Muscle Spindle Cells

Question 1

Which muscles have a higher concentration of MSC, muscles with coarse movements or those with fine movements?

Answer 1

Fine movements

Question 2

Do small muscles close to the spine have a high or low concentration of MSC?

Answer 2

High

Question 3

Describe a Ia afferent fiber.

Answer 3

Sensitive to vibration, tap, stretch of muscle
Give info on velocity and position
Large and myelinated
Fast conducting/adapting, adjust quickly to muscle stretch

Question 4

In addition to stretch MSC are sensitive to ______________ and ____________

Answer 4

Vibration and taps of the muscle

Question 5

What is the difference between a tap or the patellar reflex and our HVLA?

Answer 5

Reflex hamper/Tap stimulates MSC Ia afferents on a relaxed muscle

HVLA stimulates GTO because joint is brought to tension

Question 6

How does high gamma gain protect our muscles from injury? What are the effects of low gamma gain?

Answer 6

Low gamma gain – muscle stretches too long before reflex contraction. This can lead joints outside normal ROM before the muscle reacts to protect them and lead to injury

Question 7

How can we increase gamma gain?

Answer 7

Training – leads to increase frequency of neuronal firing the muscle

Question 8

How does a long slow stretch affect the MSC?

Answer 8

Allows Ia affarents to accommodate and reset at a new level of stretch

Question 9

What effect does movement have on pain?

Answer 9

Decreases pain

Question 10

What are the effects of Ia afferent stimulation (7)?

Answer 10

1. Stimulates alpha motor neuron to agonistic muscles
2. Stimulates gamma motor neuron to the agonistic muscle
3. Stimulates the synergistic muscle
4. Ascends to the brain via three different pathways
5. Stimulates the IML (all sensory neurons stimulate the IML)
6. Inhibits nociception (pain)