Term
| what are the 2 main classes of UMNs |
|
Definition
| ones that begin in the motor/premotor cortex and the ones that begin in the brainstem |
|
|
Term
| what are UMNs that originate in the motor cortex responsible for? |
|
Definition
| planning and controlling voluntary movements |
|
|
Term
| what are UMNs that originate in the brainstem responsible for? |
|
Definition
| ongoing postural control and navigation |
|
|
Term
| what do all UMNs synapse on? |
|
Definition
| either interneurons or LMNs |
|
|
Term
| which type of UMNs are responsible for skilled voluntary movements of typing, playing piano, catching a ball |
|
Definition
| UMNs that originate in the motor cortex |
|
|
Term
| where is the motor cortex |
|
Definition
|
|
Term
| what are the 3 UMN pathways that originate in the cortex? |
|
Definition
| lateral corticospinal tracts, ventral corticospinal tracts, corticobulbar tracts |
|
|
Term
| what are the 4 UMN pathways that originate in the brainstem |
|
Definition
| vestibulospinal tract, reticulospinal tract, colliculospinal tract, rubrospinal tract |
|
|
Term
| what is the ultimate target of UMNs? |
|
Definition
|
|
Term
| how are LMNs arranged in the spinal cord |
|
Definition
| somatotopically in the ventral horn |
|
|
Term
| are axial LMNs medial or lateral in the spinal cord |
|
Definition
|
|
Term
| are distal limb motor neuron pools medial or lateral in the spinal cord |
|
Definition
|
|
Term
| how are local circuit neurons organized |
|
Definition
|
|
Term
| where are interneurons located? |
|
Definition
| in the intermediate zone/Rexed Layer VII of the gray matter |
|
|
Term
| what do medial interneurons innervate |
|
Definition
| medial regions of the ventral horn = LMNs of axial and proximal muscles |
|
|
Term
| where in the intermediate zone/Rexed layer VII are the medial interneurons located |
|
Definition
|
|
Term
| what are long distance circuit |
|
Definition
| medial interneuron axons that can extend for multiple segments |
|
|
Term
| what is a medial interneuron axon that goes from C3 to S3? |
|
Definition
|
|
Term
| what do medial interneuron axonal branches sometimes do? |
|
Definition
| cross the midline to innervate LMNs in the medial part of the contralateral cord |
|
|
Term
| what is the purpose/function of medial internuron axonal branches that cross the midline to innervate contralateral LMNs? |
|
Definition
| ensures that both groups of axial muscles on both sides of the cord can act together to adjust and maintain posture |
|
|
Term
| what interneruons is Elaine from Seinfeled missing? |
|
Definition
|
|
Term
| what do lateral interneurons innervate? |
|
Definition
| innervate lateral regions of the ventral horn and therefore LMNs of distal muscles |
|
|
Term
| where are lateral interneurons located |
|
Definition
| laterally, in the intermediate zone |
|
|
Term
| why are lateral interneurons sometimes called short distance circuits? |
|
Definition
| because their axons extend over a few segments |
|
|
Term
| where do lateral interneurons terminate? |
|
Definition
| same side of the spinal cord |
|
|
Term
| what is the functional result of lateral interneuron connections? |
|
Definition
| finer control of distal musculature/manipulative tasks |
|
|
Term
| which interneurons synapse in intermediate/lateral motor neuron pools? |
|
Definition
|
|
Term
| can medial interneurons cross over the spinal cord? |
|
Definition
|
|
Term
| can lateral interneurons cross over the spinal cord? |
|
Definition
|
|
Term
| is it a bad thing that lateral interneurons don't corss over the spinal cord? |
|
Definition
| no, we don't want our hands to have to do the same things. |
|
|
Term
| what are most UMNs that project to the medial part of the ventral horn or to medial interneurons primarily concerned with? |
|
Definition
|
|
Term
| where do the medially projecting UMNs concerned with postural mechanisms primarily arise from? |
|
Definition
|
|
Term
| what are the 3 UMN pathways that originate in the brainstem, project medially, and are primarily concerned with postural mechanisms? |
|
Definition
| vestibulospinal tract, reticulospinal tract, colliculospinal tract |
|
|
Term
| from what nucleus and in what part of the brain does the vestibulospinal tract originate? |
|
Definition
| vestibular nuclei, brainstem |
|
|
Term
| from what nucleus and in what par to fthe brain does the reticulospinal tract originate |
|
Definition
