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Electromyographic study of the activity of jaw depressor muscles before initiation of opening movements
Author(s) -
Uchida S.,
Inoue H.,
Maeda T.
Publication year - 1999
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1046/j.1365-2842.1999.00401.x
Subject(s) - electromyography , digastric muscle , medicine , anatomy , duration (music) , temporal muscle , masseter muscle , orthodontics , physical medicine and rehabilitation , art , literature
The authors attempted to clarify the primary factors affecting the timing of the initial electromyographic discharges in the jaw depressor muscles (EMG onset). The changes in EMG onset in the inferior head of the lateral pterygoid (Lpt) and the anterior belly of the digastric muscles (Dig) were measured by varying duration of the open–close movement or occlusal force during the open–close–clench cycle (OCC). EMG onset tended to precede the beginning of the opening movement during OCC. The duration of opening and closing phase and the duration of occluding phase showed no significant correlation with the time‐lag between EMG onset and the beginning of the opening movement (onset time).The mean EMG activity of the masseter muscle (Mm), corresponding to the occlusal force, showed a highly significant correlation with the onset time. The maximal opening velocity was highly correlated with the mean EMG activity of the jaw depressors before jaw opening. In conclusion, it was found that occlusal force is a major factor in EMG onset in the jaw depressors. It is suggested that smooth opening needs tooth contact with some degree of occlusal force.