MORPHOLOGICAL MEASUREMENTS OF LATERAL PTERYGOID MUSCLE USING X-RAY CT IMAGES

Abstract

Although the lateral pterygoid muscle has been considered to be important in the analysis of jaw movement and temporomandibular joint disorders, its morphology still remains unknown.
The purpose of this study was to determine the normative morphological measurements of this muscle using X-ray CT images.
X-ray CT images of transverse views of the lateral pterygoid muscle were obtained from 54 patients who had no clinical findings for TMJ or abnormality of the masticatory muscles.
Volume, length, transverse and longitudinal cross-sectional areas of the lateral pterygoid muscle were measured using CT imaging.
The results were as follows:
1) In many cases the upper and lower caput of lateral pterygoid muscle could not be separately observed on reconstructed X-ray CT images.
2) Mean volume, transverse and longitudinal cross-sectionl areas, length were 7.18cm³, 3.49cm², 5.34cm², 3.58cm, respectively.
3) There was a significant correlation between measurement values for the right and left sides and a significant difference between genders in measurement values, but no correlation with age was found for any measurement.
4) Cross-sectional area of the muscle was significantly related to its volume.
By thus establishing the normal ranges of the various measurement values described above, We can represent quantiatively the rriorphological abnormalities of the lateral pterygoid muscle caused by TMJ disorders and facial deformities. In addition, the functional status of the lateral pterygoid muscle may be more precisely evaluated.