The masticatory muscles are characterized by specific functional, histochemical, and micro-morphological properties, which distinguish them essentially from other striated muscles of the trunk and the extremities. Especially, the endowment of the muscle fibers with a redundant variety of myosin-isoform combinations gives this musculature an almost unlimited repertoire of contraction behavior. Along with the so-called heterogeneous activation capability, which allows the generation of discrete force vectors within the individual muscle, these properties provide the basis for sophisticated fine motor control of the masticatory muscles. Furthermore, the differential internal structuring is evidence for scientific hypotheses, which might explain not only the biomechanics of muscle micro-lesions, but also the therapeutic effectiveness of oral splints. Keywords: masticatory muscles, differential activation, muscle pain, temporomandibular disorders, oral splints