Muscle Spindles

Question 1

What are muscle spindle endings are attached to?

Answer 1

Muscle fibers

Question 2

Muscle spindle innervation

Answer 2

Gamma motor neuron

Question 3

What is the sensory part of the muscle spindle attached to?

Answer 3

Nerve ending

Question 4

What are muscle spindles sensitive to?

Answer 4

Stretch

Question 5

What do muscle spindles consist of?

Answer 5

• 3-5 nuclear chain fibers
• 1-2 nuclear bag fibers

Question 6

Both the chain and bag fibers of the muscle spindles have small muscles at their ends called what?

Answer 6

Intrafusal muscles

Question 7

What are the muscle spindles’ bag fibers sensitive to??

Answer 7

Stretch velocity

Question 8

What are the muscle spindles’ chain fibers sensitive to?

Answer 8

Stretch length

Question 9

What information do the muscle spindles provide to the CNS?

Answer 9

• Muscle length
• Contraction velocity

Question 10

Where do muscle spindles lie relative to the muscle fibers?

Answer 10

Parallel

Question 11

Via this type of neuron, muscle spindle receptors sense a lengthening of the spindle and sends a signal to the spinal cord

Answer 11

Ia sensory afferent neuron

note afferent means sensory

Question 12

What does Ia input stimulate?

Answer 12

Alpha motor neuron

Question 13

What does the alpha motor neuron do?

Answer 13

• Contracts associated muscle
• Inhibits antagonistic muscle

Question 14

When an agonistic muscle contracts, the antagonistic muscle relaxes

Answer 14

Reciprocal inhibition