Comparison of the craniofacial muscles: A unifying hypothesis

In the field of skeletal muscle research, most research has been performed using limb skeletal muscle, whether studying myogenesis or the anatomy, cell biology, biochemistry, and physiology of normal, diseased, or aging muscle. Early studies of limb muscle led to the description of four basic fiber types with specific biochemistry and physiological properties assigned to each. Evidence in the past decade has revealed that this is an oversimplified view of the true heterogeneity amongst the myofibers within limb muscles (Caiozzo et al. 2000, 2003; Pette and Staron 2000; Stephenson 2001).