QUANTITATIVE-ANALYSIS OF MASTICATORY MUSCLES USING COMPUTED-TOMOGRAPHY

Quantitative information on the normal size range of the masticatory m uscles needed for successful treatment of facial asymmetry is sparse. Our purpose in this study was to define morphological indicators for t he volume of the masticatory muscles on CT. Cross-sectional areas and volumes of the masseter and medial pterygoid muscles were measured fro m CT scans of 65 patients. The muscles were scanned from origin to ins ertion and the maximum cross-sectional area (MCSA) and its location to gether with the total volume were determined. The mandibular foramen w as used as a landmark to determine the location of MCSA. The location of MCSA of masseter muscle was centred 8 mm above the mandibular foram en, and that of medial pterygoid muscle at the foramen. The MCSA of bo th muscles was highly correlated with volume suggesting that this para meter might serve as an indicator of their volume. Knowledge of the lo cation of the MCSA would facilitate its measurement, and so reduce rad iation exposure. There was a positive correlation between the two musc les for both volume and MCSA. This finding could be relevant for futur e studies of the relationship between the morphology, biomechanics and pathology of the masticatory muscles.