myograph

/ˈmaɪəˌɡræf/
noun
  1. An instrument that records the contractions of a muscle.
    • In the lab, we connected the myograph to the subject's forearm to track muscle activity during exercise.
    • The scientist used a myograph to measure how the frog's leg muscle twitched.
    • Modern myographs can display muscle movements on a computer screen in real time.