Patterns of coordinated lower facial muscle function and their importance in facial reanimation.

Coordinated patterns of lower facial muscle activity have been observed using 8-channel electromyography (surface electrodes in a bipolar configuration) on 11 healthy volunteers to provide a picture of the patterns of muscle activity during function. Measurements of integrated electrical activity were made to allow comparison of different muscle groups during active, active-against-resistance, and passive movements. A contraction reflex was assessed by an electromechanical device and noted in 8 of 11 subjects. Lower facial movements were found to involve simultaneous bilateral activity in all the muscle groups tested bilaterally and to require a balance between dilator and constrictor forces. The significance for facial reanimation surgery is that it is desirable to reconstruct balanced constrictor and dilator forces, the latter having vector pulls upwards, downwards and laterally to reconstruct the normal mechanism of lower facial movement.