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Motor System
Details of the motor system
Question | Answer |
---|---|
Name the parts of the basal ganglia. | The caudate nucleus, the lentiform nucleus (containing the putamen and the globus pallidus). |
What is the motor system responsible for? | Voluntary movement of skeletal muscles and background posture and muscle tone. |
What are the four neural substrates for movement? | Motivation, Ideation(activity to achieve goal), Programming(unconscious motor plan), and Execution. |
Name the four programming centers. | Premotor Cortex, Supplementary Motor Cortex, Basal Ganglia, and Cerebullum. |
What is the Supplementary Motor Cortex responsible for? | Sequencing movements, particularly memory-guided ones. |
Which area of the brain contains half of the neurons in the entire nervous system? | The Cerebellum. |
What is the cerebellum responsible for? | Ensures movement is carried out as planned, by comparing the intended with the actual movement and modifying the output of the descending motor system as needed. |
Damage to the cerebellum can result in what? | Ataxia, incoordination of movements, or dysmetria, lack of coordination concerning distance |
What is the main role of the basal ganglia? | The main role in normal movement is the inhibitory effect of the basal ganglia on the thalamocortical circuit. |
What is the corona radiata? | Fan like motor tracts that descend through the cortex. |
What is the internal capsule? | Continuation of motor tracts that leave the cortex and pass through the basal ganglia and thalamus. |
Where does the corticospianl tract originate? | Sensorimotor areas of the cerebral cortex. |
What is the destination of the corticospinal tract? | The gray matter of the spinal cord. |
What are the three functions of the corticospinal tract? | Voluntary movement, fine motor control and reflex regulation. |
What is the path of the corticospinal tract? | From the cortex, through the internal capsule, the cerebral peduncle at the midbrain level, and decussate at the medulla. |
Why is the corticospinal tract referred to as the pyramidal tract? | Because of the large number of axons that form a pyramid on the ventral surface of the medulla. |
Where do the corticobulbar neurons terminate? | In the reticular formation of the brainstem. |
Name the direct pathways of the motor system. | Corticospinal and corticobulbar. |
Name the indirect pathways of the motor system. | Vestiblospinal tract, rubrospinal tract, and reticulospinal tract. |
What differentiates upper motor neurons from lower motor neurons? | Upper motor neurons are encased in bone while lower motor neurons have axons that are outside of bone, although the cell body may originate in the CNS. |
What are some of the characteristics of lower motor neurons? | Lower motor neuron are multipolar cells, they have extensive dendritic arborization, and each one receives 1000's of synapses from higher centers and interneurons. |
What are four mechanism of a simple reflex arc? | 1 - receptor organ, 2- afferent neuron, 3- efferent neuron, and 4- effector organ. |
What key functions do reflexes play in motor control? | They adjust for unexpected changes, they assist with coordination of ongoing muscle activity, and the allow rapid protection from pain. |