| reticular formation, brainstem |
|
|
Term
| from what nucleus and what part of the brain does the colliculospinalt ract originate |
|
Definition
| superior colliculus, brainstem |
|
|
Term
| what are most UMNs that project to the lateral part of the ventral horn primarily concerned with? |
|
Definition
|
|
Term
| where do laterally projecting UMNs arise from? |
|
Definition
|
|
Term
| what do we call the pathway of laterally projecting UMNs? |
|
Definition
| lateral corticospinal tracts |
|
|
Term
| what are the 2 UMN motor control centers that begin in the brainstem and help maintain balance and posture? |
|
Definition
| vestibulospinal tract, reticulospinal tract |
|
|
Term
|
Definition
| hearing, balance, equilibrium |
|
|
Term
| what are the 2 parts of CN VIII |
|
Definition
| cochlear nerve, vestibular nerve |
|
|
Term
| function of cochlear nerve |
|
Definition
|
|
Term
| function of vestibular nerv |
|
Definition
|
|
Term
| to what nuclei does sensory information from the semicircular canals in the inner ear project |
|
Definition
|
|
Term
| what kind of sensory information comes from the semicircular canals in the inner ear |
|
Definition
| position and angular acceleration of the head => balance and equilibrium |
|
|
Term
| what do we call the UMN axons from the vestibular nuclei |
|
Definition
|
|
Term
| where do the vestibulospinal tracts project |
|
Definition
| mainly to the medial regions of the spinal cord gray matter that control axial limb muscles |
|
|
Term
| where in the brainstem are the vestibular nuclei |
|
Definition
|
|
Term
| what do the semicircular canals tell the vestibualr nuclei all day long |
|
Definition
| where the head is in space |
|
|
Term
| what is the medial vestibulospinal tract |
|
Definition
| axons from the vestibular nuclei that project to the medial spianl cord and control axial muscles |
|
|
Term
| what is the lateral vestibulospinal tract |
|
Definition
| axons from the vestibular nuclei that project to the lateral spinal cord and control axial muscles (not as many of these as medial vesitbular tracts) |
|
|
Term
| what/where is the reticular formation |
|
Definition
| a complicated network/cluster of neurons located in the core of the brainstem |
|
|
Term
| what are the functions of the reticular formation |
|
Definition
| cardiovascular, respiratory, sleep/wake cycle, motor control |
|
|
Term
| what do we call the UMN axons from the reticular formation |
|
Definition
|
|
Term
| where do reticulospinal tracts go |
|
Definition
| from reticular formation to the medial parts of the gray matter in spinal cord |
|
|
Term
| what kinds of muscles does the reticular formation coordinate |
|
Definition
|
|
Term
| where are the neurons of the reticular formation (be specific of which parts of the brainstem) |
|
Definition
|
|
Term
| what do the vestibulospinal tracts do |
|
Definition
| ensure rapid response to postural changes detected by the inner ear - lightning fast, helps us stay upright |
|
|
Term
| what do the reticulospinal tracts do |
|
Definition
| initiate adjustments that stabilize posture before and during ongoing movements |
|
|
Term
| which UMN tract helps anticipate that you might lose balance |
|
Definition
|
|
Term
| if you're standing and will pull a lever with your bicep, what role will the reticulospinal tracts play in this activity |
|
Definition
| reticular formation anticipates that some postural instabliity is about to occur and contracts the gastroc to counteract the anticipated loss of balance. |
|
|
Term
| which tract is for feedback of postural information |
|
Definition
|
|
Term
| which tract is for feedforward postural stability |
|
Definition
|
|
Term
| as part of the motor planning for movement, where are movements evaluated for their potential effects on the body's stability |
|
Definition
|
|
Term
| as part of the motor planning for movement, which tract will cause a contraction to stabilize the body in anticipation of another movement that will decrease stability |
|
Definition
|
|
Term
| do feedforward postural responses by the reticular formation occur before or after limb movement |
|
Definition
| feedforward postural responses by the reticular formation typically precede the onset of limb movement |
|
|
Term
| what are direct cortical projections |
|
Definition
| UMNs that project directly from the cortex to the spinal cord, such as activating the contraction of the bicep to pull a lever |
