Movement Flashcards
What are the 3 tiers in the hierarchy of motor control?
1.) Strategy
2.) Tactics
3.) Execution
What is Strategy?
What is the goal of the movement and how to achieve the goal?
What parts of the brain are associated with the strategy of movement?
Association areas of the visual, somatosensory, and auditory cortices
What are Tactics?
The sequence of muscle contractions needed to achieve the strategy
What parts of the brain are associated with the tactics of movement?
Motor cortex, basal ganglia, and cerebellum
What is Execution?
Activation of specific lower motor neurons to contract appropriate muscles
What parts of the brain are associated with the execution of movements?
Brainstem and spinal cord
What are upper motor neurons?
From motor cortex or brainstem
What are lower motor neurons?
Motor neurons on spinal cord or connecting brainstem/SC to muscle effectors
Where is the primary motor cortex located?
In the precentral gyrus
Which of Brodmann’s areas houses the primary motor cortex?
Brodmann’s area 4
What is the primary motor cortex responsible for?
Volitional control of motor systems; precise movements
What happens when there is damage to upper motor neurons in the PMC?
Loss of movement on the contralateral sign; precise movements are lost first and hardest to regain
What is contained in the prefrontal cortex?
Large numbers of afferent and efferent pathways
What does the prefrontal cortex connect to?
1.) Other cortex areas
2.) Thalamus
3.) Hypothalamus
4.) Basal Ganglia
What 3 things are the prefrontal cortex responsible for?
1.) Defines individual’s personality and cognition
2.) Area where much of the highest-order processing is believed to take place
3.) Inputs to motor cortex with decisions about what actions need to be taken
Which of Brodmann’s areas houses the premotor cortex?
Brodmann’s area 6
Where does the premotor cortex receive input from?
Prefrontal cortex
What is the premotor cortex a major source of?
Corticospinal and corticobulbar tract neurons
Which of Brodmann’s areas houses the Posterior parietal cortex?
Brodmann’s areas 5 and 7
Where does Brodmann’s area 5 receive input from?
Primary somatosensory cortex
Where does Brodmann’s area 7 receive input from?
Visual cortex
What does the posterior parietal cortex do?
Connects to prefrontal cortex to assist with decisions about actions needing to be taken
What are 5 structures of the basal ganglia?
1.) Caudate nucleus
2.) Putamen
3.) Globus Pallidus
4.) Subthalamic nuclei
5.) Substantia nigra
What is the basal ganglia involved in?
Heavily involved in motor planning
What causes Parkinson’s Disease?
Degeneration of the substantia nigra
What is Parkinson’s disease characterized by?
Loss of dopamine release to the corpus striatum
What are symptoms of Parkinson’s disease?
Muscle tremors, rigidity, initiating movements, postural distrubances
What is paresis?
Muscle weakness and minor paralysis
What are tremors?
Uncontrollable movements
Why does paresis and tremors occur together in Parkinson’s?
Dopamine can be excitatory or inhibitory
What does loss of excitatory action on D1 cause?
Paresis
What does loss of inhibitory action on D2 cause?
Tremors
What is rigidity?
1.) A product of lack of excitation and inhibition
2.) Product of inability to contract to the main muscle
3.) Inability to inhibit the antagonist muscles
What kind of disorder is Huntington’s disease?
Autosomal dominant hereditary disorder
What does Huntington’s Disease affect?
The caudate and lentiform nuclei and parts of the parietal lobe of the cortex
When does Huntington’s Disease set on?
Around 30-40 years old
What does Huntington’s Disease do?
Creates cognitive deficits, dysarthric speech, and chorea movements
What is chorea?
Slow involuntary movements of the face and distal limbs
What does the descending motor pathways to the spinal cord do?
Connect the upper motor neurons to the lower
What are the 2 components of the descending motor pathways to the spinal cord?
1.) Lateral pathways
2.) Ventromedial pathways
What are lateral pathways?
Voluntary movement of the distal muscles
Where do lateral pathways originate?
In the cortex
What are ventromedial pathways?
Heavily involved in postural control and reflexive movements
Where do ventromedial pathways originate?
In the brainstem
How much of the total descending efferent motor fibers are contained in the corticospinal tract?
Only 30%
What is contained in the pathway of the corticospinal tract?
1.) Internal capsule between thalamus and midbrain
2.) Cerebellar peduncles
3.) Decussation of the pyramid
What is contained in the corticobulbar tract?
Efferent pathway from motor cortex to cranial nerves
Where does the corticobulbar tract emerge from?
The lower 1/3 of the motor cortex
