SCALENE STRUCTURE AND FUNCTION IN THE MOUSE, MUS MUSCULUS
Michael R. Licatino (Jennifer L. Dearolf), Biology Department, Hendrix College, Conway, Arkansas 72032
Though the function of mammalian scalene muscle is generally unclear, studies have shown it to be a primary inspiratory muscle in several species and an accessory muscle in others. The purpose of this study was to test the hypothesis that the scalene acts as an accessory inspiratory muscle in mice. We utilized anatomical and histochemical methods, as well as comparative research, to better understand the role of the scalene muscle in mouse ventilation. The mean fiber-type profile of the mouse scalene was found to be 85.7% fast-twitch. In addition, the mouse had a significantly higher (p=0.017) average staining density of SDH (194 +/-22.1) than did the harbor porpoise (Phocoena phocoena) (136 +/- 31.9), indicating a greater concentration of this oxidative enzyme. However, the metabolic stains indicated that all fibers in the mouse scalene, regardless of fiber-type, had similar levels of oxidative enzymes. This finding suggests that the fast-twitch fibers are oxidative-glycolytic (FOG). Therefore, the mouse scalene has the potential to be a primary inspiratory muscle, but further studies are needed to accurately determine the function of this muscle.
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