Motor System + Basal Ganglia Flashcards
what are the two locations for lower motor neurons?
ventral horn of SC and cranial nerve motor nuclei of brainstem
what part of brain houses nuclei of lower motor neurons for the cranial nerves?
brainstem
are lower motor neurons the final common pathway for voluntary, involuntary or both?
Both movements
what is the corticobulbar tract?
runs from cortex and synapses in brainstem to lead to innervation of cranial nerves
early upper motor neuron injury leads to what?
paralysis/weakness
late upper motor neuron syndrome leads to what?
babinski sign
muscle spasticity
hyperactive reflexes
no muscle atrophy
lower motor neuron syndrome leads to what clinically?
hyporeflexive
flaccid paralysis
atrophy
fibrillations/fasciculation
what are fibrillations/fasciculations?
spontaneous muscle twitches
what region of the brain is important for movement inhibition and coordinates with the motor tracts?
basal ganglia
what region of the brain is important for balance and coordination and coordinates with the motor tracts?
cerebellum
name the five parts of the basal ganglia
caudate nucleus putamen globus pallidus substantis nigra subthalamic nucleus
where does the basal ganglia receive input?
cortex
where does the basal ganglia output go?
thalamus
what makes up the striatum in the basal ganglia?
caudate and putamen
where is the caudate located in coronal cross section of brain?
just lateral to the lateral ventricles
the caudate and putamen make up what in the basal ganglia?
striatum
the cortex stimulates what in the basal ganglia to initiate response?
striatum
what Nt does the cortex use to stimulate the striatum in the basal ganglia?
glutamate
what are the two pathways in the basal ganglia?
indirect and direct
the goal of the direct pathway of the basal ganglia is what?
to allow movement
the goal of the indirect pathway of the basal ganglia is what?
to inhibit movement
what is the baseline action of the thalamus?
to inhibit the motor function at rest
what is the baseline action of the globus pallidus internus and pars reticulatum on the thalamus?
to increase thalamic inhibition of the cortex
what are the two parts of the globus pallidus?
globus pallidus internus
globus pallidus externus
what are the two parts of the substantia nigra in the basal ganglis?
pars reticulata
pars compacta
what does the striatum do in the direct basal ganglia pathway when it is activated?
inactivates the globus pallidus internus and pars reticulata
what Nt does the striatum use in the direct pathway to inhibit the pars reticulata and the globus pallidus internus?
GABA
in the direct pathway, with the inhibition of the globus pallidus internus and the pars reticulata, what does this allow for from the thalamus?
thalamus is no longer inhibited by these and can increase motor movement in the cortex
what is the modifier of the indirect and direct pathway of the basal ganglia?
cortex stimulates the pars compacta to dump dopamine on the striatum of the basal ganglia
what is the dopamine receptor used by the direct pathway in the basal ganglia on the striatum?
D1
what is the dopamine receptor used by the indirect pathway in the basal ganglia on the striatum?
D2
once the striatum is activated by glutamate in the indirect pathway of the basal ganglia, what occurs?
inhibition of the globus pallidus externus using GABA
what Nt does the indirect pathway use to inhibit globus pallidus externus?
GABA
what is the normal function of the globus pallidus externus?
to inhibit the subthalamic nucleus
what is the normal role of the subthalamic nucleus?
to stimulate the globus pallidus internus
when the indirect pathway of the basal ganglia inhibits the globus pallidus externus what happens to the subthalamic nucleus?
it is no longer inhibited and can lead to more stimulation of the globus pallidus internus
more activation of the globus pallidus internus by the decreased inhibition of the subthalamic nuclei in the indirect pathway of the basal ganglia leads to what in the thalamus?
more inhibition of the thalamus
does the D2 receptor in the striatum that receives input from the pars compacta lead to stimulation or inhibition of the indirect pathway?
inhibition of the indirect pathway
