Abstract
To quantitatively elucidate individual variation in human masseter muscle, the cross sectional area of this muscle was measured in situ with MRI apparatus. The results were analyzed against age, body build and laterality in habitual mastication by bivariate correlation analysis. Materials included 52 healthy volunteers (26 males, 26 females) . Right and left masseter areas and total cross sectional area of the face were measured in the same horizontal plane, and directly displayed on the console of the MRI apparatus. Results: The areas of masseter muscles were not correlated with age or body build, but were positively correlated with the total cross sectional area of the face in the same horizontal plane. Because the left masseters tended to be larger than right, a method for evaluation of the relative size of each side of the masseters was established. This analysis revealed that the corrected dominance of the masseter corresponded, with high probability, to the habitual laterality in mastication.
