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
1
Q
What do muscle spindles sense?
A
Change in muscle length
2
Q
What do GTOs sense?
A
Change in muscle tension/force
3
Q
MM spindles run __ to true mm fibers (extrafusile)
A
Parallel
4
Q
GTO run ___ to true mm fibers (extrafusile)
A
In series
5
Q
What are mm spindles and GTOs primary function?
A
Proprioception
6
Q
Where is the GTO?
A
At the musculotendinous junction b/t the tendon and muscle
7
Q
List the two types of mm spindle fibers
A
Nuclear bag
Nuclear chain
8
Q
What is a nuclear bag?
A
Either static or dynamic, a type of mm spindle fiber with a large diameter, with clustered, central nuclei
9
Q
What is a nuclear chain?
A
A type of mm spindle fiber with a small diameter and nuclei spread out
10
Q
T or F : mm spindles can contract
A
True - note striations at the end of mm spindle fibers
11
Q
What is the primary receptor type of …
Ia phasics
Ia tonics
A
a&b) annulospiral receptors
12
Q
What do a/b/c arise from?
a) Ia phasics
b) Ia tonics
c) Ib afferents
A
a) Dynamic nuclear bag cnetral area
b) Nuclear chain area
c) In GTO
13
Q
What does (a/b/c) sense?
a) Ia phasics
b) Ia tonics
c) Ib afferents
A
a) Rate of mm lengthening (velocity) and mm length changes
b) Just mm length changes
c) Tension/force changes (passive/active elongation)
14
Q
Ia phasics [facilitate/inhibit] the agonist via ___
A
Ia phasics FACILITATE the agonist via the alpha motor neuron (monosynaptic reflex arc)
15
Q
Ia tonics [facilitate/inhibit] the agonist via ___
A
Ia tonics Facilitate the agonist via the alpha motor neuron (monosynaptic reflex arc)
16
Q
Ia phasics [facilitate/inhibit] the antagonist via ___
A
Ia phasics INHIBIT the antagonist through the interneuron (diasynaptic reflex arc)
17
Q
Ia tonics [facilitate/inhibit] the antagonist via ___
A
Ia tonics INHIBIT the antagonist through the interneuron (diasynaptic reflex arc)
18
Q
What do the ascending fibers of Ia tonics, Ia phasics, and II afferents form?
A
The P/DCML
19
Q
What does the quick stretch reflex stimulate?
A
The Ia tonic and Ia phasics
20
Q
Give an example of reciprocal inhibition in an individual with a C7 SCI
A
Elicit contraction of triceps to facilitate (+) the triceps and inhibit the antagonist - biceps
21
Q
Ib afferents [facilitate/inhibit] the agonist via ___
A
Ib afferent inhibit the agonist via an IN to alpha motor neuron (diasynaptic)
22
Q
Ib afferents [facilitate/inhibit] the antagonist via ___
A
Ib afferent facilitate the antagonist via the alpha motor neuron (monosynaptic)
23
Q
What is the basic mechanism to stimulate the GTO
A
cross fiber massage
24
Q
How many mm fibers is a GTO connected to?
A
15-20 mm fibers
25
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
26
Which fibers are responsible for crude gait?
II afferents with the crossed flexion-extension reflex (flexion ipsilateral, extension CL)
27
What neuron types are best at sensing quick stretch?
Ia phasics
28
What is clonus
Repeated, sustained contractions due to a quick stretch reflex
29
II afferents arise from ....
Flower spray receptors on the polar ends of the nuclear chain fibers and the static nuclear bag fibers
30
Stretch of mm spindle causes II afferents to ....
Send sensory information to the spinal cord
31
What neuron fibers contribute to crossed extension reflex?
II afferents
32
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)
33
What are the key mm still function for an individual with a C4 SCI
Upper Traps, Accessory neck mm, deep neck mm, diaphragm
34
What are the key mm still function for an individual with a C5 SCI
Biceps, wrist extensors (ASIA - elbow flexors)
35
What are the key mm still function for an individual with a C6 SCI
Wrist extensors, SA, Lats (ASIA - wrist extensors)
36
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)
37
What is the scoring system for DTR?
A continuum:
0 & 1: hypoactive
2: normal
3 & 4: hyperactive
```
0 = absent
+ = hypoactive
++ = normal
+++ = brisk
++++ = hyperactive
```
38
What is a hypertonic reflex indicative of?
An UMN lesion -
| An uncontrolled or uninhibited reflex arc activity
39
What is a hypotonic reflex indicative of?
A LMN or UMN lesion -
| An underfacilitated relfex arc activity
40
What do you measure with a modified ashworth scale (MAS)?
Hypertonicity only
41
What do you measure with DTRs?
