What are the most important functions of motor control?
Conducting voluntary actions. (Lots of reflex control feeds into smooth patterned movement such as that seen in response to a nearby explosion)
Adjusting body posture to provide stable background for movement. (Other systems feed into it like vestibules and vision)
Coordinate action of various muscles to make movements smooth and precise. (Motor learning can be stored and brought about. Stored in the cerebellum and basal ganglia)
What does the basal ganglia do to a thought about an action?
It refines it so that it translates into an appropriate action.
What does the cerebellum do to a thought about an action?
(i.e Evaluates a thought with what we are currently doing. )
What does the cerebellum do to a thought about an action?
(i.e Evaluates a thought with what we are currently doing.)
What is the role of the spinal cord in motor control?
Controls local movement patterns and reflexes.
What is the role of the brainstem in motor control?
Continuous modification of tone in different muscles
What is the role of the cortex in motor control?
Issues sequential commands and is important for complex patterns and practiced movements.
What is the role of the cerebellum in motor control?
Motor planning, coordination, and assessment. It modulates and coordinates postural movements and accessory motor function.
It also provides predictive patterns of movement
What is the role of the basal ganglia in motor control?
Helps cortex execute subconscious learned patterns of movement.
It also helps plan multiple parallel and sequential patterns of movement
What are the 3 phases of motor control?
Strategy (What to do)
Tactics (How to do it)
Execution (Doing it)
What controls strategy in the hierarchy of motor control?
Posterior parietal cortex
What controls tractics in the hierarchy of motor control?
Pre-motor cortex and supplementary motor area
What controls execution in the hierarchy of motor control?
Primary motor cortex
What happens in the primary motor cortex and where does the input occur?
Primary motor cortex is the point of no return where an action is initiated. It receives input from supp. motor area.
Patterns are assembled in supplementary motor area after receiving input from everywhere else.
What are the direct control pathways of movement?
Corticospinal tract (most important)
What does it mean to say direct control pathway?
Direct pathway from the cortex to the spinal cord
In the corticospinal tract where does the UMN terminate?
In the spinal cord at the level of decussation.
Where are the UMNs located in the rubrospinal tract?
2 UMNs in relay are present in the brain one starts at the motor cortex and the other starts at the red nucleus
What muscles do the nerves of the corticospinal tract innervate?
Lateral corticospinal tract innervates distal limb muscles which influence fine movement, coordination and skills.
Ventral corticospinal tract innervates proximal limb muscles and provides innervation for gross movement.
Why does lateral corticospinal tract contain 80% of nerve fibers?
It provides innervation for more complex movements compared to the 20% that innervates proximal limb muscles which don’t need to be as complex.
What does the rubrospinal tract do?
It’s an accessory route for transmission of signals.
It innervates distal limb muscles and provides innervation for fine movements and control.
Where does the tectospinal tract start and go to?
Starts at superior colliculi of brainstem and descends through spinal cord.
What does the tectospinal tract do?
Receives visual input and provides output to muscles of the head and neck.
What do Vestibular nuclei do?
Receive input from the vestibules of our ear detecting equilibrium. Fibers then descent through spinal cord, our cerebellum, and our pontine reticular nuclei resulting in adjustments to postural adjustments.
What are reticular nuclei hooked up to?
The reticular formation in our brain and monitoring activity in our brain and they excite antigravity muscles.
What kind of adjustments can be derived from the medial indirect tracts?
Reticulospinal tract adjusts rigidity of muscles
Vestibulospinal tract adjusts for gravity and equilibrium
Tectospinal tract adjusts for visual cues.
Where does the reticulospinal tract get its input from?
Where does output from the reticulospinal tract go?
The pontine RST is excitatory and excites axial and extensor function.
The medullary RST is inhibitory and inhibits extensor muscles and excites flexor muscles.
Which part of the brain adjusts movements to make them align with the intended movement?
What happens if there is a lesion to the cerebellum?
Coordination is lost without paralysis.
Dysynergia: Losing synergistic multijoint movements
Dysmetria: Overshooting or undershooting target
Where does the cerebellum get its input?
From brain via cortical motor control outputs, vestibule (balance and hearing), basal ganglia and spinal cord.
From periphery cerebellum gets information from dorsol spinocerebellar tract (spindles and GTOs), spinal cord anterior horns via ventral spinocerebellar tract
Which cerebellar nuclei are important for balance and eye movements?
Vestibular nuclei from vestibulocerebellum.
Which cerebellar nuclei are important for motor planning?
Dentate nucleus which projects information from lateral hemispheres (cerebrocerebellum) to the cerebrum.
Which cerebellar nuclei are important for motor execution?
Fastigial nucleus (medial descending systems)
Interposed nuclei (lateral descending systems)
What does the spinocerebellum do?
Adjusts ongoing movements (limb muscles)
What does the cerebrocerebellum do?
Pays attention to motor planning of sequential limb movements.
Which of the parts of the cerebellum can be largely replaced by the basal ganglia?