow the muscle spindle to sense?
Adjusts spindle length
Muscle stretch
What part of the muscle gives the most information about the stretch of muscles?
Muscle spindle
The Ia sensory neurons are most sensitive to the ____ of stretch, which happens when the body is (moving/still), whereas the II sensory neurons are most sensitive to ____ stretch, which happens when the body is (moving/still).
Velocity
Moving
Sustained
Still
The axons for what sensory function are the fastest conducting?
Proprioceptive
The monosynaptic stretch reflex is considered to be (voluntary/involuntary) movement. Does a reflex involve higher order (i.e. brain) circuits at all?
Involuntary
No
Synergistic muscles in the monosynaptic stretch reflex are those that are activated on the (same/opposite) side of the limb.
Same
Monosynaptic stretch reflex steps:
1) A disturbance such as being jostled on the subway or pouring liquid into a cup being held causes (contraction/stretching) of the muscle
2) Activation of ___ and ____ proprioceptive sensory neurons
3a) Activation of ___ motor neurons on (synergistic/antagonistic) muscles, causing (contraction/relaxation)
AND
3b) Activation of (excitatory/inhibitory) interneurons, causing (inhibition/excitation) of (synergistic/antagonistic) muscles
1) Stretching
2) Ia and II
3a) Alpha
Synergistic
Contraction
3b) Inhibitory
Inhibition
Antagonistic
On what part of the muscle spindle does the gamma motor neuron synapse?
Poles of muscle spindle
The muscle spindle goes slack when the muscle ____ or ____ after stretch. Does it go slack while stretching, or only afterward? What happens to the Ia or II sensory neurons’ ability to receive information about the muscle length while the spindle is slack? What re-adjusts the spindle length?
Relaxes Contracts Only afterward Cannot receive information about muscle length while spindle is slack Gamma motor neuron
What happens to the firing of the Ia and II sensory neurons while the muscle is stretched? What would happen to the firing of these sensory neurons after muscle stretch if there were no gamma motor neurons? How does the gamma motor neuron adjusting the spindle length affect these sensory neurons’ firing? What information is carried from the sensory neurons in this case?
Muscle is stretched: firing is increased
No gamma motor neurons: firing would cease
Gamma motor neuron’s readjustment enables firing to continue
Changes in length of muscle
In general, the more complex the movements, the more active the ___ motor neurons in modulating the ____.
Gamma
Spindle
The (Ia and II sensory neurons/ gamma motor neurons/ both) are considered to be part of the reflex loop controlling the monosynaptic stretch reflex.
Ia and II sensory neurons only
The Golgi tendon organ is sensitive to muscle (stretch/contraction/both).
Contraction only
Contraction of the muscle (shortens/elongates) the Golgi tendon organ and activates the ____ sensory afferent.
Elongates
Ib
What happens to Golgi tendon organ afferent firing when the muscle is stretched? What happens to the firing when the muscle is contracted?
Stretched: firing is slightly above baseline
Contracted: firing is greatly above baseline
How many Golgi tendon organs per muscle?
1
The Golgi tendon organ functions in a (positive/negative) feedback loop to prevent (under-/over-) contraction.
Negative
Over-contraction
Golgi tendon organ activation part 1:
Muscle (contraction/stretching) activates the ____ sensory neurons of the Golgi tendon organ. These neurons carry their information to the ___ ___ of the ___ ____, where they make ___ synapses. What type(s) of neurons are synapsed upon?
Contraction Ib Dorsal horn Spinal cord 2 Excitatory interneuron, inhibitory interneuron
Golgi tendon organ activation part 2:
1) The inhibitory interneuron synapsed upon by the ___ sensory neuron inhibits the ___ motor neurons attached to (synergistic/antagonistic) muscles, causing (contraction/relaxation).
2) The excitatory interneuron synapsed upon by the ___ sensory neuron excites the ___ motor neurons attached to (synergistic/antagonistic) muscles, causing (contraction/relaxation).
1) Ib sensory neuron Alpha motor neurons Synergistic Relaxation 2) Ib sensory neuron Alpha motor neurons Antagonistic Contraction
In the Golgi tendon organ activation pathway, descending pathways can act upon which interneuron, for what effect?
Inhibitory interneuron
Override GTO signal
Strong activity in the Ib sensory afferent will cause the muscle to which it’s attached to (contract/relax).
Relax
Why is contraction considered active and stretch considered passive?
Contraction is caused by a neurological signal, where stretch is not
What 3 things can cause a muscle to stretch?
Actions of opposing muscles
Being thrown off balance
Weight change of something being held
The Ia, Ib, and II sensory neurons all have (ascending/descending/both) pathways.
