This article’s purpose is to explain the anatomicophysiologic basis for observations and measurements made by the electromyographer. An electromyographer may be trained in the techniques of electromyography without understanding the anatomicophysiology, and valuable interpretive subtleties may be missed. This article is an attempt to provide that background (ie, the link among anatomy, physiology, and electrodiagnostic findings). It is hoped that with a fuller understanding of the anatomicophysiologic basis of clinical electromyography, subtle observations can be made which will allow a more sophisticated level of interpretation of electromyography results. Such interpretations should improve the electromyographer’s capacity to provide useful information to a referring physician and hence, improve the management of a patient.