Lecture 5- motor control (Direct and indirect activation pathways;U Flashcards
What are the 3 stages of motor learning?
planning, programming, and execution
The corticobulbar tract is _______, whereas the corticospinal tract is ______.
Bilaterally; mostly contralateral
What is the pathway of the corticospinal tract?
Motor cortex –> UMN synapses with LMN; LMN sends signals down the spinal cord via spinal nerves —-> spinal nerves innervate the skeletal muscles
Where in the brain are the UMNs located?
in the motor cortex
Where in the brain are the LMNs located?
in the CNS
LMN axons leave the CNS through _______.
spinal nerves
The left ventral motor area is also known as
Broca’s area
The lateral corticospinal tract innervates ____
muscles in the limbs
The anterior corticospinal tract innervates _____
muscles of the trunk
In the lateral corticospinal tract, where do the UMN axons decussate?
at the caudal medulla or pyramids of the medulla
What areas of the brain does the motor impulses go through on the lateral corticospinal tract to innervate a muscle?
motor strip —- > UMN —> internal capsule—-> midbrain —-> pons —-> rostral medualla —- caudal medulla —-> LMN —– spinal cord
What is the purpose of the corticospinal tract?
it carries motor impulses from the pre-central gyrus to the skeletal muscles
What is the pathway of the anterior corticospinal tract that the motor impulses pass through?
motor strip –> UMN –> internal capsule —> midbrain –> pons –> rostral medulla –> LMN—> spinal cord
UMNs in the corticobulbar tract end in the ______
brainstem
What are the four indirect pathways of the motor cortex?
rubrospinal, reticulospinal, vestibulospinal, and tectospinal
What are general symptoms of lesions to the indirect pathway?
postural imbalance, increased stretch reflex, spasticity, hypertonus
What are general symptoms of lesions to the direct pathway?
loss of skilled movement, impaired deep tendon reflexes, Hypotonia, babinski sign
How is the corticobulbar tract affected when someone has a large right MCA stroke?
left side of head, face, and neck are weak, issues with CN VII and XII, dysarthria, swallowology issues, and visuospatial issues
How is the corticospinal tract affected when someone has a large right MCA stroke?
hemiplegia on the left side (left side of the limbs and trunk are paralyzed)
How is the corticobulbar tract affected when someone has a small left hemisphere stroke that affects left MCA anterior ventral distribution?
apraxia, nonfluent aphasia, another motor speech disorder, and some weakness to CN VII and XII
How is the corticospinal tract affected when someone has a small left hemisphere stroke that affects left MCA anterior ventral distribution?
weakness on the right side of the body (limbs and trunk)
Indirect pathways affects which neurons?
gamma LMNs
Direct pathways affect which neurons?
alpha LMNs
LMNs are not affected by these brain regions involved in movement
cerebellum and basal ganglia
Damage to what tract of the indirect pathway of the motor cortex causes spasticity?
left lateral medullary reticulospinal tract
Which two tracts of the indirect pathways do not receive information from the motor cortex?
tectospinal and vestibulospinal
Where does the tectospinal tract get information from?
visual and auditory systems
Where does the vestibulospinal tract get information from?
vestibular nuclei
Where does the rubrospinal tract start?
in the red nucleus of the midbrain
Rubrospinal tract gets information from the
cerebellum (part of the motor circuitry
Where does the vestibulospinal tract start? What is it responsible for?
the vestibular nuclei in the brainstem; innervates head and neck
Which of the tracts of the indirect pathway are bilateral and excitatory?
reticulospinal tract- pontine
Which of the tracts of the indirect pathways are bilateral and inhibitory?
reticulospinal tract- medullary
What is the function of the reticulospinal tract-pontine?
voluntary movements
What is the function of the reticulospinal-tract medullary?
reflex arcs
Decorticate posture is a result of damage to ______
corticoreticular tract
Corticobulbar tract has _____ and _____ pathways
direct and indirect
Where do the corticobulbar tracts start?
the ventral portion of the SMA, PMA, and PMC
Corticobulbar tract is also known as the _______
corticonuclear tract
What does the primary motor cortex (B.A. 4) do?
innervates spinal and cranial nerves 5,7, 9-12
What does the dorsal pre-motor area (B.A. 6) do?
does not affect speech; however, it’s responsible for visuomotor coordination, sensorimotor integration
What does the ventral pre-motor area (B.A. 6) do?
speech planning and perception; mirror neurons for motor
