Amount Of Jaw Opening Research Articles

Segmental and Syllabic Articulations: A Descriptive Approach.

This article reports on jaw articulation, in connection with the segmental articulations of tongue tip and lips. The jaw is considered a syllable articulator as it opens and closes for each syllable, and the amount of jaw opening is related to syllable strength, given the same phonemic vowel. Here, we investigate the syllabic and the segmental articulations relationships to the acoustic segments. We analyze electromagnetic articulography data of 18 Southern Swedish speakers by testing hypotheses based on the Descriptive Approach to Segmental Articulations. In this approach, articulatory movements are divided into fast intervals and steady states, and the crucial ("primary") articulators' deceleration and acceleration peaks align with the acoustic segment boundaries. Previous findings on the lips and the tongue tip are confirmed. New results are the jaw as noncrucial ("nonprimary") does not align with the acoustic segment boundaries: Its steady states are shorter than consonant and vowel segments. Moreover, place of articulation of the coda affects the jaw cycle, while syllable type only affects jaw closing. No such effects are found on the edges of the jaw cycle, instead only gender affects jaw deceleration at syllable onset. The jaw is not crucial for the timing of the acoustic segment boundaries; also, syllable borders seem to not be affected by place of segmental articulation. The results strengthen the view of the jaw as syllable articulator providing a frame and the other articulators (e.g., lips and tongue tip) as the segmental articulators providing the content.

Effects of mandibular advancement on supine airway size in normal subjects during sleep.

To examine changes in the upper-airway dimension and its surrounding structures induced by mandibular advancement during sleep. Eleven nonapneic adult males participated in the study. A set of supine lateral cephalograms was taken for each subject at the end of expiration during stage 1 and 2 non-rapid-eye-movement sleep with and without a Klearway appliance (Great Lakes Orthodontics, NY, USA), which was adjusted to 67% of the maximum protrusion position. The Wilcoxon signed-rank test was used to compare changes in the anteroposterior width of the upper airway and the positions of the hyoid bone and third cervical vertebra with and without the appliance. N/A. N/A. N/A. The amount of jaw opening was significantly increased by wearing the titratable oral appliance, and the mandibular symphysis moved backward. The sagittal dimension of the superior pharyngeal airway was significantly increased; however, no significant changes were found in the middle and inferior pharyngeal airway. Significant posterior displacement of the hyoid bone and third cervical vertebra was seen. Moreover, significant inferior displacement of the hyoid bone was also seen. The relationship among the mandibular symphysis, the hyoid bone, and the third cervical vertebra remained constant. Mandibular advancement significantly increases the size of the upper airway in the velopharynx and results in posteroinferior displacement of the hyoid bone and posterior displacement of the third cervical vertebra during sleep.

Changes in mandibular position and upper airway dimension by wearing cervical headgear during sleep.

We previously reported that the wearing of cervical headgear induced forward displacement of the mandible in awake subjects. However, it was unclear whether such mandibular displacement also occurred during sleep. The purpose of this study was to examine changes in mandibular position and oropharyngeal structures that were induced by the wearing of cervical headgear during sleep. Ten healthy adults (7 male and 3 female) who gave their informed consent were included in this study. A pair of lateral cephalograms was taken with the patient in the supine position with and without cervical headgear at end-expiration during stage 1 to 2 non-rapid-eye-movement sleep. The Wilcoxon signed-rank test was used for a statistical analysis. The amount of jaw opening was significantly decreased by the wearing of the cervical headgear (P <.05), although no significant anteroposterior mandibular displacement was induced. The sagittal dimension of the upper airway was significantly reduced (P <.05); however, no significant changes were observed in the vertical length of the upper airway. Although the hyoid bone and the third cervical vertebra moved significantly forward by the wearing of the cervical headgear (P <.05), the relationship among the mandibular symphysis, the hyoid bone, and the third cervical vertebra did not change. These results suggest that cervical headgear significantly reduced the sagittal dimension of the upper airway during sleep, although there was no significant anteroposterior displacement of the mandible.

Supine cephalometric study on sleep-related changes in upper-airway structures in normal subjects.