Hypertonicity or hypotonicity
42
What is the scoring system of the modified ashworth scale (MAS)?
A continuum:
0 = normal
1, 1+, 2, 3, 4 = increasing levels of hypertonicity
43
When is passive stretching the MOST appropriate?
When there are NO FUNCTIONING mm around the joint - neither agonist, synergist, or antagonist
44
What is the most appropriate stretching mechanism with a mm contraction end-feel?
Active stretching technique to stretch mm better
45
What is the most appropriate stretching mechanism with a myofascial restriction end-feel?
Myofascial release techniques
46
What is the most appropriate stretching mechanism with a soft end-feel?
Soft tissue mobilization (superficial to deep), scar mobilization, or functional massage
47
What is the most appropriate stretching mechanism with a joint/capsular end-feel?
Joint mobilization - not quite a "stretch"
48
Contract - Relax steps
1) go to point of restriction
2) pull against resistance (allow Pt to move a little)
3) As Pt relaxes, take the Pt out as far as they can --> new point of resistance
49
What is the neurophysiology behind contract - relax
Active concentric contraction of the agnoist may induce relaxation of the agonist (mm spindle neurophys)
50
Hold - Relax steps
1) Go to the point of restriction
2) Have Pt hooooooooold against resistance (NO MVMT)
3) As Pt relaxes, bring them into a new range
51
What is the neurophysiology behind hold- relax
Strong contraction of the agonist may trigger the GTO to inhibit the agonist (GTO neurophys) OR may cause immediate relax of the agonist after the strong contraction (mm spindle neurophys)
52
What are the steps of reciprocal inhibition
1) Go to the point of restriction
2) Have Pt hold against antagonist
3) Bring Pt into new range
53
What is the neurophysiology behind reciprocal inhibition
Facilitate the agnoist and Inhibit the antagonist via the mm spindle neurophys (Ia phasics come in and go to IN to inhibit the antagonist )
54
Cross fiber massage steps
1) Find mm tendon @ musculotendinous junction
2) Start at end of range
3) do cross fiber massage to stimulate GTO to get inhibition and more range
4) Move Pt into the new range
55
What is mm spindle bias?
The tendency for the mm to resume its original length since the mm spindle wants to assume its original, pre-stretch length
56
What is TVR?
Tonic vibratory reflex: vibrating the skeletal mm at a high frequency to induce a tonic contraction of the mm being vibrated
57
How does TVR work?
It selectively stimulates the mm spindle (Ia phasics) causing them to fire at the same frequency of the vibrator to facilitate the agonist and inhibit the antagonist
58
What Hz do you want to do TVR at?
60 Hz kids
100-120 for adults
over 200 can cause damage
59
Where should you be cautions with TVR?
Around the carotid arteries or other major blood vessels
| - do not want to dislodge a clot and cause a stroke
60
What is the neurophys behind cross fiber massage
Cause firing of the GTO to be >
Ib sensory nerve firing to inhibit agonist and facilitate the antagonist
61
What is the primary function of sensory receptors
To monitor the internal and external environment (detect force, proprioception, explore/manipulate the environment, detect harm)
62
Define sensation
Receptors receive and route info to SC to higher centers (for processing)
63
Define perception
The integration of sensory info from many sensory sources
64
What are III and IV afferents?
Cutaneous and joint receptors that bring proprioceptive info to the SC, cerebellum, and cortex BUT mostly just at extremes of range
65
What gives us the best information about joint position?
MM spindles and GTOs
66
How does the CNS regulate the sensitivity of our proprioceptive system?
Efferent motor neurons -
| when they are firing, they create enhanced sensitivity of the mm spindle
67
List some efferent neurons
Gamma motor neurons - static and dynamic
| Alpha motor neurons
68
What do ... innervate?
a) static gamma mn
b) dynamic gamma mn
c) alpha mn
a) static gamma mn innervate the contractile ends of the static nuclear bag and nuclear chain fibers (intrafusal)
b) dynamic gamma mn innervate the contractile ends of the dynamic nuclear bag fibers (intrafusal)
c) alpha mn innervate the extrafusal mm fibers
69
What regulates the efferent mn pathways?
Descending motor tracts
| eg: CST, VST, RST, etc
70
Give an example of enhanced proprioception
The firing of dynamic and static gamma mn at night to help increase proprioception to sense objects while walking at night
71
What composes a sensory unit?
Sensory receptors, a sensory neuron, and its many branches
72
List the sensory receptors - superficial to deep
```
Meissner's corpuscle
Merkle corpuscle
Free nerve endings
Krause
Corpuscle of ruffini
Pacinian corpuscle
```
73
T or F: Sensory receptors are transducers
True; they all convert one type of E to another (electro-chemical end result)
74
What is modality specific
when a receptor responds most efficiently to one type of sensory stimulus
75
What is a polymodal recptor?
responds to multiple stimuli - free nerve endings
76
What do meissner's corpuscles sense?
