Motor Systems I-III Flashcards by t g

location of proximal vs distal and flexor vs extensor interneurons in the ventral horn

proximal motor neurons are medial and dorsal, distal motor neurons are lateral and more ventral

extensors are medial and ventral, flexors are lateral and dorsal

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location of pximal vs distal and flexor vs extensor interneurons in the ventral horn

proximal motor neurons are medial and dorsal, distal motor neurons are lateral and more ventral

extensors are medial and ventral, flexors are lateral and dorsal

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where in the spinal cord are descending tracts located?

in the white matter adjacent to the relevant motoneuron pools they control

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where does proprioceptive input originate? Where does the cutaneous input to that cortical column originate?

in the distal joint involved in the movement of the muscle which that column influences

the cutaneous input to that cortical column originates in the skin region lying in the path of limb movement produced by those muscle contracting

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word to describe how the precentral motor cortex is organized

somatotopically

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these have tight input-output coupling

cortical columns

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inputs from proprioception and cutaneous input to a column travel through

thalamic VA-VL nuclei

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path of cortical reflex

retina, LGN, visual cortex, PIT, AIT, prefrontal cortex, premotor cortex

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path of visuo-motor reflex

retina, LGN, visual cortex, PIT, AIT, prefrontal cortex, premotor cortex, motor cortex, to spinal cord, to finger muscle

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percentage of the corticospinal tract that arises in the precentral and postcentral cortex

90%

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what is the 80% of corticospinal tract that crosses at the end of the pyramids?

what is the 20% of the corticospinal tract that remains ipsilateral?

lateral corticospinal tract

anterior corticospinal tract

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corticospinal system pathway in brain and brainstem from top to bottom

corona radiata, internal capsule, cerebral peduncle, basis pontis, medullary pyramids, medullary decussation

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how are the sacral, lumbar, thoracic, and cervical neurons arranged in the spinal cord?

medial to lateral: C, T, L, S

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what type of control for pathways controlling axial and proximal muscles for posture

tonically

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control for pathways controlling distal muscles for discrete movements

phasically

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tonic systems include

pontine reticulospinal, vestibulospinal, tectospinal

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phasic systems include

corticospinal, rubrospinal, medullary reticulospinal

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medullary reticulospinal tract vs pontine reticulospinal tract: which is excitatory, which is inhibitory? which turns on when dreaming?

medullary reticulospinal tract is inhibitory/turns on when dreaming (paralysis)

pontine reticulospinal tract is excitatory

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where do pontine and medullary reticulospinal tracts end?

pontine ends at the level of C8 in the most medial aspect of the ipsilateral ventral spinal cord

medullary ends at level of C8 in the most anterior aspect of the ipsilateral spinal cord

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what do the vestibulospinal tracts terminate on?

alpha motor neurons (don’t forget alpha-gamma linkage)

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origin of tectospinal tract

superior colliculus

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tract used for movement of neck and following an object with eyes while turning head

tectospinal tract

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where does tectospinal tract terminate?

extensor interneurons in upper cervical region

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where does lateral corticospinal terminate?

anterior corticospinal?

mostly flexors, somewhat on extensors, interneuron pools

extensor interneurons

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termination sites of rubrospinal tract

flexor alpha motor neurons (cervical), extensor alpha motor neurons

termination site of medullary reticulospinal tract termination site of pontine reticulospinal tract

flexor and extensor interneurons extensor interneurons

termination of vestibulospinal tract

extensor alpha motor neurons and interneurons

what part of the brain inhibits rubrospinal tract, pontine reticulospinal tract, and excites the medullary reticulospinal tract?

cortex (areas 4, 6, 1, 2, 3)

so if there is a stroke in the cortex, and it no longer inhibits pontine reticulospinal tract? what about it its not inhibiting rubrospinal tract?

toes would point arms would be flexed

if after a stroke, a patient's arms and legs are extended, what has been eliminated?

