Electromyography of the human cheeks and lips

Abstract To clear up indecision and disparities in the literature of muscular functions in the cheek and lips, multichannel electromyography with fine‐wire intramuscular electrodes was used in eight subjects. Both facial expressions and musical performance were investigated. Intersubject variations were common in the various muscles and intrasubject variation also appeared. The production of specific notes at specific volume on the trumpet or trombone did not depend on exact patterns of activity in the muscles of the lips and buccinator. Gentle puffing out of the cheek produces little or no activity in any muscle, but when this is done forcefully the orbicularis oris activity is marked. Buccinator can be kept deliberately relaxed or active during puffing. Smiling always produces buccinator activity as does forceful retraction of the corners of the mouth. Levator anguli oris activity always recruits concurrent buccinator activity but the reverse is not true.