|
|
Term
| where do collateral branches from direct cortical projections terminate |
|
Definition
| within brainstem regions such as the reticular formation and/or nuclei such as the vestibular nuclei |
|
|
Term
| what are indirect cortical projections |
|
Definition
| branches from direct cortical projections that terminate in certain brainstem regions such as the reticular formation and/or nuclei such as the vestibular nuclei |
|
|
Term
| what are the 2 routes through which the motor cortex can influence LMNs in the spinal cors |
|
Definition
| direct and indirect routes |
|
|
Term
| in what part of the brainstem is the superior colliculus located |
|
Definition
|
|
Term
| where do colliculospinal axons project |
|
Definition
| from superior colliculus to medial ventral horn in the cervical spinal cord |
|
|
Term
| what is the function of the colliculospinal tract |
|
Definition
| control axial muscles in the neck and influence the movements of the head in reference to visual stimuli |
|
|
Term
| what is another term for the colliculospinal tract |
|
Definition
|
|
Term
| where in the brainstem is the red nucleus |
|
Definition
|
|
Term
| where do rubrospinal axons project |
|
Definition
| from red nucleus to cervical spinal cord: lateral regions of ventral horn and intermediate gray matter |
|
|
Term
| what muscles does the rubrospinal tract influence |
|
Definition
| arm and shoulder muscles, mostly flexors |
|
|
Term
| is the rubrospinal tract as well developed in humans as in other mammals |
|
Definition
| no, we don't want our hands to have to do the same things. |
|
|
Term
| in humans, what is the rubrospinal tract probably a part of |
|
Definition
|
|
Term
| what are the 3 medial brainstem pathways |
|
Definition
| vestibulospinal, reticulospnial, colliculospinal |
|
|
Term
| what is the lateral brainstem pathway |
|
Definition
|
|
Term
| what do medial brainstem pathways influence |
|
Definition
| motor neurons in the medial portion of the ventral hron |
|
|
Term
| what does the lateral brainstem pahtway/ruborspinal tract do |
|
Definition
|
|
Term
| where are the umns that initiate complex voluntary movements |
|
Definition
|
|
Term
| in what part of the cerebral cortex are UMNs located |
|
Definition
|
|
Term
| from where do the motor cortical areas receive regulatory input |
|
Definition
| basal ganglia, cerebellum, sensory regions of the parietal lobes |
|
|
Term
| what do the cortical UMNs do |
|
Definition
| mediate planning and initiation of a complex sequence of voluntary movements |
|
|
Term
| what are the 2 parts of the motor cortex |
|
Definition
| primary and premotor cortices |
|
|
Term
| where is the primary motor cortex |
|
Definition
|
|
Term
| what is the brodmann's area of the primary motor cortex |
|
Definition
|
|
Term
| in what layer of the primary motor cortex are the cell bodies of the UMNs |
|
Definition
|
|
Term
| what are the names of the cells of the cell bodies of the UMNs in layer V of the primary motor cortex |
|
Definition
|
|
Term
|
Definition
|
|
Term
| what is the responsibility of the primary motor cortex |
|
Definition
| execution of motor function |
|
|
Term
| where is the premotor cortex |
|
Definition
| just anterior to the primary motor cortex |
|
|
Term
| what is the responsibility of the premotor cortex |
|
Definition
| planning and selecting movements |
|
|
Term
| what are the 2 pathways of the primary motor cortex |
|
Definition
| corticospinal, corticobulbar |
|
|
Term
| what are the corticospinal tracts |
|
Definition
| axons of the pyramidal cells in layer V that descend and synapse on LMNs and interneurons in the spinal cord |
|
|
Term
| what are corticobulmbar tracts |
|
Definition
| axons of the pyramidal cells in layer V that descend and synapse on LMNs of the cranial nerve nuclei |
|
|
Term
| in the somatotopic representation of the primary motor cortex, where are the toes |
|
Definition
|
|
Term
| in the somatotopic representation of the primary motor cortex, where is the head |
|
Definition
|
|
Term
| in what areas of the body do corticospinal tracts initiate movements |
|
Definition
|
|
Term
| in what areas of the body do corticobulbar tracts initiate movements |
|
Definition
|
|
Term
| do corticospinal tracts originate medially or laterally in the cortex |
|
Definition
|
|
Term
| do corticobulbar tracts initate medially or laterally in the cortex |
|
