Lecture 8 Motor 2 Flashcards by Alex Hamidi

what are the functions of the primary motor cortex?

signals motor neurons to contract skeletal muscle fibers
signals via the corticospinal tract
execution done by cerbellum and basal nuclei

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What makes up the cerebral cortex?

Primary motor cortex 4
Premotor cortex 6
Supplementary cortex 6

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what is the function of the premotor cortex?

plan movements based on sensory and visual cues

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what is the function of the supplementary motor area

retrieves and coordinates memorized motor sequences

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what are the motor cortex functions?

activating signals to spinal cord
issues sequential and parallel commands
cortical patters are usually complex, can be learned
patterns are hereditary and hard wired

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what does the cerebellum play a major role in?

timing of motor activities and in rapid, smooth progression from one muscle movement to the next

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list some features of the cerebellum

learns from mistakes
not essential for locomotion
compares actual and intended movements
works with spinal cord to enhance stretch reflex
works with brain stem to make postural movements

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what does the basal nuclei do?

plans and controls complex patterns of muscle movement, controlling relative intensities of the separate movements, directions and sequencing

helps plan parallel seq patterns

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what happens if cerebellum is removed?

body movements become highly abnormal

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what are the 2 hemispheres separated by?

what are they divided into?

vermis

intermediate and lateral zones

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what are the 3 lobes?

anterior
posterior
flocculonodular

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what is the vermis the location for?

muscle movements of axial body, neck, shoulders, hips

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what is the intermediate zone location of?

muscle contractions of the distal upper and lower limbs, hands, feet, fingers, toes

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what is the lateral zone location for?

with the cerebral cortex with planning of sequential motor movements

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what does the cortex consist of?

transversely arranged narrow gyri called folia

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what are the types intracerebellar nuclei?

Dentate
Emboliform
Globose
Fastigial

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DEG lesions lead to what?
where do these project to?
related to what?

extremity ataxia
red nucleus
limb musculature and fine movements

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Fastigial lesions lead to what?
fibers project to where?
related to what?

trunk ataxia
reticular formation and vestibular nuclei
postural activity and limb movements via reticulospinal and vestibulospinal tracts

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what are granular cells?

inhibitory or excitatory?

axons from parallel fibers in cortex

excitatory

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what are golgi cells?

EX or INHIB

project from parallel fibers to granular cell bodies

inhibitory

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what are basket cells?

ex or in

project from parallel fibers to purkinje axon hillock

Inhibitory

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what are stellate cells?

ex or in

project from parallel fibers to Purkinje dendrites

Inhibitory

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What are 4 features of Purkinje cells?

have extensive dendrite branching
receive input from parallel fibers
project to intracerebellar nuclei (-)
ONLY output from cortex

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where is each functional unit centered?

on a Purkinje cell and corr. deep nuclear cell

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what is the output from a functional unit from?

deep nuclear cell

where do climbing fibers originate from?

inferior olives

where do mossy fibers send signals to?

excitatory collateral to deep nuclear cells and then synapse in granular layer with thousands of granule cells

Direct stimulation by climbing and mossy fibers does what?

excites deep nuclear cells

what inhibits deep nuclear cells?

Purkinje cell signals

what are the 3 levels of nervous system control involving the cerebellum to coordinate motor function?

vestibulocerbellum spinocerebellum cerebrocerebellum

what does the vestibulocerebellum consist of? where does it receive fibers from? where does it send output to?

flocculonodular and vermis vestibular and oculomotor systems vestibular system

loss of flocculonodular lobes leads to what?

extreme disturbance of equilibrium and postural movements

what happens when the cerebellum is removed?

movements are slow to develop force is weak movements slow to turn off

what does the spinocerebellum consist of? | where does it receive info from?

vermis and intermediate zones | motor cortex and red nucleus, feedback info from periphery

the spinocerebellum compares two sources of info and sends corrections to where?

motor cortex via thalamus | magnocellular portion of red nucleus

what does the cerebrocerebellum consist of? | what does it receive?

lateral parts of hemispheres | corticopontocerebellar projections

what is the cereberocerbellum involved in? | what is it referred to as?

coordination of skilled movements and speech | motor imagery

what is dysmetria

lack of coordination of movement typified by overshoot or undershoot of intended position with hand, leg, eye inability to judge distance or scale

what is ataxia?

