Class 9

Question 1

What are Gamma Motor Neurons?

Answer 1

Motor neurons that innervate intrafusal fibres.

Question 2

What do intrafusal fibres do?

Answer 2

Adjust sensitivity of muscle spindle

Question 3

If there is more input from gamma motor neurons, fibres _____________, bringing _____ fibres closer together & making muscle spindle much more sensitive to stretch, & more likely to set off muscle contraction via _________________.

Answer 3

• contract
• 1a
• stretch reflex

Question 4

For patients with excess “gamma bias”, the la sensory endings within muscle spindles are…..

Answer 4

Discharging too frequently causing there to be more muscle activity than appropriate. This hyperactivity can cause hyperreflexia.

Examples of this can include twitching or spastic tendencies. These are indicative of lessening or loss of control that is ordinarily exerted by higher brain centers on gamma motor neurons.

Question 5

What is Hyperreflexia?

Answer 5

Hyperreflexia is defined as overresponsive reflexes

Question 6

What Is The Golgi Tendon Organ?

Answer 6

Proprioceptive receptor, located within tendons found on each end of muscle. Limits excessive contraction exerted on tendon by inhibiting further muscle contraction.

Unipolar neuron (Ib) carries signals from GTO to CNS via what is called inverse stretch reflex arc. This causes autogenic reflex inhibition (relaxation).

Question 7

What is PNF (Proprioceptive Neuromuscular Facilitation) Stretching?

Answer 7

Traditional explanation of underlying mechanisms of PNF stretching is reflexive relaxation occurs during stretching maneuvers, as the result of autogenic or reciprocal inhibition.

Current thinking suggests that increased ROM is the result of:
- viscoelastic adaptation of muscle-tendon unit
- changes in patient’s tolerance to stretching maneuver.
- more complex mechanisms of sensorimotor processing

Numerous studies have demonstrated that various PNF stretching techniques increase flexibility & ROM. There is no consensus on whether one PNF technique is significantly superior to another.

Question 8

When you stub your toe, you will feel touch sensation of your toe hitting ground first because information related to your toe touching ground is carried by _________________________________. A little bit later you will feel sharp nociceptive input by _____________________________ & then even slower dull throb of _________________.

Answer 8

• large, fast conducting A Beta nerve fibers
• slower conducting A-Delta
• C fibres

Question 9

What is the Pain Gait Control Theory?

Answer 9

In 1965, it referred to synapse in dorsal horn of SC between unipolar nociceptors & neurons of spinothalamic tract.

Closed “gate” described nociceptive transmission that was being blocked. Transmission could be modified by interneurons via two approaches.

1) non-painful sensations via faster large diameter axons (touch & proprioception) can override & reduce nociceptive sensations via slower small nerve fibres (A-delta and C fibres) in dorsal horn of spinal cord.

Eg. if you hit your finger with hammer, you might instinctively begin to rub it, shake it, or run it under cold water all of which may interfere with these pain/nociception sensations.

2) Afferent nociceptive signals to certain brain areas, can activate descending pathways. These descending signals inhibit ascending signals from nociceptors in dorsal horn & other regions by activating opioid & cannabinoid receptors in CNS

Massage, Exercise, & Meditation & Laughter are all capable of
stimulating these nociceptive blocking pathways.