Analysis on the function of orbicularis oculi muscle during the eye opening and closing movements

Objective:To analyze the function of orbicularis oculi muscle during eye-closing and opening movements. Methods: The electromyograms of a dog's orbicularis oculi muscle were extracted through some implanted micro-electrodes. The functional actions of the muscle during eye opening and closing movements were analyzed via the electromyograms. Results:The electromyograms of orbicularis oculi muscle during the natural eye-opening movement were similar to that during the natural eye-closing movement. The electrical activity of the muscle increased during eye-blinking events and during the change from eye-opening into eye-closing state. There was no any electrical activity observed during the change from eye-closing into eye-opening state. Conclusion:The contractions of orbicularis oculi muscle are needed for the implementation of eye-blinking and eye-lip closing movements during the change from eye-opening to eye-closing state. The continuous contractions are not needed for maintaining the eye-closing state.