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558 SET 7
Terms in this set (72)
What is motor planning?
It represents a strategy of action
What part of the motor system is typically responsible for forming the motor plans?
The higher levels of the motor system, normally in the cerebral cortex
Where are intentions to act formulated?
in the anterior portion of the frontal lobe
Before you can act on intentions, what do they need to be turned into?
In motor planning, how are goals executed by the muscles?
They tend to be setting of spatial and temporal -sequencing-targets rather than explicit commands for which muscles should contract
What regions in the CNS are also involved in motor planning?
the premotor cortex and supplementary motor areas are impt. regions in this network of motor planning
What role does the premotor cortex involved in motor planning?
planning of the limbs, but extent unclear
What concept is thought to involve the premotor cortex in the planning of limbs?
parietal cortex stores the concept or memory of movements and the premotor cortex modifies the concept to a specific motor plan which lower levels of the motor hierarchy execute
For execution of premotor cortex -motor planning what must there be?
Must be communication -for premotor-parietal cortex & premotor cortex- between each of structures to generate a plan for limb movements, particularly visually guided movements
What role does the supplementary motor cortex play in motor planning?
plays a role in planning movements , it responds more to intentions generated by the prefrontal regions -ie-anterior-most portions of the frontal lobe
What is the difference between the premotor cortex and the supplementary cortex?
The premotor cortex responds to external triggers- visual objects to be grasped and is involved in movement planning, the SMA -supplementary motor area- responds more to intention generated by the prefrontal regions -i.e. the anterior-most portions of the frontal lobe- and is involved in motor planning activated by the frontal lobe
What is apraxia?
It is the inability to execute skilled, learned motor acts despite preservation of motor and sensory systems, comprehension, cooperation, and coordination
What causes apraxia?
Issues of weakness or spasticity are usually due to damage to the upper and lower motor neuron pathways--motor planning
How do some texts describe the difference between motor planning and motor programming?
most don't distinguish them differently, and use them interchangeably
How does Van der Merwe describe motor planning and motor programming?
separate processes in production of speech. Motor planning comes first. At this stage motor goals are set, including the order they will occur.
Are the motor goals in Van der Merwe description muscle or articulator specific that occur in motor planning?
they are articulator specific. For example, the motor goal for the production of /l/ would specify the degree of jaw opening, lip shape, etc., but not specific muscles to accomplish these goals. The exact muscle commands happen at a lower level of the motor control system
How would Van der Merwe describe motor planning?
setting sequential "motor goals" which are articulator specific and not muscle specific
How would Van der Merwe describe motor programming?
motor programs are sets of muscle specific commands
What regions of the CNS are believed responsible for motor planning?
primarily in cortical motor association cortex such as the premotor cortex, supplementary motor cortex, Broca's area, parietal association cortex (BA 5 & 7) and portions of the insula and basal ganglia may play a role
What regions of the CNS are responsible for motor programming?
middle of the motor control hierarchy -basal ganglia -caudate and putamen-, cerebellum, premotor and supplementary motor cortex
In Van der Merwe's model, what is the difference in modification between motor programming and motor planning?**
motor programming can be modified and updated in real time during act of speech, while motor plans are not modified in real time
According to Van der Merwe, what does motor programs specify?
muscle tone, direction, force, range, and rate of movement
What is the pyramidal system?
it is a name used to describe the descending motor pathways that originate primarily in the primary motor cortex. The axons that make up these axons descent towards the lower motor neurons of the spinal cord -i.e. corticospinal tract-and the brainstem -corticolbulbar tract
What types of neurons make up the pyramidal system?**
upper motor neurons
What does the pyramidal system pathways do?**
the pathways carry the commands that will be transmitted to the muscles
What is the pyramidal tract responsible for?
execution of voluntary movements
Where does the corticospinal tract originate?
begins in the cerebral cortex
Where does the corticospinal tract terminate?
different levels of the spinal cord, depending on which muscles that portion of the pathway is going to innervate
Where does the corticospinal tract cross over?
it decussates at the lower level of the medulla
What are the effects when the corticospinal tract decussates**
it decusssates at the lower level of the medulla in the brainstem. If this pathway is damaged above the level of the crossing over in the lower medulla, you will see paresis -partial loss of muscle function) or paralysis (total loss of motor function- on the contralateral side. So, a stroke affecting the primary motor cortex in the left hemisphere may result in paresis/paralysis affecting the limbs on the right side. If the damage occurs below the medulla, after the corticospinal pathways have crossed over, then the motor impairments will be ipsilateral -ie on the same side as the damage
Where does the cortiscospinal tract innervate?
