Association between craniofacial morphology and fiber-type distributions in human masseter and medial pterygoid...

Numerous experimental studies and clinical anecdotal evidence demonstrate a close interaction between masticatory muscle function and skeletal form. The purpose of this study was to determine whether a relationship existed between histochemical characteristics of human masseter and medial pterygoid muscles and cephalometric measurements of the 11 subjects from whom specimens were collected. Muscular specimens were obtained at the time of corrective surgery through incisions made to expose the mandibular ramus. Histochemical analysis was used to determine the size and distribution of fiber types. Angular and linear measurements were obtained from lateral cephalometric radiographs taken 1 week prior to surgery. Linear regression analysis revealed one significant negative correlation between ramus length and the percentage of Type I fibers in the medial pterygoid muscle. However, the results of this study do not support the hypothesis that a relationship exists between facial type and selected histochemical characteristics.