ABSTRACT
Craniomandibular muscles have been characterized by their gross anatomy, their functional recruitment as determined by electromyography, and their function as defined biochemically by the presence and concentration of specific enzymes. Biochemical studies have provided a mechanism for sampling small regions of these muscles by biopsies, and then selectively staining the chemical tags related to specific enzymes within individual muscle fibers. Such a study is defined under the broad term of histochemistry and provides a histological tool for visualizing the individual muscle fiber, the type of enzyme, and its approximate concentration within the muscle fiber. Depending upon the enzymes tested, the speed of contraction and the metabolic properties of the muscle can be predicted for individual muscle fibers and extrapo lated to the function of the entire muscle by determining the proportion of muscle fiber types. Histochemistry has become a valuable tool in determining how the different craniomandibular muscles vary from each other, how the regions of the muscles differ, and how their functional characteristics change with postnatal development and use.
