The medial pterygoid muscle: a stabiliser of horizontal jaw movement
Bibliographic record
Abstract
There is limited information of the normal function of the human medial pterygoid muscle (MPt). The aims were to determine whether (i) the MPt is active throughout horizontal jaw movements with the teeth apart and (ii) whether single motor units (SMUs) are active during horizontal and opening-closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed five teeth-apart tasks: (i) postural position, (ii) ipsilateral (i.e. right) jaw movement, (iii) contralateral movement, (iv) protrusive movement and (v) opening-closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least one horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilisation of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this muscle in oro-facial pain conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".