Ascending (only Ib has descending)
Active contraction activates what part of the muscle and which sensory neuron(s)? Passive stretch activates what part of the muscle and which sensory neuron(s)?
Golgi tendon organ
Ib
Muscle spindle
Ia, II
When stepping on a tack, what two sensory systems are activated? Which one does what?
Nociceptive- trigger reflex to lift leg that has stepped on tack and shift weight to other leg
Proprioceptive: enable shifting of weight to other leg without falling off balance
Stepping on a tack:
1) Nociceptive neurons make synapses in the ____ ___ with ____ that either stay ipsilateral and do what or cross to the contralateral side and do what?
2) The ipsilateral neurons decrease the activity of the (extensor/flexor) muscle and increase the activity of the (extensor/flexor) muscle in the ipsilateral leg.
3) The contralateral neurons increase the activity of the (extensor/flexor) muscle and decrease the activity of the (extensor/flexor) muscle in the contralateral leg.
1) Spinal cord Interneurons Ipsilateral: trigger movement of ipsilateral leg Contralateral: prepare contralateral leg to receive full body weight 2) Extensor Flexor 3) Extensor Flexor
Toxins such as botox and tetanus toxin (relax/contract/either) muscles through ___ of ___ ___. If applied in the spinal cord, what could be blocked?
Either
Inhibition
Vesicle fusion
Reflexes
Proprioceptive pathways can ascend (ipsilaterally/contralaterally/either) up to the brain. What does this enable?
Either
Coordination of both sides of body
Local circuit neurons include what type of neurons and have their cell bodies and axons where?
Interneurons
Spinal cord
The brainstem controls what type of movements and control of what?
Basic movements
Posture
The upper motor neurons of the cortex get information from which 2 areas? These areas are responsible for ____ and yielding precise ____ of ____ ____ movement.
Motor cortex Premotor cortex Planning Control Complex voluntary
The upper motor neurons of the brainstem get information from what 3 areas?
Vestibular nucleus
Reticular formation
Superior colliculus
The vestibular nucleus of the brainstem gives information about body ____ and ___.
Posture
Position
The reticular formation of the brainstem, like the vestibular nucleus, gives information about body ___ and ___. Additionally, it coordinates autonomic and somatic ____ motor movements. What is an example of this type of movement?
Posture
Position
Stereotyped
Walking
The superior colliculus of the brainstem orients movement of the ___ and ___.
Head
Eyes
The primary motor cortex is (rostral/caudal) to the central sulcus. The premotor cortex is (rostral/caudal) to the primary motor cortex.
Rostral (both)
Similar to the somatosensory cortex, the motor cortex has a topographical representation of the body called the ___. A disproportionate part of the motor cortex corresponds to the ____ and ____, which require fine motor control.
Homunculus
Hands
Mouth
Information from the motor cortex descends via 2 major tracts:
1) _____ tract synapses in the ____ ____ to control the ____.
2) _____ tract synapses in the ___ ____ to control the ___ and ___.
1) Corticospinal tract Spinal cord Body 2) Corticobulbar tract Cranial nerves Face and mouth
The premotor cortex has reciprocal connections with the ___ ___.
Motor cortex
The premotor cortex can project to ___ circuits in the ___ ___.
Local
Spinal cord
The premotor cortex is involved in ____ movements. What is an example of this?
Conditional
Press lever after bell rings
The premotor cortex is important for the _____ and ____ of motor activity as well as _____ of _____ motor tasks, such as ___.
Initiation Selection Coordination Complex Talking
The cortical projection neurons are arranged in layers from most superficial near ____ surface to deepest near ____ and ____ ____ ____, which carry axons out.
Cortical
Ventricles
White matter tracts
The cortical projection neurons of focus have cell bodies in layers ____ and ____ of the cortex and project their axons to the ____ and ____ ____.
V
VI
Brainstem
Spinal cord
The cortical projection neurons have afferents for many different regions of the brain, including the ____, ____, and _____.
Brainstem
Thalamus
Cortex
The cortical projection neurons are the (smallest/largest) neurons in the cortex and are (excitatory/inhibitory).
Largest
Excitatory
Nissl stain identifies what cellular structure and is used to identify what type of projection neurons in the cortex?
Ribosomes
Betz cells
The Betz cells are the (smallest/largest) projection motor neurons in layer ___ of the cortex and send their axons in some cases all the way down the ____ ____.
Largest
V
Spinal cord
Upper motor neurons of the cortex that project along the corticobulbar tract will cross to the contralateral side where? These motor neurons control the ___ ___ of the ___.
