Relationship between dimensions of muscles of mastication (masseter and lateral pterygoid) and skeletal dimensions: Study of 40 cases

Abstract

The masticatory muscles play an important part in determining the morphology of the facial skeleton. Skeletal typology and the characteristics of the masticatory muscles are closely linked. Several authors have studied muscle characteristics as related to facial typology. The aim of this work is to study the relationship between vertical and transverse skeletal dimensions and the dimensions (length, width and thickness) of two muscles of mastication, the masseter and the lateral pterygoid. Our study was based on CT-scan examinations of a sample composed of patients consulting the X-ray department of the Rabat-Salé Teaching Hospital, and for whom a CT-scan had been requested. Forty CT examinations of the skull, performed in the context of sinus explorations or pre-surgical work-ups in the radiology department of the Rabat-Salé Teaching Hospital, were selected for this study. The sample comprised 19 women and 21 men aged between 20 and 45, with a mean of 40.9 ± 12.8. A Siemens 32-row 64-slice spiral CT-scan device was used for spiral acquisition of data around the facial bones, with the mouth closed. The study was carried out in the parenchymal window for the muscle measurements, in the axial and coronal planes. Bone measurements were performed after 3D reconstruction in VRT mode. Our study showed that, for the masseter muscle, thickness is the dimension that correlates significantly with skeletal dimensions in the vertical, transverse and sagittal directions. For the lateral pterygoid muscle, length and width both present significant correlations with transverse skeletal dimensions. Analysis of these results shows that the dimensional characteristics of the masticatory muscles vary according to the vertical and transverse skeletal typology of the subjects concerned.