090314 muscle Flashcards
agonist
primary mover
often considered as functional muscle group
antagonist
oppose or reverse the action of the primer mover
synergists
assist the primer mover in actions
reciprocal inhibition
taken on by the antagonist muscle to enable smooth movement and the ability to stop the movement
how does reciprocal inhibition provide for maximal muscle efficiency, speed, and control?
antagonist muscle prepares to slow down or stop the intended fxn
muscle pair needs to coordinate their contractions to avoid injury
in neurologically intact pts, what type of reciprocal inhibition contributes to antagonist suppression in mvmt?
group Ia mediated
what is electromyography used to see?
the muscle’s activity during a certain action
assess integrity of muscle and the peripheral nerves supplying it
assess neuromuscular jxn
nerve conduction studies are a component of electromyography (assess integrity of peripheral nervous sys)
innervation ratio
number of muscle fibers innervated by a single axon or motor neuron
MUAP
motor unit action potential–created by depolarization of all the fibers in a motor unit
size principle of muscle recruitment
first, small motor units are recruited and then larger ones and then even larger ones over time
what do nerve conduction studies test?
motor, sensory, mixed nerves
what does electromyography test?
skeletal muscle fibers, mostly type I
concentric contraction
muscle shortens
eccentric contraction
muscle lengthens while contracting (controlled but gradual relaxation that generates a diminishing force or tension)
isometric contraction
muscle creating tension w/o movement or change in length
isotonic contraction
muscle changes length as it generates force
what does motion analysis and surface electromyography assess?
what muscles are contracting
see if contractions are concentric or eccentric
what times the muscle is contracting
compare normal to someone w/ stroke, or peripheral nerve injury
what do you see w/ upper motor neuron syndrome?
hyperreflexia, spasticity
weakness
no inherent muscle atrophy (lower motor neuron intact)
spasticity
velocity-dependent increase in tonic stretch reflex
hyperexcitability of the stretch reflex
one component of the upper motor neuron syndrome
botulinum neurotoxin is used for
intra muscular injections to reduce focal muscle overactivity
affects both intrafusal (sensory) and extrafusal(motor) muscle
may affect nociceptor pathways
can be used for blocking salivary and sweat glands
for numerous disorders: dystonia, spasticity, ophthalmologic, GI and GU, dermatologic, pain
botulinum toxin MOA
interferes w/ presynaptic Ach release
heavy chain targets presynaptic membrane, light chain gets endocytosed and cleaves the SNAP25 so docking is deficient
compound action potential for the median nerve
depolarizes every muscle innervated distal to the point of placement by the median nerve
