Contributions of individual muscles to the submental surface electromyogram during swallowing

Submental surface electromyographic recordings are commonly used in the inv estigation of swallowing disorders. The measured electromyography is though t to reflect the actions of floor-of-mouth muscles. Although this is a reas onable assumption, to date there have been no investigations to delineate w hich muscles contribute to this surface recording. The primary goal of this experiment was to determine which muscles contribute most to the submental surface. Electromyography was recorded simultaneously from the submental s urface as well as from five individual muscles: mylohyoid, anterior belly o f the digastric, geniohyoid, genioglossus and platysma. Three analysis meth ods were performed to estimate individual muscle contributions: correlation , numeric, and analytic. For the numeric and analytic analyses, a linear mo del was defined and used to represent the relationship between the surface and intramuscular recordings. Muscles that received a high correlation, num eric and/or analytic value were considered to be primary contributors to th e submental recording. Regardless of analysis approach, the primary contrib utions to the submental surface recording were the mylohyoid, anterior bell y of the digastric, and the geniohyoid muscles. Contributions from the geni oglossus and the platysma muscles were minimal. Contributions as a function of bolus volume and viscosity are also discussed.