fig4
![Pre-operative electrodiagnostic studies and intraoperative neurophysiologic monitoring: power and pitfalls](https://image.oaes.cc/768e5a9f-6a1a-463c-99ac-81016b118ac3/5403.fig.4.jpg)
Figure 4. Spontaneous EMG recording demonstrating trains of neurotonic activity from several motor units in the orbicularis oculi and multiple motor units in the orbicularis oris muscles during facial nerve retraction. Note the superimposed electrocardiogram artifact in the trapezius muscle recording. Amplitude is 20 µV per division. The sweep speed is 400 msec per division.