Definition
|
|
Term
| what is the first step of the path of the corticospinal tract after its formation from pyramidal cells in layer 5 of the primary motor cortex |
|
Definition
| axons of the pyramidal cells go through the internal capusle |
|
|
Term
| what does the corticospinal tract do after going through the internal capsule |
|
Definition
| continue through the midbrain cerebral peduncles and then onto the pons |
|
|
Term
| what do the corticospinal tracts do when they reach the medulla |
|
Definition
| continue through via the pyramids |
|
|
Term
| where do most corticospinal axons cross |
|
Definition
|
|
Term
| what is formed by the corticospinal tracts that cross in the caudal medulla |
|
Definition
| lateral corticospinal tracts |
|
|
Term
| what do the lateral corticospinal tracts do |
|
Definition
| synapse on alpha motor neurons in the lateral portion of the ventral horn |
|
|
Term
| what happens to the corticospinal tracts that do not cross to the other side in the caudal medulla |
|
Definition
| they enter the cord ipsilaterally and form the ventral corticospinal tract |
|
|
Term
| what is the path of the corticospinal tract after its formation from pyramidal cells in layer 5 of the primary motor cortex all the way through synapse on alpha motor neurons in the lateral portion of the ventral horn |
|
Definition
| axons travel through the internal capsule => axons travel through cerebral peduncles => axons travel through pyramids of medulla => majority of axons cross in the caudal medulla to form lateral corticospinal tracts which synapse on alpha motor neurons in the lateral portion of the ventral horn |
|
|
Term
| about what percentage of the original corticospinal tracts that came from the pyramid cells will remain ipsilateral in the cord and form the ventral corticospinal tract |
|
Definition
|
|
Term
| what are lateral corticospinals involved in |
|
Definition
|
|
Term
| what do ventral corticospinals allow |
|
Definition
| voluntary contraction of trunk muscles |
|
|
Term
| what do a small number of ventral corticospinal tracts do |
|
Definition
| cross the midline/commissure to terminate on contralateral LMNs |
|
|
Term
| describe the lateral corticospinal tracts: do they cross? Where do they synapse? What muscles do they influence? |
|
Definition
| motor pathways that cross and then synapse on lateral portions of the ventral horn to influence distal limb muscles |
|
|
Term
| describe the ventral corticospinal tracts: do they cross? Where do they synapse? What muscles do they influence? |
|
Definition
| motor pathways that mostly remain ipsilateral in the spinal cord and then synapse on medial portions of the ventral horn to influence axial and proximal muscles |
|
|
Term
| what are corticobulmbar tracts |
|
Definition
| UMN axons that originate in the motor cortex and synapse on LMNs in cranial nerve nuclei |
|
|
Term
| what are bilateral UMN projections |
|
Definition
| projections to cranial nerve nuclei from corticobulbar axons from both the R and L side of the brain |
|
|
Term
| do all cranial nerves receive bilateral projections |
|
Definition
|
|
Term
| does CN V receive bilateral projections from R and L corticobulbar tracts |
|
Definition
|
|
Term
| when cranial nerve nuclei do not receive bilateral projections, do they receive ipsilateral or contralateral projections |
|
Definition
|
|
Term
| does CN XII receive bilateral or contralateral projections of corticobulbar axons |
|
Definition
|
|
Term
| where in the brainstem is the facial motor nucleus |
|
Definition
|
|
Term
| why is the facial motor nucleus special |
|
Definition
| because its nucleus is divided into an upper and lower nuclei |
|
|
Term
| what does the upper facial motor nucleus control |
|
Definition
|
|
Term
| what does the lower facial nucleus control |
|
Definition
|
|
Term
| does the upper facial nucleus receive bilateral or contralateral projections of corticobulbar tracts |
|
Definition
|
|
Term
| does the lower facila motor nucleus reeive bilateral or contralateral projections from the motor cortex |
|
Definition
|
|
Term
| is Bell's palsy a lesion of UMN or LMN |
|
Definition
|
|
Term
| if you have a stroke/trauma to the right motor cortex, how will the face be affected |
|
Definition
| upper left facial muscles will work, but lower left facial muscles will not work normally |
|
|
Term
| what are upper motor neuron syndromes |
|
Definition
