(S1W2) Control of Muscle Activation part 6

Question 1

What is a muscle spindle?

Answer 1

• stretch detector
• run along the muscle within the muscle
• detects changes in length and velocity of that muscle

Question 2

What is the purpose of a muscle spindle?

Answer 2

to detect if the muscle is stretching too much/too fast

Question 3

Example of what a muscle spindle does

Answer 3

• your hamstrings being stretched too fast during the swing phase of sprinting
• your muscle spindles within hamstring muscle will detect the change in length or increase in velocity
• then either stimulate that muscle to contract so it shortens or switch the opposite muscle (quadriceps) off

Question 4

What are the two missing labels? And what do these things do?

Answer 4

• top - bag fibre - detects changes in velocity
• bottom - chain fibre - detects changes in length

Question 5

What is a Ia afferent?

Answer 5

• a neuron in muscle spindles that takes sensory information from the muscle spindle to the central nervous system

Question 6

What is the difference between alpha ⍺ motoneurons and gamma γ motoneurons?

Answer 6

• ⍺ neurons stimulate skeletal muscles to contract
• a γ neuron do the same thing but for a muscle spindle

Question 7

What is the purpose of gamma γ motoneurons?

Answer 7

• can change length of muscle spindle to change its’ sensitivity
• and if the muscle shortens, rather than muscle spindle getting slack, can shorten the muscle spindle to maintain same level of sensitivity