If a lesion location is in the cortex in the corticospinal tract, will the limb impairment be contralateral or ipsilateral?**
If a lesion location is in the brainstem in the corticospinal tract, will the limb impairment be contralateral or ipsilateral?**
If a lesion location is in the spinal cord in the corticospinal tract, will the limb impairment be contralateral or ipsilateral?**
Where does the corticobular tract originate?
begins in the cerebral cortex
Where does the corticobulbar pathway terminate?
different cranial nerve nuclei at different levels of the brainstem
What does the corticobulbar innervate?
it innervates all the muscles of the head and neck; all those involved in speech and swallow, except the muscles of respiration
Where does the corticobulbar cross over?
they cross over at the level of the cranial nerve nuclei they are about to innervate
What type of speech does someone with spastic dysarthria have?**
consistent.. consistent degree of hypernasality because it's the direct corticulbulbar that is affected not with issues with motor planing and motor programming
What type of speech does someone with impairments of motor planning or motor programming have? **
issues with factors such as word/phrase length and phonetic complexity
What is spastic dysarthria a result of?**
bilateral damage to the upper motor neurons responsible for innervating muscles of speech production
What happens to the axons as they descend from the cortex that were in the corticospinal and corticobulbar pathways?
they get more tightly packed together
What are the subcortical levels of the pyramidal pathway? and what is their level of descent
the corona radiata-> internal capsule -> and crus cerebri. They also ascent whiter matter pathways. (look at pic. lect. 7-7)
Where are the fiber pathways in the subcortical levels of the pyramidal system so closely packed that they will have a good chance of creating widespread impairments?
lesions in the internal capsule
Know where the upper motor neurons originate
CNS -brain, brainstem, or spinal cord
Where do the upper motor neurons terminate?
Like in Lect. 5
What makes up the direct motor system?**
the corticospinal tract & the corticobulbar tract
Why is it called the direct system?**
the pathways communicate directly with the lower motor neurons and directly transmit the final message that will be sent to the muscles, via the lower motor neurons
Where do lower motor neurons originate?
Where do lower motor neurons terminate?
What is a motor unit?
It consists of lower motor neuron cell body in the spinal cord or brainstem, the axons of these nerve cell bodies that exit the CNS and become the spinal or cranial nerves, the myoneurial junction -ie the point of synapse between the nerve and the muscle- and each individual fiber that is innervated by the nerve
What does paralysis mean?
gross limitation of movement
What is paresis?
What are the signs of upper motor neuron damage?
hypertonia aka spasticity, which has an increase in tone, resistance to passive stretch, and due to damage to indirect reticulospinal pathways.
What is the reticulospinal pathway responsible for?
regulation of REFLEX ACTIVITY by facilitating or inhibiting MOVEMENT and maintaining MUSCLE TONE.
What is assumed to be responsible for spasticity?
What other pathways does the reticularspinal pathway travel close to?
corticospinal and corticobulbar tracts-
What happens when there is damage to the reticulospinal pathway?
there will be increased spasticity, and increased muscle tone due to a lack of inhibition of spinal or brainstem reflexes
What is the hyperrefexia a result of?
It is a result of lack of inhibition of the reflex response
What is hyperreflexia associated with?
-associated with spasticity-
What is hyperreflexia?
exaggerated muscles stretch reflex
What is the effects of UMN damage on speech?
likely contributes to normal muscle tone of oral/facial muscles, which help facilitate execution of rapid, discrete speech movements by the direct activation motor system. Will also result in less activation of LMN and therefore weakness
What is a sign of lower motor neuron (LMN) damage?
is paralysis/ paresis due to significant weakness-hyptonia
What is hypotonia?
it is reduced muscle tone and results in paralysis/paresis due to lower motor neuron damage.
Why would damage to the lower motor neuron cause hypotonia or atrophy of muscles?
because lower motor neurons are the final pathway, and if they are damaged the muscles do not receive a message to contract
What happens with the communication pathway when hyporeflexia occurs?
after the reflex is triggered, the efferent motor pathway will be unable to send a signal for the muscle to contract
What does flaccidity mean?
it is the weakness that is damage to the lower motor neuron
What happens with lower motor neuron damage to the muscles?
they begin to atrophy because they are not receiving innervation
What is fasciculations?
it is damage to lower motor neurons and is due to the dying motor units.
What is hyporeflexia?
another sign of lower motor neuron damage. It is a reduced reflex response.
What part of the body would hyporeflexia be?
on the tongue
Where would damage occur so that hyporeflexia happens?
This happens because whether there is damage to the neuron cell body of the LMN, damage to the peripheral nerve, or involvement of the neuromuscular junciton
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