Pressure and touch (they are mechanoreceptors)
77
What do Krause receptors sense?
Cold
78
What do ruffini corpuscles sense
Warm
79
What to pacinian corpuscles sense
Touch and vibration in joints, tendon sheaths, and skin (mechanoreceptors)
80
What is a free nerve ending?
An unmyelinated terminal of myelinated and unmyelinated neurons
81
How are we able to sense the direction our hair is moved?
Free nerve endings that wrap around a hair follicle tell us direction of light touch
82
What do free nerve endings sense?
Cold, warm, touch, and pain
83
Define mechanoreceptor
Respond to physical stimulation that causes mechanical displacement of one or more tissues
84
Where do you typically find meissner's corpuscles
In the hairless portions of the skin (palms, soles, toes, fingers)
85
How does a pacinian corpuscle work?
It is a phasic receptor -
1) Pressure touch deforms it (depolorization) "on"
2) Fluid redistributes quickly in the corpuscle following deformation "off"
3) when stimulus is then removed, PC changes shape again (depolorazation) "on"
86
Phasic vs tonic receptor
Phasics are fast adapting (miliseconds) and tonic receptors are slow adapting (minutes, hours, days)
87
What are examples of phasic receptors?
```
Meissner's corpuscle (RA1)
Pacinian corpuscle (RA 2)
```
88
What are examples of tonic receptors?
```
MM spindle
GTO
Merkel cell (SA 1)
Ruffini ending (SA 2)
Carotid baroreceptor
```
89
What is on the pain ends of temperature feeling? (cold-pain and hot-pain)
Free nerve endings
| 0-15 and >45-50
90
What is the approximate T range for Krause receptors to be active (Celcius)
10-45 C w/peak between 20 & 30
91
What is the approximate T range for Ruffini receptors to be active (Celcius)
30-45 w/peak 40-45 C
92
What factors contribute to our perceievd temperature?
Air T
Wind speed
Solar and thermal radiation
Humidity
93
What are nociceptors
Detect pain -
| They detect actual or potentially destructive mechanical, chemical, or thermal changes in the immediate tissue
94
Hypertonicity is a result of a _MN lesion
UMN always
95
Hypotonicity is a result of a _MN lesion
UMN or LMN lesion
96
Two-point discrimination - from closest to farthest
a) forearm
b) back
c) Fingertip
Finger tip > forearm > back
97
What broadman areas is the pre-central gyrus
4
98
What broadman areas is the post-central gyrus
3, 1, 2
99
What is a receptive field
An area of the sense organ that when stimulated, will activate a single afferent neuron w/the center being the most sensitive to the stimulus
100
How does 2-pt discrimination work?
You will only perceive two different points if you overlap 2 different receptive fields. Receptive field size changes dependent upon where you are
101
Relationship b/t size of receptive field and sensory acuity
Inversely proportional - the smaller the receptive field the greater the sensory acuity
102
What is perception?
| Give an example
The integration of sensory information from many sensory sources (Vision, hearing, smelling, and touching)
- Recognizing your dog or cat as your own
103
What is graphesthesia
The ability to identify characters that are written on the skin - tests cortical sensation/perception
104
What are some ways to test cortical sensation/perception
Graphesthesia and sterognosis
105
What is sterognosis
The ability to identify objects placed in the hand with eyes closed
106
Asterognosis
The inability to distinguish two objects placed in the hand (tactile agnosia) or by sight (visual agnosia)
107
What is body image
Awareness of body parts and their relationship to one another and the environment
108
What are body image disorders?
Perceptual disorders associated w/PARIETAL*** and temporal lobe lesions (most commonly w/Right brain lesions)
109
What is asomatognosia
Lack of awareness of the body structure and the rln of body parts to one another
110
What is hemi-asomatognosia
Decreased awareness of one side of the body (usually on the Left)
111
What is hemi-spatial neglect
Most common on the RIGHT (non-dominant) PARIETAL cortex, causing patients to neglect the left side of their environment
112
What is apraxia
inability to follow a motor command that is not due to a primary motor deficit or language impairment, but a deficit in higher-order planning PLUS inability to carry out the motor plan
113
What is ideomotor apraxia
Can plan/conceptualize, but not carry out the motor tasks
| able to make gestures spontaneously, but cannot produce same movements if asked
114
What is ideational apraxia
Cannot come up with the plan or concept of the task & cannot carry out the action spontaneously or on command
