22 – Motor Control I Flashcards
Lower motor neuron definition:
-motor neurons within CNS that have axons extending into PNS to innervate targets
>brainstem
>CN (except 1, 2, 8)
>SC
LMN cell body and axon location:
-cell body: CNS
-axon: PNS
Upper motor neuron definition:
-motor neurons that synapse on other UMNs or LMNs to control movements or functions, which are located in:
>cerebrum
>midbrain
>pons
>medulla
UMN cell body and axon location:
-cell body: CNS
-axon: CNS
What is the ultimate function of the NS?
-RESPOND to external stimuli
>initiates and completes motor movements
UMN initiate:
-motor movements
>axon extend from brain through brain + SC to synapse with LMN in brainstem + SC
*damage=paresis and paralysis (loss of voluntary motor control)
Brainstem UMNs:
-midbrain
-pons
-medulla
What are the 3 nuclei that are important for UMN movements?
-red nucleus
-vestibular nucleus
-reticular nuclei
Red nucleus ‘pathway’:
-midbrain
-brainstem
-SC (dorsal aspect of lateral funiculus)
What is the name of the red nucleus spinal tracts?
-rubrospinal tracts
*dorsal aspect of lateral funiculus
Red nucleus:
-located in midbrain
-paired structure
-axons decussate (crossover) immediately in midbrain
>have contralateral effects
What are the rubrospinal tracts (red nucleus) involved in with regard to their motor neurons?
-activate FLEXOR muscles
-inhibit extensor muscles
Vestibular nucleus:
-lives in medulla
*does NOT cross over
>ipsilateral effects
What is the name of the vestibular nucleus spinal tracts?
-vestibulospinal tracts
What are the vestibulospinal tracts (vestibular nucleus) involved in with regard to their motor neurons?
-inhibits the red nucleus
>activates extensors
>inhibits flexors