the cortex inhibiting the pontine reticulospinal tract

if after a stroke, a patient's extremities are flaccid, what has been eliminated?

the cortex exciting the medullary reticulospinal tract

what comprises the striatum?

caudate nucleus and putamen

interneurons from striatum go on to control what 2 areas?

external and internal globus pallidus substantia nigra

main input to the striatum?

cortex (mostly glutamate)

striatum also has inputs from..

central medial nucleus of thalamus, VA, VL

VA, VL, CM controls tone of the

cerebellum

substantia nigra has this massive projection into the striatum

dopamine

only midline nucleus in the medulla, midbrain, pons; where does it project? is it inhibitory or excitatory?; what catecholamine does it carry?

raphe nuclei cortex and spinal cord mostly inhibitory serotonin

4 major inputs to the striatum

cortex raphe nuclei VA-VL-CM internal/external GP + substantia nigra

cortex inputs to the striatum, namely topographic and thalamic, release what NT?

glutamate

what regulates output of the striatum?

subthalamic nucleus and external pallidum

basal ganglia outputs from the internal pallidum and substantia nigra travel here by ascending, and here by descending

thalamus midbrain

functions of the basal ganglia

prep for movement organization of sequences of movements learning of hierarchically organized movements sensory and motor modulation

functions of the cerebellum

unconscious control of movement regulation of rapid (preprogrammed) movement posture, muscle tone, equilibrium

the floc-nod lobe part of the cerebellum the anterior lobe of cerebellum the posterior lobe of the cerebellum

archicerebellum paleocerebellum neocerebellum

name the components of the path from spinal cerebellar tracts to the cerebellum?

spinl cord, mossy fibers, granule cells bifurcate and activate a row of Purkinje cells

where do climbing fibers in the cerebellum arise from?

inferior olivary nucleus

to inhibit the glomerulus, what has to be activated?

Golgi cell

name the components of the path from spinal cerebellar tracts to the cerebellum?

spinal cord, through inf peduncle, mossy fibers, granule cells bifurcate and activate a row of Purkinje cells

where do mossy fibers terminate?

on glomeruli, containing granule cell dendrites and Golgi cell axons

what do granule cell axons split into? where do they synapse?

parallel fibers synapse on Purkinje, Golgi, and basket cell dendrites

where do climbing fibers synapse?

on Purkinje cell bodies

where do Purkinje cell axons travel to?

intracerebellar nuclei and pons

all inputs (mossy fibers, climbing fibers) at the cerebellum are excitatory or inhibitory?

excitatory

all outputs (purkinje cell axons) of the cerebellum are excitatory or inhibitory?

inhibitory on intracerebellar nuclei and pons

axons of intracerebellar nuclei are excitatory or inhibitory?

excitatory

easiest way to temporarily damage the cerebellar cortex

alcohol- acts on granule cells in cortex

biggest input to cerebellum

pontine nuclei (not spinal cord)

biggest output of the cerebellum

SCP-Dentato-rubro-thalamic

describe the path of the SCP-dentate-rubro-thalamic tract; what does it generate?

dentate, red nucleus descends, crosses immediately, terminates on rubrospinal tract to generate flexion

what role does the thalamus lay in cerebellar output?

thalamus deciphers what cerebellum says is happening, puts it together with what basal ganglia has decided, and then cortex and lat corticospinal tract carry out the next move

how is basic rhythmic pattern generated in the spinal cord?

by central pattern generators

what tract informs cerebellum about actual muscle activity? what tract informs cerebellum about intended pattern?

dorsal spinocerebellar tract ventral spinocerebellar tract

what causes intention tremor?

damage to the hemisphere of the cerebellum or the dentate in particular

damage to the caudate nucleus causes

chorea (jerky involuntary movements associated with Huntington's)

decorticate rigidity vs decerebrate ridigity

decorticate: flaccidity that quickly becomes spastic- flexion of arms, extension of legs decerebrate: marked extension of arms and legs, Babinski, hyperreflexia