Neuromotor System

Question 1

List the components necessary for motor control and describe their basic functions

Answer 1

Volition – what kind of movement do you want to make?

Coordination of many muscles – the interface between neuroanatomy and gross
anatomy

Proprioception – where is your body?

Postural adjustment – don’t fall over when you shift your center of mass

Additional sensory feedback (e.g., visual) – compare desired activity with actual
activity

Compensation for body – must account for mass of own body elements, which resist
movement

Nonconscious processing – automation

Adaptability – learn how to play the guitar, throw a curve ball, or shape sounds into
words

Question 2

Explain how the motor system components are hierarchically organized

Answer 2

Cortical components (highest level of hierarchy):
-Motor cortex: Pyramidal upper motor neurons in the primary motor cortex
-Premotor cortex: Planning, executing, directing voluntary movements, control
pyramidal UMNs

Non-motor cortical areas:

• Visual cortex: Visual guidance of movements
• Parietal cortex: Integrates visual, proprioceptive, and mechanosensory signals

Side loops routed through the thalamus:
-Basal ganglia: Initiates movements, suppresses non-synergistic movements, ‘chunks’
elements into action sequences
-Cerebellum: Coordinates movements and corrects errors in performance

Brainstem components (middle of hierarchy):
-Brainstem UMNs: Extrapyramidal pathways adjust tone and posture
-Pedunculopontine Nucleus: Midbrain locomotor center activates spinal pattern
generators for locomotion

Functional Effector Groups (lowest level of hierarchy in brainstem and spinal cord):

• Local circuit neurons: Central pattern generators in the reticular core
• Motor neuron pools: Columns of lower motor neurons innervating whole muscles
• Skeletal muscles: move the body!
• Proprioceptive feedback: Sensory consequences of movement

Question 3

Describe the essential elements and properties of the motor unit and motor pool

Question 4

Define ‘rate code’ and ‘size principle’ and relate these concepts to muscle force production

Question 5

Explain how the gamma motor system works to maintain muscle spindle function and muscle tone, and explain what is meant by “alpha-gamma coactivation”

Question 6

Describe the anatomy, function, activation, and control of central pattern generators by propriospinal neurons and descending systems

Question 7

Describe the network involved in planning and preparing movements, and summarize how the premotor cortex can be utilized to retrain lost motor functions

Question 8

Describe in brief the systems for motor learning and ‘hitting the target’

Answer 8

basal ganglia system

cerebellar system

Question 9

What are the Upper Motor Neuron Signs?

Answer 9

o Hypertonia (e.g. spasticity)
o Hyperreflexia
o Positive Babinski sign
o Clonus
o Paresis/Plegia

Question 10

What are the Lower Motor Neuron Signs?

Answer 10

RIGIDITY

o Paralysis
o Atrophy
o Hypotonia
o Hyporeflexia