EMG Flashcards
What does the EMG look like with spontaneous activity?
fibrillation potentials
positive sharp waves
On the EMG reading, above the baseline is considered ______ (pos/neg).
negative
What accounts for spontaneous activity?
acutely denervated muscle fibers have Ach receptors over the whole muscle fiber membrane rather than just at the neuromuscular jxn. This means the fiber is supersensitive and discharges spontaneously.
The wave in spontaneous potentials represents depolarization of ______.
single muscle fibers
NOT whole MUs
At rest, normal muscle is SILENT. What is it called when the EMG picks up sound at rest?
spontaneous potential
AKA fibrillation AKA pwave
Why would insertional activity be prolonged with diseased muscle or enervated muscle?
excessive exchange of ions across muscle membrane with needle stimulation
How can you distinguish fibrillations from fasciculations/?
fasculations are larger and more complex than fibrillation potentials
How can fasciculations can be distinguished from MUs discharging due to poor relaxation?
fasciculations are NOT under voluntary control
What is a fasciculation?
waveform that represents contraction of a group of muscle fibers; arises from discharge of part or all of a single MU
How does a fasciculation appear?
isolated discharges that recur at irregular intervals
How do you distinguish MUAP and fibrillation potentials?
look similar but MUAP are much bigger
What may be absent in complete denervation or reduced in partial denervation?
Interference pattern and MUAP
Positive sharp waves at rest are indicative of
spontaneous conductance
“Dive Bomber” is characteristic of
myotonic discharge
High frequency discharges are characteristic of
myopathies
myotonic dystrophy
At rest, what do you see as nerve recovers and muscle begins to be reinnervated?
increased insertional activity until all muscle fibers are reinnervated
