1988 Fiscal Year Final Research Report Summary
A role of muscle spindle afferents in the control of masticatory jaw movements.
| Project/Area Number |
62480376
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Functional basic dentistry
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| Research Institution | Osaka University |
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Principal Investigator |
MORIMOTO Toshifumi Osaka Univ., Faculty of Dentistry, Professor, 歯学部, 教授 (20028731)
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| Co-Investigator(Kenkyū-buntansha) |
MASUDA Yuji Osaka Univ., Faculty of Dentistry, Instructor, 歯学部, 助手 (20190366)
INOUE Tomio Osaka Univ., Faculty of Dentistry, Instructor, 歯学部, 助手 (70184760)
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| Project Period (FY) |
1987 – 1988
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| Keywords | Jaw movements / Masticatory force / Muscle spindle / Mesencephalic trigeminal nucleus / ウサギ / 一次終末 |
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| Research Abstract |
Contribution of muscle spindle endings to the control of masticatory jaw-movements and jaw-closing muscle activities was studies 1) by examining the effects of making a lesion of the trigeminal mesencephalic nucleus (Mes V), in which ganglion cells of muscle spindle afferents locate, on EMG activities of the masseter muscle, and 2) by analysing activities of the Mes V neurons during chewing a test strip. The results are as follows : 1) the masseteric EMG activities during chewing a test strip were significantly reduced by lesioning the Mes V; 2) the Mes V units, which were excited at the beginning of both the jaw-opening and occlusion pheses, increased their firing frequency during chewing a test strip. They were sensitive to suxamethonium administration and supposed to be the primary spindle afferents. Based on these results, we conclude that the muscle spindles of jaw-closing muscles (presumably primary endings) contribute to the enhancement of jaw-closing muscle activities and thus increased the medial excursing of the jaw during the occlusion phase of a masticatory cycle.
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