electromyography Flashcards
emg
technique to measure/analyze electrical activity of skeletal muscles (myoelectric signals); detects from multiple muscle fibers as they are activated by motor neurons
myoelectric signals
electrical activity produced by skeletal muscles
does EMG work effectively for smooth muscles and why or why not?
not consistently effective cuz smooth muscles controlled by autonomic nervous system & electrical activity weaker
Motor Unit Action Potential (MUAP)
action potentials in the motor units
what exactly does EMG measure (official sounding term)?
Motor Unit Action Potential (MUAP)
two types of EMG
Surface EMG (sEMG), Intramuscular EMG (Needle EMG)
Surface EMG
-electrodes placed on skin
-non-invasive
-biomechanics, rehab, sports science
-measures summation of electrical activity from multiple muscle fibers
Intramuscular EMG (Needle EMG)
-fine wire/needle electrodes inserted into muscle (invasive)
-detailed activity from individual motor units
-clinical diagnostics, neuromuscular disorders
raw sEMG can range between +/- ____ microvolts; typically frequency contents range between _ and ___ Hz
5000; 6 & 500
why need to rectify raw EMG signal
facilitates analysis and interpretation; ensures values contribute meaningfully to signal processing; stable representation of muscle activation
T/F: more ups and downs in EMG data means more high frequency components
true
why need to smooth EMG signal?
enhances usability and interpretability; removes high frequency noise; reveals trends in muscle activation; facilitates comparison across trials/subjects
after rectifying, to get smooth EMG data, apply __ to remove __
low-pass filter; high frequency noise
Delsys EMG system
small, portable system; small sensors placed along same direction as muscles
