NMS 7/16/98
Spindles
-can’t have trigger points without spindles
-trigger point=area of spasm within a muscle
-strain/sprain, fibromyalgia
-spindle’s only job is to make MU contract
-spindles tell alpha motor neuron to tighten things up
-provide resting tone (need tone for stability)
-synergism between muscles
Agonist facilitation
-ex. rhomboids related to shoulder girdle (share same nerve root)
-can feed back and affect each other
Most shoulder problems
-supraspinatus tendonitis bursitis
Get spillover in cord (CES)
-this is how it affects agonists, antagonists
Reciprocal inhibition=Sherrington reflex
Stresses inc. higher center effect on gamma (ex. divorce stress)
-gamma then affects spindle, which affects Ia which affects alpha motor neuron
which leads to tighter muscles
-this is why fibromyalgia has an emotional component
-if you show pt. you care, it can help in healing (due to emotional aspect)
Facets-type I and II-->stimulate gamma
-if you stimulate gamma, you get spasm
-if you can block conduction, you can stop it (why irritation explains it better than
compression)
Somatosomatic reflex
-if can reduce the irritation, can reduce the spasms
-if can explain gamma-spindle-Ia-alpha motor neuron relationships to MD’s it will
help
Why would abdominal exercises help back muscle spasms?
-reciprocal inhibition (inc. ab tone-->dec. erector spinae tone)
Extrafusal muscle and spindle on stretch
-spindle is stretch receptor
-when muscle lenghtens-->dec. tone (from spindle’s viewpoint)
If you have a tight extensor muscle, need to stimulate spindles in flexor muscles (will help
decrease tone in extensors)
-ex. students have internal rotator muscles with inc. tone due to posture
Hypertonicity
-have full ROM, but it feels “tight”
Spasm
-lose ROM, but can still do isometric exercises (to get antagonists to contract so can
get agonists to relax)
Another possibility
-extrafusal fibers contract and spindle is slack (dec. Ia)
-in response, tonic gamma fires and spindle readjusts (tighter fibers, even if
shorter)
-higher centers told extrapyramidals to do something
-higher centers got info via dorsal columns (DC-->cerebellum-->higher centers)
High heels-stretch anterior muscles
-dec. posterior muscles (takes stretch off spindle)-->DC-->cerebellum-->higher
centers-->gamma-->spindle-->Ia-->alpha motor neuron-->extrafusal fibers
Null position=basline firing
-can reset to shorter length
-maintains stability
-when take heels off again, get crapms because spindles had adjusted to the new
length and don’t like the change back
Intrafusal fibers inside spindle
Phasic
-responds to quick stretch
-stimulates nuclear bag
Ia tonic
-stimulates nuclear chain
-constantly firing
Gamma
-affects Ia tonic firing-->results in return to baseline firing
For every movement of body, muscles have to balance out (return to null position as quickly as
possible)
Quick stretch of a flexor affects Ia phasic
-initially facilitates itself (homonymous excitation)
-inhibits an extensor (reciprocal inhibition)
Some people use quick stretch to relax a muscle-How?
-GTO fired by contraction
-stretching muscle fires stretch receptors
-stretch receptors tell muscle to contract
-muscle contraction fires GTO’s
Some people have more fast twitch muscles, some have slow twitch muscles (postural)
Postural muscles work better with GTO mechanism (as far as relaxing) than do fast twitch
-why fast stretch doesn’t work well on quads
Can only work synergistically with _______
-so quick stretch-->inhibit synergists
Small spinal muscles are non voluntary
-can only work with these synergistically
To relax a muscle
1)contract/relax/stretch therapy-->emphasizes GTO
-ex. have pt. push head against your hand-->shortens fiber-->Ia firing
dec., GTO firing inc.
-returns to null position within a longer muscle
-PNF=Proprioceptive Neuromuscular Facilitation (spindles, GTO’s)
2)ICA=Isometric Contraction of Agonist
-ex. headaches due to tight neck muscles
-push forehead against hand-->relaxes back neck muscles
3)Spray and stretch
-controversial
-methyl fluoride (a vapocoolant, chills the skin)
-spray from origin to insertion 4-5times, then stretch the muscle
-inhibits the stretch reflex
-do not use on deep back muscles
-good on peripheral muscles (hamstrings, etc.)
-makes you lightheaded
-can use ice instead
-idea of background afferentation (to cover up spasm input)
4)adjust the spine
Passive stretching
-helps some people (but not all)
Active stretching
-contracting agonist
-works better due to reciprocal inhibition
Could max stretch work due to type III fibers?
-NO, don’t stimulate III by just moving joint (need traction for III)