uncoordinated movements

what is past pointing

manifestation of dysmetria | person moves finger past point of intention in absence of cerebellum

what is dysdiadochokinesia?

inability to perform rapid alternating movements

what is dysarthria?

failure of progression in talking, speech jumbled

what is cerebellar nystagmus?

tremor of eyeballs when fixating on one side

what is hypotonia

low muscle tone, reduced muscle strength

what are the afferent tracks to the cerebellum?

``` corticoponto vestibulo reticulo spin (dorsal and ventral) olivo ```

what is the pathway of the corticoponto

motor and premotor/somatosensory cortices --> pontine nuclei --> lateral divisions of cerebellum

where does the vestibulocerebellar terminate?

flocculonodular lobes

where does the reticulocerebellar terminate?

vermis

what tracts form the mossy fibers?

corticoponto, vestibulo, reticulo, spino

what is the pathway of dorsal spinocerebellar?

muscle spindles --> ipsilaterally in vermis and intermediate zones

what does the dorsal spino aprise the cerebellum of?

muscle contractions tension on spindles position and rates of body movement forces acting on body

where does the ventral spino terminate? it is excited by signals coming from where?

ipsilaterally and contralaterally cortex via cortico and rubro internal motor pattern generators

what does the ventral spino tell the cerebellum?

which motor signals have arrived at the anterior horns | feedback = efference copy ant horn motor drive

where do olivocerebellar neurons project from and to? what kind of spike signal is it?

inf. olivary nuclei to Purkinje cell dendrites (+) and to intracerebellar nuclei complex

Cerebelloreticular tract

Fastigial nuclei --> reticular nuclei in pons and medulla

Cerebellothalamocortical tract

DEG --> thalamus --> motor cortex

Cerebellorubral tract

DEG --> red nucleus

Cerebellovestibular tract

cerebellum --> vestibular nuclei

where do basal nuclei receive their input from? where do they return their output?

cerebral cortex cerebral cortex

what is the principal role of the basal nuclei?

work with the corticospinal system to control complex patterns of motor activity

what does the basal nuclei consist of paired?

``` CPGSS caudate putamen globus pallidus Substantia nigra subthalamic nucleus ```

what is the putamen circuit for? outline its pathway

subconscious execution of learned patterns of movement cerebral cortex --> putamen --> globus pallidus (external) --> thalamic relay center --> primary motor cortex

lesions in globus pallidus?

athetosis - writhing movements

lesions in subthalamus

hemiballismus - flailing, sudden movements entire limb

lesions in putamen

chorea - flicking movements hands face

lesions in substantia nigra

Parkinson's - rigidity, akinesia, tremors

what is the caudate circuit for? outline its pathway

cognitive planning of sequential and parallel motor patterns cerebral cortex --> caudate nucleus --> globus pallidus (internal) --> thalamic relay center --> premotor and supp. motor cortex

dopamine is inhibitory of what pathway?

substantia nigra --> caudate nucleus and putamen some dicks cum and pee

caudate nucleus and putamen --> globus pallidus and substantia nigra uses what neurotransmitter?

GABA (inhibitory) cpggs

Cortex --> caudate nucleus and putamen what neurotransmitter

Ach c a c

Multiple pathways from the brain stem uses which neurotransmitters?

NE, serotonin (inhibitory), encephalin brain ridin dat BENS

what is Parkinson's a result of?

destruction of pars compacta of substantia nigra that sends dopaminergic fibers to caudate nucleus and putamen

What are characteristics of Huntington's Disease

flicking movements of muscles distortional movements of body dementia motor dysfunction

what are abnormal movements probably caused by?

loss of GABA secreting neurons of caudate nucleus and putamen and Ach neurons in other brain parts

what are the 2 most important functions of the basal nuclei?

1. help the cortex execute subconscious but learned patterns of movement 2. help plan multiple parallel and sequential patterns of movement that the mind must put together to accomplish a purposeful task

what is agnosia? what lesion is it associated with?

inability to accurately perceive objects posterior parietal cortex

what 2 major functions are provided by the hindbrain for general motor control of the body?

1. maintenance of axial tone of the body for standing 2. continuous modification of the degrees of tone in the different muscles in response to info. from the vestib apparatuses to maintain body equilibrium