Motor Control 1 Flashcards
Motor control is a functional hierarchy with how many levels
3
High
Middle
Low
What is present in the high level functional hierarchy and what is its function
Association neocortex
and basal ganglion
Purpose = strategy
(the goal the movement strategy to best achieve this goal)
What is present in the middle level functional hierarchy and what is its function
Motor cortex
Cerebellum
Purpose = tactics
(the sequence of spatiotemporal muscle contractions to achieve a goal smoothly and accurately)
What is present in the low level functional hierarchy and what is its function
Brain stem and spinal cord
Purpose = activation of motor neurone and interneurone pools to generate goal directed movements
What do lateral pathways control
Voluntary movement
What do ventromedial pathways control
Posture and locomotion
Ventromedial pathways are under what control
Brain stem (nuclei)
Lateral pathways are under what control
Direct cortical control
What are the two pathways in the spine
Lateral pathway
Ventromedial pathway
What are the two lateral pathways that control voluntary movement
Corticospinal tract
Rubrospinal tract
What are the four ventromedial pathways that control posture and locomotion
Medullary reiculospinal tract
Pontine reticulospinal tract
Vestibulospinal tract
Tectospinal tract
What is the function of the corticospinal tract
Carries fibres from cerebrum & brainstem to skeletal muscles via spinal cord
What is the overall route for the tract of the lateral and ventromedial pathways
Descending tracts travel in white matter (because they’re myelinated) then synapse with LMN cell bodies in ventral ramus grey matter of the spinal cord
What is the longest tract in the body
The cortospinal tract
Where does the Cortospinal tract originate
2/3
Areas 4 and 6 (brodmann) frontal primary motor cortex
1/3 somatosensory cortex
Where does the corticospinal decussate (cross over)
At the medulla- spinal cord junction
What does decussation of the corticospinal tract result in
Right motor cortex controls left side : left motor cortex controls right side
Where does the corticospinal tract axons synapse
ventral horn motor neurones and interneurones to control muscles
Where does the rubrospinal tract start
In the red nucleus of the midbrain
What symptoms arise due to lessons in CST and RST
fine movements of arms and hands lost
(Can’t move shoulders, elbows, wrist and fingers independently)
What occurs if CST has a leison on it own
fine movements of arms and hands is again lost but function repairs after a few months as is taken over by RST
What is the function of the vestibulospinal tract
Maintain balance and posture when head moves so stabilizes the Head & Neck
What is the function of the Tectospinal tract
Ensures eyes remain stable as the body moves
Where does the vestibulospinal tract originate
Vestibular nuclei in the medulla
Where does the tectospinal tract originate
Superioir colliculus in the midbrain
Where does Pontine and medullary reticulospinal tracts originate
Brainstems reticular formation
What is the function of the
Pontine and medullary reticulospinal tracts
Use sensory information about balance, body position and vision to reflexly maintain balance and body position
What does the pontine and medullary reticulospinal tracts innervate
Trunk and antigravity muscles in limbs
What is the pathway of descending motor control
- Primary motor cortex/pre motor areas
- Upper motor neurones in the cortex/brainstem
- white matter of spinal cord as tract pathways
- Lower motor neurones in the grey matter of spinal cord
How are lower motor neurones distributed
Somatotopic
-specific relation between particular body regions and corresponding motor areas of the brain
Lower motor neurones are located where in the spinal cord
The grey matter
Where does the the Lower motor neurones more lateral in the grey matter innervate
Distal limb muscles
Where does the the Lower motor neurones more medial in the grey matter innervate
Proximal limb and axial muscles
How do white matter tracts differ from lower motor neurones
In origin and function
Where is the primary motor cortex (area 4) located
Precentral gyrus
Where is the premotor cortex (area 6) located in relevance to primary motor cortex
Anterioventral to the percentile gyrus
closer to the nasal/oral area
What areas of the cortex are involved in planing and instructing the voluntary movements
Primary motor cortex (Area 4)
Premotor areas/supllementary Area 6
Prefrontal cortex
Primary Somatosensory Cortex (Post-central gyrus)
Posterior Parietal Cortex (Visual Input) (Area 5&7)
What information does the cerebral cortex need to function
where the body is in space
where it wants to go
and select a plan to get there
What is the two areas that make up area 6
Premotor area
Supplementary motor area
How does supplementary motor area innervate motor units
Directly
How does Pre motor area innervate motor units
connects reticulospinal neurones innervating proximal motor units
How is the somatotopic motor map not precise
It does not represent upper motor neurones causing individual muscle movements
is functional rather than muscle specific
What does microsimulation in specific area of primary motor cortex elicit
coordinated movements of hand and mouth
or
movements that bring hands into central space to inspect/manipulate objects
What is the purpose of posterior parietal cortex (areas 5 and 7) in for the cerbral cortex coordination of body movement
To give a mental image of body in space is generated by somatosensory, proprioceptive and visual inputs
What is the function of the prefrontal and posterior parietal cortex combined
Decide what movement to make
What is the function of area 6 in coordinating body movements
Encodes signals from the axons of prefrontal and parietal cortex
and converts into how the actions will be carried out
firing the decision making neurones
What is the function of area 4 in coordinating body movements
Performs the movement by activating neurones of Corticospinal tract and Rubrospinal tract
When do premotor fibres fire action potential in relevance to when movement occurs
1 second before movement occurs
What makes the premotor area fire decision making neurones
When movement is made or rehearsed mentally
and when
watching others perform the movement
What is the two overall objective of motor circuits
to plan our movements and allow understanding of the actions/goals of others
What may premotor neurones also underpin
emotions and empathy
when may premotor neurones be dysfunctional
autism
