An anatomic study of the attachments on the condylar process of the mandible: muscle bundles from the temporalis

Purpose

The aim of this study was to evaluate anatomically the relationship between bone and muscles by detailed observation of the bone shape and the structure of muscles to facilitate an understanding of the function of the muscles involved in jaw movement.

Methods

36 specimens of 24 Japanese cadavers were examined. The insertion areas were marked using a radiopaque marker and examined by micro-computed tomography. For morphological observation, we used 101 condylar processes. In addition, we made histological sections in some specimens to observe the detailed attachments of the muscle.

Results

Based on the micro-CT images and dissection findings, the lateral pterygoid muscle was found to be most frequently inserted into the anterior impression and attached to the medial impression of the process. According to the histological observations, the lateral pterygoid muscle mainly inserted to the condylar process. The micro-CT images indicated that the obvious bony ridge was lateral to the pterygoid fovea on the condylar process in all specimens. The midmedial muscle bundle of the temporalis was attached to the ridge. Based on the morphological observations, the ridge was situated on the lateral area of the condylar process.

Conclusions

Since dysfunction of the temporomandibular joint is likely closely related to both the lateral pterygoid muscle and also the temporalis, further studies are necessary to evaluate the function of these muscles and consider jaw movement.