Motor Circuit Flashcards
What does the basal nuclei motor circuit manage?
- Movement selection and control
- Regulates muscle contraction, muscle force, and sequencing of movements.
Motor circuit regulates which UMNs are to be excited and which need to be inhibited to carry out the?
Desired movement and prevent unwanted movement
Motor circuit major outputs to the VA and VL nuclei of the?
Thalamus and rostral brainstem.
- Regulation of muscle tone
- No direct LMN connections
Motor circuit lesions cause an imbalance of facilitation and inhibition of?
Too much movement or too little movement not paraylsis.
Motor Circuit - Direct pathway overall -
Excitatory to movement = move more
Motor Circuit - Indirect pathway overall -
Inhibitory to movement = move less
Motor Circuit - Hyperdirect pathway overall -
Strong inhibition of movement
The hyperdirect pathway?
Stops movement in progress when a new movement is desired
The direct pathway?
facilitates specific desired movements
The indirect pathway?
prevents unwanted movements
Output nuclei are the nuclei that provide most of the output from the basal nuclei to other regions of the brain and brainstem. Output nuclei are the?
Globus pallidus internus
Substantia nigra pars reticularis
Output nuclei - T/F - The more active the output nuclei are the less overall movement there will be?
T
What three ways the output nuclei decrease overall movement. First way?
Inhibits the motor thalamus (VA and VL nuclei)
-Inhibiting the thalamus, the ability of the thalamus to activate the motor cortices is reduced, thus less excitation of UMNs in the descending motor pathways
What three ways the output nuclei decrease overall movement. Second way?
Inhibit the rostral brainstem
-Inhibiting the rostral brainstem, inhibition of the reticulospinal tracts to the trunk and girdle muscles is reduced and axial tone increases
What three ways the output nuclei decrease overall movement. Third way?
Inhibit the rostral brainstem
-Inhibiting the rostral brainstem, excitation of stepping pattern generators is reduced, decreasing initiation of gait
Motor circuit - balance between excitatory and inhibitory influences on the output nuclei determines the amount of?
movement
What are the two types of synapses?
Excitatory (generates EPSP)
Inhibitory (generates IPSP)
If one nucleus is prevented from inhibiting a second nucleus, the second nucleus is now said to be?
Disinhibited
-The type of synapse between these nuclei is still inhibitory.
A direct (GO) pathway starts at the ____ and ends at the ____?
putamen
output nuclei
Direct (GO) pathway overall ____ movement?
increases
Direct (GO) pathway - putamen wants to ____ the output nuclei?
inhibit
Direct (GO) pathway - (Putamen to Output nuclei) decreased activity of output nuclei leads to:
______ activity in corticospinal and corticobrainstem tracts increasing limb and face movements.
______ activity in reticulospinal tracts reducing trunk and girdle muscle tone.
increased
decreased
Direct (GO) pathway - (Putamen to Output nuclei) -
____ activity of output nuclei leads to:
- ______ activation of stepping pattern generator
- Together these changes leads to an overall ____ in movement.
Decreased
Increased
Increase
Indirect (no GO) pathway - starts in _____ and ends at the ____ passing through the ____ and the sutbthalamus nucleus along the way.
putamen
output nuclei
globus pallidus externus