Brainstem
Cranial nerves
Face
The upper motor neurons of the cortex that project along the corticospinal tract will cross to the contralateral side where? They descend through the ___ ____ ___ of the ___ ___ and synapse on ___ ____ ____ in the (medial/lateral) ___ ____. These neurons control the (proximal/distal) ____ muscles.
Pyramidal decussation Lateral white matter Spinal cord Lower motor neurons Lateral Ventral horn Distal Limb
The upper motor neurons of the brainstem descend (ipsilaterally/contralaterally) through the ____-____ ____ ___ of the ___ ___. They make _____ synapses on ___ ___ ___ in (ipsilateral/contralateral/both) sides of the (medial/lateral) ___ ____. These neurons control the (proximal/distal) ____ muscles, which control ___ and ____.
Ipsilaterally Anterior-medial white matter Spinal cord Bilateral Lower motor neurons Both Medial Ventral horn Proximal Limb Posture Balance
What percent of corticospinal projection neurons cross to the contralateral side? What percent remain ipsilateral?
90%
10%
In the corticospinal tract, ____% of the axons cross to the contralateral side in the ____ ____ of the ____ and form the (lateral/ventral) corticospinal tract. Neurons in this tract that control the ___ and ____ may synapse directly onto ____ ____ ____, but most synapse onto ___ ____ ___.
90% Pyramidal decussation Medulla Lateral Forearm Hand Alpha motor neurons Local circuit neurons
In the corticospinal tract, ____% of the axons remain ipsilateral and form the (lateral/ventral) corticospinal tract. Neurons in this tract synapse (monolaterally/bilaterally) and are important for control of ____ and ____ limb muscles.
10% Ventral Bilaterally Axial Proximal
Axial limb muscles are directly involved in regulating ____ as well as regulating ____ muscles such as shoulder and hip muscles.
Posture
Proximal
In the corticobulbar tract, the axons descend (ipsilaterally/contralaterally) and synapse (monolaterally/bilaterally) in what 2 areas of the brain?
Ipsilaterally
Bilaterally
Pons, medulla
Axons from the corticobulbar tract can synapse on the ___ ___ nucleus (cranial nerve ___) or the ___ ___ nucleus (cranial nerve ___) of the ____, or synapse on the ____ nucleus (cranial nerve ____) of the ____.
Trigeminal motor nucleus Cranial nerve V Facial motor nucleus Cranial nerve VII Pons Hypoglossal nucleus Cranial nerve XII Medulla
The corticobulbar tract carries information from the (ipsilateral/contralateral) motor cortex (face/body) area.
Ipsilateral
Face
True or false: the corticospinal tract axons all cross the pyramidal decussation.
False
A single medial local circuit neuron can innervate (few/many) segments of the spinal cord. Medial local circuit neurons make (ipsilateral/contralateral/both) connections on motor neurons in (medial/lateral) portions of the ventral horn. What kind of muscle function do they control?
Many
Both
Medial
Posture
A single lateral local circuit neuron can innervate (few/many) segments of the spinal cord. Lateral local circuit neurons make (ipsilateral/contralateral/both) connections on motor neurons in the (medial/lateral) portions of the ventral horn. What kind of muscle function do they control?
Few
Ipsilateral
Lateral
Fine control of distal extremities (e.g. arms and fingers)
A patient that has difficulty standing upright but can play the piano well is more likely to be having disruption of their (lateral/medial) local circuit neurons.
Medial
Both the ____ cortex and the ___ cortex can control the facial muscles.
Motor cortex
Cingulate cortex
Axons from the cingulate motor cortex descend on the (ipsilateral/contralateral/both) side(s). Thus, information from the (ipsilateral/contralateral/both) sides of the cingulate motor cortex can control the contralateral side of the face.
Both
Both
Damaging the motor cortex or the corticobulbar projections would affect the (upper/lower/both) (ipsilateral/contralateral/both) facial muscles.
Lower
Contralateral
The facial nerve (cranial nerve VII) is considered to be a(n) (upper/lower) motor neuron.
Lower
Damaging the facial nerve (cranial nerve VII) or what other area(s) would affect the (upper/lower/both) (ispilateral/contralateral/both) facial muscles.
Both sides of cingulate cortex
Both
Contralateral
Neurons of the vestibulospinal tract have their cell bodies in the ___ ___ and synapse in one or more parts of the ____ ____. They make (monolateral/bilateral) connections.
Vestibular nucleus
Spinal cord
Bilateral
The medial vestibular nuclei regulate ____ position by reflex movement of the ___ muscles. They respond to stimulation of the ____-____ ____ of the vestibular system.
Head
Neck
Semi-circular canals
The lateral vestibular nuclei facilitate activation of the ____ extensor muscles. They respond to activation of the ___ ____ of the vestibular system.