| results from damage to descending UMN pathways |
|
|
Term
| why is upper motor neuron syndrome a common injury |
|
Definition
| because of the large amount of cortex occupied by the motor area AND because the UMN pathways go a long way from the cortex to the spinal cord |
|
|
Term
| what are the results of acute damage to the motor cortex and/or descending axons in the internal capsule (UMN syndrome) |
|
Definition
| immediate flaccidity and hypotonia of muscles on contralateral side of body |
|
|
Term
| if you've had damage to your R motor cortex and I raise your L arm and let go, what will happen |
|
Definition
| it will drop down passively |
|
|
Term
| what is the result of acute motor cortex/UMN damage on reflexes |
|
Definition
|
|
Term
| what do we call the acute period of UMN injury |
|
Definition
|
|
Term
| how does the spinal cord react to UMN syndrome after a few days |
|
Definition
| spinal cord circuits regain much of their function |
|
|
Term
| what consistent pattern of symptoms emerge a few days after UMN syndrome/spinal shock |
|
Definition
| Babinski, spasticity, loss of fine movements, weakness |
|
|
Term
|
Definition
| extension and fanning of the toes |
|
|
Term
| what is a normal babinski reflex |
|
Definition
|
|
Term
| what 3 things does spasticity include |
|
Definition
| hypertonia, hyperreflexia, clonus |
|
|
Term
|
Definition
|
|
Term
|
Definition
| hyperactive stretch reflex |
|
|
Term
|
Definition
| oscillatory motor response to stretch |
|
|
Term
| why does spasticity occur in UMN syndrome |
|
Definition
| due to increase in gain of the stretch reflex resulting from loss of descending inhibition |
|
|
Term
| why do you lose the ability to perform fine movements in UMN syndrome |
|
Definition
| loss of corticospinal tract |
|
|
Term
| why do babies get babinski |
|
Definition
| their UMNs are not get myelinated |
|
|
Term
| what are the symptoms of LMN dyndrome |
|
Definition
| weakness/paralysis, decreased superficial reflexes, hypoactive deep reflexes, decreased tone, fasciculations and fibrillations, muscle atrophy |
|
|
Term
| compare the motor cortex's functional organization to its sensory organization |
|
Definition
| similarly disproportionate |
|
|
Term
| what, in the 60's and 70's, allowed more detailed understanding of the functional motor maps of the cortex |
|
Definition
| intracoritical microstimulation |
|
|
Term
| how does intracortical microstimulation work |
|
Definition
| by passing current through a microelectrode inserted into the cortex, UMNs in layer V can be stimulated focally and monitored with recordings of electrical activity. |
|
|
Term
| what does intracoritical microstimulation show |
|
Definition
| small currents initiate excitation of several muscles, suggesting that organized movements rather than individual muscles are represented in the motor bmaps |
|
|
Term
| what are the 2 parts of the premotor cortex |
|
Definition
| lateral premotor cortex, medial premotor cortex |
|
|
Term
| what is another term for lateral premotor cortex |
|
Definition
|
|
Term
| what is another term for medial premotor cortex |
|
Definition
| SMA: supplemental motor area |
|
|
Term
| what muslces does the PMA/premotor area/lateral premotor cortex target |
|
Definition
|
|
Term
| what muscles does the SMA/supplemental motor area/medial premotor cortex target |
|
Definition
|
|
Term
| is the SMA or PMA more tuned to skilled movements |
|
Definition
|
|
Term
| do premotor cortices contribute to motor functions through direct or indirect connections |
|
Definition
| direct connections to the primary motor cortex |
|
|
Term
| what percentage of corticospinal tracts that project from the primary motor cortex to the spinal cord first originated in the premotor cortex |
|
Definition
|
|
Term
| what information do neurons in the lateral premotor cortex encode |
|
Definition
| intention to perform a movement as well as selection of movements |
|
|
Term
| what does the lateral premotor cortex use to select movements |
|
Definition
|
|
Term
| what information do neurons in the medial premotor cortex encode |
|
Definition
|
|
Term
| what does the medial premotor cortex use to select movements |
|
Definition
|
|
Term
| from which part of the premotor cortex would neurons fire based on memory |
|
Definition
|
|
Term
| from which part of the premotor cortex would neurons fire based on sight of a red light |
|
Definition
|
|
