Motor Systems Flashcards by Julia Nauman

High motor neurons

Function: Strategy
Structures: association areas of neocortex, basal ganglia

From brain to spinal cord

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Middle motor neurons

Function: Tactics
Structures: motor cortex,cerebellum

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Low motor neurons

Function: execution
Strategy: brain stem, spinal cord

Exit spinal cord to innervated muscles

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Axial muscles

movement of trunk

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Proximal-gridle muscles:

shoulder, elbow, pelvis, knee

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Distal muscles

hands, feet, digits (fingers/toes)

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Smooth muscle- enteric

innervated by nerve fibers from the autonomic nervous system (ex: digestion and blood pressure)

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Striated muscles

cardiac (heart) and skeletal

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skeletal muscles

bulk of muscle mass- mediates movements, facial expression etc.

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Amyotrophic lateral sclerosis- ALS (lou Gehrig’s)

muscle weakness/atrophy, slow deterioration of alpha motor neurons due to loss of superoxide dismutase, meaning they can’t break down free radials.

Excitotoxicity: glutamate overstimulation, treatment targets release of glutamate.

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Muscular Dystrophy

Progressive weakness and muscle deterioration= genetic loss of dystrophin

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Myasthenia Gravis

Autoimmune disease- nAChRs

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Cortico/Rubrospinal tract functions.

Transmission of commands for skilled movements. Corrections of motor patterns generated by spinal cord.

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Antigravity muscles are mainly _____ and ______

Paravertebral extensors

Proximal extensor arms of legs

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Recticulospinal functions

Activate spinal motor programs for steeping and other stereotyped movements
upright body posture

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Corticospinal tract crosses in ____. It controls distal musculature (extensors). What happens if it is lesion?

Crosses in pyramids.

If lesioned, can’t move limbs independently, voluntary movements are slow and inaccurate. Rubrospinal may compensate.

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Rubrospinal Tract receives central input from ____ and crosses in the ____.

Cortex

Pons

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Lateral Pathways control what?

Voluntary movements of distal musculature- primarily to flexors/extensors?

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Ventral pathway functions

postural musculature. Originate in brainstem, use sensory info about balance and position to reflexively maintain balance and posture

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Vestibulospinal pathway

Vestibular nucleus/labyrinth. Cranial Nerve 8. Control neck/back muscles down lumbar to facilitate extensor muscles of legs . Cerebellar inputs, no cortical.

Generation of tonic activity in antigravity muscles

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Tectospinal

Originate in superior colliculus (tectum). head/neck posture and movement

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Area 4- primary motor cortex M1

Wilder penfield

Stimulation leads to movement/twitching in arm/limb, motor output.

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Area 6: PMA

What does it do, and where does it project to?

Premotor area: skill voluntary movement (sensory-motor associations). Projects to reticulospinal/proximal muscles.

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Area 6: Supplementary motor area (SMA).

Also, what do lesion result in?

Sequences and bimanual coordination innervation to distal muscles.

Apraxia- inability to perform skilled movements.

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What area has the lowest threshold for elicitation of the movements by electrical stimulation?

Area 4

Activity in M1 motor neurons encodes what two things?

Force and direction

What are the dopaminergic inputs that degenerate during Parkinson's?

Those to the substantia nigra pars compacta= striatum

What disease results in HYPOkinesia (decreased movement) by degeneration of substantia nigra (pars compacta) resulting in tonic inhibition to thalamus?

Parkinson's (more inhibition)

Bradykinesia

Slow movements (substantia nigra)

Akinesia

Difficulty in initiating willed movements (substantia nigra)

Rigidity

increased muscle tone (substantia nigra)

Tremors at rest

Subtantia nigra

What disease results in Hyperkinesia because of loss of neurons caudate-putamen and GP and loss of inhibitory input to thalamus?

Huntington's (less inhibition) Also dementia, personality changes

Dyskinesias

Abnormal, purposeless movements | Caudate-putamen, and GP

Chorea

spontaneous uncontrolled movements (Caudate-putamen, GP)

Ballism (or more common, hemiballism)

wild flinging of extremities., hyperkinesia. Damage to subthalamic nucleus, loss of excitatory input to GP, facilitation of VLo. Did inhibition

Hyperkinesia means (increased or decreased) BG output?

Decreased

List that Basal Ganglia Planned movements pathway

input to thalamus (VLo) then to Area 6

List Cerebellum coordinated motor function pathway

input to thalamus (VLc) then to area 4, then project to layer 5, betz cells

Cerebellum inputs

spinal cord/brain stem, proprioceptive inputs from cerebral cortex to coordinate motor outputs

Cerebellum outputs

thalamus, brainstem, spinal cord.

Cerebellum lesion ataxia

inaccurate, uncoordinated movements

Cerebellum functions

Motor Learning (learning motor sequences, multi-joint movements) Coordinate movement (movement/balance)

Cerebellum Excitatory input from _____ and inhibitory output to _____.

Inferior olive Deep Nuclei

Cerebellum: Vestibulocerebellum. Function and deep nucleus

Head/body in space, equilibrium, eye orienting Fastigial nucleus

Cerebellum: Spinocerebellum: Function and deep nucleus

Control axial musculature through fastigial and vernal cortex. Limb musculature through interposed nuclei and paravernal cortex Interposed (globose and emboliform) deep nuclei

Cerebellum: Pontocerebellum (nocerebellum) Lateral

Precision and timing of movements of upper extremities (arms/legs), lateral hemispheres. Dentate nucleus

Alpha motor neuron inputs

Spinal innervation Sensory input from muscles spindles Input from upper motor neurons in the brain

Muscle spindles function? (La sensory neurons)

Sense muscles length In parallel Largest and fastest axons

Gamma neurons ___intrafusiak fibers when extrafusial shorten

Contract

Gamma neurons _____ la activity

Increase

Myotactic reflex

Knee jerk, vibration, causes extension La axon ---> alpha motor neuron

Reverse myotactic reflex

Prevents muscle overload, keeps tension in optimal range LB axon ---> inhibitory interneuron, which inhibits alpha neuron. Golgi neurons inhibit Lowe motor neurons

Reciprocal inhibition.

Contract one muscle with la axon, relax antagonistic muscles

Flexor reflex

Withdraw from pain

Crossed extensor reflex

Withdrawal of antigravity extensor muscles of leg opposite pain

Function of golgi tendon organ

Strain gauge, monitors muscles tension/congregation. Synapses in central horn. Lb axon active with alpha motor neurons.

Lesions in vestibulocerebellum

Unsteady Drunk Fall

Lesions in ponticerebellum

Hypotonia, ataxia Intention tremor (when you reach for stuff)

In granular layer, ______ are excitatory, _______ are inhibitory

Granule Golgi

Mossy fibers send glutamate to

Golgi and granule

Climbing fibers are excitatory, and aspartate synapse on _____ cells

Purkinje

Multilayered fibers are

Inhibitory