Lecture 8 Motor 2 Flashcards
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
What makes up the cerebral cortex?
Primary motor cortex 4
Premotor cortex 6
Supplementary cortex 6
what is the function of the premotor cortex?
plan movements based on sensory and visual cues
what is the function of the supplementary motor area
retrieves and coordinates memorized motor sequences
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
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
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
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
what happens if cerebellum is removed?
body movements become highly abnormal
what are the 2 hemispheres separated by?
what are they divided into?
vermis
intermediate and lateral zones
what are the 3 lobes?
anterior
posterior
flocculonodular
what is the vermis the location for?
muscle movements of axial body, neck, shoulders, hips
what is the intermediate zone location of?
muscle contractions of the distal upper and lower limbs, hands, feet, fingers, toes
what is the lateral zone location for?
with the cerebral cortex with planning of sequential motor movements
what does the cortex consist of?
transversely arranged narrow gyri called folia
what are the types intracerebellar nuclei?
Dentate
Emboliform
Globose
Fastigial
DEG lesions lead to what?
where do these project to?
related to what?
extremity ataxia
red nucleus
limb musculature and fine movements
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
what are granular cells?
inhibitory or excitatory?
axons from parallel fibers in cortex
excitatory
what are golgi cells?
EX or INHIB
project from parallel fibers to granular cell bodies
inhibitory
what are basket cells?
ex or in
project from parallel fibers to purkinje axon hillock
Inhibitory
what are stellate cells?
ex or in
project from parallel fibers to Purkinje dendrites
Inhibitory
What are 4 features of Purkinje cells?
have extensive dendrite branching
receive input from parallel fibers
project to intracerebellar nuclei (-)
ONLY output from cortex
where is each functional unit centered?
on a Purkinje cell and corr. deep nuclear cell
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?
- help the cortex execute subconscious but learned patterns of movement
- 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?
- maintenance of axial tone of the body for standing
- continuous modification of the degrees of tone in the different muscles in response to info. from the vestib apparatuses to maintain body equilibrium
