Morphological study of lateral pterygoid muscle using axial X-ray CT

The normal morphology of the lateral pterygoid muscle (LPM) and changes in its length and width with aging were investigated by axial X-ray CT. The materials were taken from 145 patients with no evidence of occlusion and temporomandibular disorders. The following findings were shown with aging: (1) the length of lateral side of LPM tended to increase; (2) the length of medial side of LPM tended to decrease; (3) the width of the condylar area tended to increase; (4) there was no change in the attachment width of LPM at the pterygoid process of the sphenoid bone or at the condylar area; (5) the width of LMP at the level of the largest cross-sectioned area of the muscle tended to decrease; (6) the angle between condylar axis and LPM tended to decrease, and this was significantly noticeable in females than males. Three principal components were found to be (1) general size, except for the medial distance of LPM and the angle of LPM to the axis of the condylar area, (2) medial distance of LPM, and (3) width of LPM at the pterygoid process. (N.K.)