Lecture 3 - Motor Units Flashcards
What is a motor unit?
The alpha motor neuron and thousands of muscle fibres (+ the neuromuscular junctions)
What is a motor neuron pool
A group of alpha motor neurons that innervate a muscle
What is electromyography
A method to measure the electrical activity in muscles
How does differential EMG work
Measures the difference in electrical activity between two electrodes
How does needle EMG work
Measures action potentials of individual motor units
How does EMG signal measure motor unit recruitment
More signal = more contraction = more recruitment
What are the different MU recruitment thresholds
Low and high recruitment thresholds
What is hennemans size principle
smaller MUs with low thresholds will be activated before larger MUs and high threshold MUs
What are the types of MUs
S type
FR type
FF type
What are the characteristics of S type MUs
Slow
Small
Fatigue resistant
What are the characteristics of FR type MUs
Fast
Medium
Fatigue resistant
What are the characteristics of FF type MUs
Fast
Large
Fatiguable
What is the theory of central fatigue
muscles fatigue during exercise because of the reduced ability for alpha motor neurons to fire
