Muscle Spindle & GTO Neurophysiology & Application - E1 Flashcards
Learn the basics of mm spindle and GTO fibers and neurons and apply it to reflex Arcs, DTR, Clonus, Tonic Reflexes
What do muscle spindles sense?
Change in muscle length
What do GTOs sense?
Change in muscle tension/force
MM spindles run __ to true mm fibers (extrafusile)
Parallel
GTO run ___ to true mm fibers (extrafusile)
In series
What are mm spindles and GTOs primary function?
Proprioception
Where is the GTO?
At the musculotendinous junction b/t the tendon and muscle
List the two types of mm spindle fibers
Nuclear bag
Nuclear chain
What is a nuclear bag?
Either static or dynamic, a type of mm spindle fiber with a large diameter, with clustered, central nuclei
What is a nuclear chain?
A type of mm spindle fiber with a small diameter and nuclei spread out
T or F : mm spindles can contract
True - note striations at the end of mm spindle fibers
What is the primary receptor type of …
Ia phasics
Ia tonics
a&b) annulospiral receptors
What do a/b/c arise from?
a) Ia phasics
b) Ia tonics
c) Ib afferents
a) Dynamic nuclear bag cnetral area
b) Nuclear chain area
c) In GTO
What does (a/b/c) sense?
a) Ia phasics
b) Ia tonics
c) Ib afferents
a) Rate of mm lengthening (velocity) and mm length changes
b) Just mm length changes
c) Tension/force changes (passive/active elongation)
Ia phasics [facilitate/inhibit] the agonist via ___
Ia phasics FACILITATE the agonist via the alpha motor neuron (monosynaptic reflex arc)
Ia tonics [facilitate/inhibit] the agonist via ___
Ia tonics Facilitate the agonist via the alpha motor neuron (monosynaptic reflex arc)
Ia phasics [facilitate/inhibit] the antagonist via ___
Ia phasics INHIBIT the antagonist through the interneuron (diasynaptic reflex arc)
Ia tonics [facilitate/inhibit] the antagonist via ___
Ia tonics INHIBIT the antagonist through the interneuron (diasynaptic reflex arc)
What do the ascending fibers of Ia tonics, Ia phasics, and II afferents form?
The P/DCML
What does the quick stretch reflex stimulate?
The Ia tonic and Ia phasics
Give an example of reciprocal inhibition in an individual with a C7 SCI
Elicit contraction of triceps to facilitate (+) the triceps and inhibit the antagonist - biceps
Ib afferents [facilitate/inhibit] the agonist via ___
Ib afferent inhibit the agonist via an IN to alpha motor neuron (diasynaptic)
Ib afferents [facilitate/inhibit] the antagonist via ___
Ib afferent facilitate the antagonist via the alpha motor neuron (monosynaptic)
What is the basic mechanism to stimulate the GTO
cross fiber massage
How many mm fibers is a GTO connected to?
15-20 mm fibers
T or F: GTOs only respond to concentric changes
FALSE - respond to isometric, concentric, or eccentric w/as little as 2-25 g of force
Which fibers are responsible for crude gait?
II afferents with the crossed flexion-extension reflex (flexion ipsilateral, extension CL)
What neuron types are best at sensing quick stretch?
Ia phasics
What is clonus
Repeated, sustained contractions due to a quick stretch reflex
II afferents arise from ….
Flower spray receptors on the polar ends of the nuclear chain fibers and the static nuclear bag fibers
Stretch of mm spindle causes II afferents to ….
Send sensory information to the spinal cord
What neuron fibers contribute to crossed extension reflex?
II afferents
II afferents [facilitate/inhibit] the …. via _____
a) IPSI flexor
b) IPSI extensor
c) CL flexor
d) CL extensor
a) Facilitate the ipsilateral flexors via the alpha motor neuron (monosynaptic)
b) Inhibit the ipsilateral extensors via an IN to the alpha motor neuron (diasynaptic)
c) Inhibit the contralateral flexors via an interneuron to the alpha motor neuron (diasynaptic)
d) Facilitate the contralateral extensors via the alpha motor neuron (monosynaptic)
What are the key mm still function for an individual with a C4 SCI
Upper Traps, Accessory neck mm, deep neck mm, diaphragm
What are the key mm still function for an individual with a C5 SCI
Biceps, wrist extensors (ASIA - elbow flexors)
What are the key mm still function for an individual with a C6 SCI
Wrist extensors, SA, Lats (ASIA - wrist extensors)
What are the key mm still function for an individual with a C7 SCI
Triceps, Intercostals mm of first seven ribs, back extensors C1-C7 (ASIA - elbow extensors)
What is the scoring system for DTR?
A continuum:
0 & 1: hypoactive
2: normal
3 & 4: hyperactive
0 = absent \+ = hypoactive \++ = normal \+++ = brisk \++++ = hyperactive
What is a hypertonic reflex indicative of?
An UMN lesion -
An uncontrolled or uninhibited reflex arc activity
What is a hypotonic reflex indicative of?
A LMN or UMN lesion -
An underfacilitated relfex arc activity
What do you measure with a modified ashworth scale (MAS)?
Hypertonicity only
What do you measure with DTRs?
Hypertonicity or hypotonicity
What is the scoring system of the modified ashworth scale (MAS)?
A continuum:
0 = normal
1, 1+, 2, 3, 4 = increasing levels of hypertonicity
When is passive stretching the MOST appropriate?
When there are NO FUNCTIONING mm around the joint - neither agonist, synergist, or antagonist
What is the most appropriate stretching mechanism with a mm contraction end-feel?
Active stretching technique to stretch mm better
What is the most appropriate stretching mechanism with a myofascial restriction end-feel?
Myofascial release techniques