Limb
Otolith organs
Both the medial and lateral vestibular nuclei maintain ____ in response to disturbances of this.
Posture
The vestibular nuclei receive information coming from the _____ nerve, or cranial nerve ____.
Vestibulocochlear nerve
VIII
The reticulospinal tract is involved in (voluntary/involuntary) ____ adjustment. It is made up of (a few/many) (small/large) nuclei.
Involuntary
Postural
Many
Small
The reticular formation is involved in ____ and ____ control, coordination of ___ movements, regulation of ___ and ____, and temporal and spatial control of ____ and ___ movements for rhythmic motion such as ____.
Cardiovascular Respiratory Eye Sleep Wakefulness Limb Trunk Walking
The neurons of the reticulospinal tract primarily synapse on ___ ____ neurons. The reticulospinal tract neurons make (monolateral/bilateral) connections.
Local circuit
Bilateral
Like the vestibular nuclei, the nuclei of the reticular formation maintain ____ in response to disturbances of this.
Posture
The reticulospinal tract goes through the ____, ____, and ____, always in approximately the same position in each of these regions.
Midbrain
Pons
Medulla
The reticular formation nuclei can assigned to what 2 categories according to their function?
Modulatory
Premotor
Which of the following tracts synapse bilaterally in the spinal cord? A) Corticobulbar B) Reticulospinal C) Vestibulospinal D) Two of the above E) All of the above
D) Two of the above
Reticulospinal and vestibulospinal; corticobulbar synapses in brainstem
Information from the primary motor cortex and premotor cortices, in addition to descending along the corticospinal tract, can be carried to the ____ ____, where it synapses (monolaterally/bilaterally) and is then carried into the (lateral/medial) spinal cord and synapses (monolaterally/bilaterally). This information is used to control ____ adjustments.
Reticular formation Bilaterally Medial Bilaterally Postural
When a person is told to pull a lever following hearing a bell chime, does the person move their arm first or their leg first? Why?
Leg- must adjust posture before pulling lever, or will fall off balance
When a person is told to pull a lever following hearing a bell chime, the movement of the arm muscle is considered to be (voluntary/involuntary) and is controlled by neurons of the _____ tract. The movement of the leg muscle is considered to be (voluntary/involuntary) and is controlled by neurons of the _____ tract.
Voluntary
Corticospinal tract
Involuntary
Reticulospinal tract
True or false: voluntary motor control requires premotor and motor activity, whereas involuntary motor control requires only the motor cortex.
False
Upper motor neuron syndrome corresponds to damage of the ___ cortex, the ____ cortex, or the _____ tract. Lower motor neuron syndrome corresponds to damage to ____ or ____ motor neurons.
Motor cortex Premotor cortex Corticospinal tract Alpha Gamma
Damage to upper motor neurons would result in muscle (weakness/paralysis/both), whereas damage to lower motor neurons could result in (weakness/paralysis/both).
Weakness only
Both
Damage to upper motor neurons would result in (mild to no/severe) muscle atrophy, whereas damage to lower motor neurons would result in (mild to no/severe) muscle atrophy.
Mild to no
Severe
When upper motor neurons are damaged, an initial period of ____ ____ occurs, in which there is (hyperactive/no) movement. This period is followed by (hypoactive/hyperactive) reflexes. What causes the change in reflexes?
Spinal shock
No
Hyperactive
Loss of descending input to inhibitory interneurons
During the secondary occurrence of hyperactive reflexes following upper motor neuron damage, there is (decreased/increased) muscle tone, fluctuation between ___ and ____ (also called ____), and muscle ____.
Increased Relaxation Contraction Clonus Rigidity
While upper motor neuron damage yields (hypoactive/hyperactive) reflexes, lower motor neuron damage yields (hypoactive/hyperactive) reflexes. Why does the change in reflexes occur in lower motor neurons?
Hyperactive
Hypoactive
Lower motor neurons (i.e. alpha motor neurons) control reflexes
Do the initial signs and symptoms of lower motor neuron damage change as time goes on, or do they persist? In lower motor neuron damage, distribution of symptoms corresponds to site of ____.
Persist
Damage
Upper motor neuron damage causes loss of (reflexive/voluntary/both) movement, whereas lower motor neuron damage causes loss of (reflexive/voluntary/both) movements.
Voluntary
Both
What is a normal Babinski response to tickling of foot (i.e. what do the toes do)? In a baby less than 4 months old, tickling the foot causes the toes to do what? Why is this? Would a person with upper or lower motor neuron damage exhibit a Babinski response like that of a young baby?
Curl toes down
Toes curl up
Upper and lower motor neurons are not yet connected
Upper motor neuron damage
The neurons of the cingulate cortex control the muscles of what area of the face?
Forehead
