 In sleep apnea patients, the relatively early stimulation of the upper respiratory tract muscles compared to the thoracic respiratory muscles is abrogated in many cases. Alternatively, nerve damage with impaired sensory function in the pharynx area and impaired motor function of the upper air tract musculature, in particular the musculus genioglossus can be observed. The disturbed sensory function impairs the reflex activation of the genioglossus. Moreover, the pattern of neurogenic muscle damage with a loss of the pattern of different types of fibers changed to the point of adjoining atrophic and hypertrophic sections and a more monotonous appearance of fiber types could be detected. During waking hours the activity of the musculus genioglossus is enhanced compared with control persons, which is interpreted as a compensatory mechanism. During sleep time, however, this compensation seems to disappear. 