It was confirmed that the electrical activity in the upper half of the masseter muscle differed from that in the lower half, since tendon tissue laid along the upper half of the masseter muscle.
This study was conducted for measuring the deep temperatures at the superior and inferior portions of the masseter muscle at rest. Twenty normal subjects (10 males and 10 females) and 10 patients with craniomandibular disorders were selected in this study.
The findings obtained were as follows:
1. In normal subjects, no differences were shown in the deep temperature between the right and left masseter muscles. The deep temperature was significantly higher in the superior portion of the muscle than in the inferior.
2. In patients, the difference of deep temperature between the right and left sides was shown both in the superior and/or inferior portion of the masseter muscle.