The purpose of this study was to examine sleep-related changes in the upper airway and surrounding structures including the mandible, hyoid bone, and cervical vertebra in normal subjects using lateral cephalograms in the supine position. Eleven male and nine female healthy adults participated in this study. Supine cephalograms were taken at end-expiration during wakefulness and in stage 1-2 non-rapid-eye-movement (NREM) sleep judged from the electroencephalogram and respiratory monitoring. A paired t-test was used to compare differences between the values measured during wakefulness and sleep. A significant increase in the amount of jaw opening was observed during sleep. The anteroposterior width of the upper airway was significantly decreased during sleep. The distances between the hyoid bone and the mandibular symphysis and between the cervical vertebra and the hyoid bone were significantly decreased during sleep. Consequently, the distance between the cervical vertebra and the mandibular symphysis was significantly decreased. These results suggest that the upper-airway dimension is significantly decreased and relatively small structural changes are induced during sleep in normal subjects.

Articulatory correlates of prosodic control: emotion and emphasis.

This study examines mandibular correlates of prosodic control in nonread dialog exchanges, in which the subject is asked to repeat the same correction of one digit in a three-digit sequence consisting of "five" or "nine" followed by "Pine Street." Articulatory and acoustic data were collected for four speakers of American English at the X-ray Microbeam Facilities at the University of Wisconsin. Jaw opening was measured as vertical jaw position at the time of maximum opening. Middle digits perceived by independent listeners as emphasized generally show jaw opening which is larger than the average jaw opening for the utterances in which they occur. As the speaker repeatedly makes the same correction, not only does jaw opening increase significantly on the corrected digit but also the overall amount of jaw opening on all digits in the corrected exchanges increases. Independent separate perception tests show that listeners also perceive the speakers' answers to be more irritated as the speaker repeats the same correction. The findings suggest a local and global use of the jaw opening gesture to produce both linguistic or paralinguistic and extralinguistic information, that is, word emphasis and the emotional tenor of the dialog itself.

The jaw open-close movements predicted by biomechanical modelling

The aim of this study was to analyse unloaded jaw-opening and jaw-closing movements in humans. For this purpose a dynamical 6-degrees-of-freedom mathematical model of the human masticatory system was developed. It incorporated morphology, muscle architecture and dynamical muscle properties. Various symmetrical jaw-opening and jaw-closing movements were simulated based upon different muscle activation schemes. It was found that the balance between swing and slide of the mandibular condyle at the onset of a jaw-opening movement was predominantly dependent on the level of activation of the digastric and inferior lateral pterygoid museles. The level of activation of the temporalis muscle parts was of critical importance for the jaw-closing movements. The amount of jaw opening was limited by the passive forces of the jaw-closing muscles. In contrast, the influence of the passive forces of the jaw-opening muscles on the jaw-closing movement was neglectable. Throughout the movements the temporomandibular joints remained loaded. The average torques generated by the jaw-opening or jaw-closing muscles with respect to the centre of gravity of the lower jaw had similar orientations and can be considered to be responsible for joint stabilization. The average direction of their lines of action, however, was about opposite, and this can be considered as the major discriminant between a movement in opening or closing direction.

そしゃく運動の機能的分析 正常者における各種食品そしゃく時の経路のパターン

In order to investigate the effect which the consistency of the food has on the masticatory path, 78 normal subjects were asked to chew boiled fish paste, chewing gum, peanuts, and beef jerkey. The path pattern, the amount of opening, and the width of mastication were investigated using an automatic masticatory movement analyzing system, and the following results were obtained.1. The two patterns, pattern I (smooth opening toward the working side, and convex closing) and pattern ifi (opening toward working side after initially toward non-working side and convex closing) constitute the majority of the patterns observed.2. In the group which showed pattern I in chewing boiled fish paste, the most frequent case was pattern I in all other three food.3. In the group which exhibited pattern III in chewing boiled fish paste, the majority cases showed pattern DI in all other three food also.4. The amount of jaw opening and the width of mastication increased with the hardness of the food.5. It is suggested that although the path of mastication varies as the type of food changes from soft to hard, the majority of the path pattern can be represented by patterns I and III in normal subjects. Also, though there are cases which relate pattern I to soft food and pattern III to hard food, basically the consistency of the food does not affect path patterns.

The effect of prior jaw motion on the plot of electromyographic amplitude versus jaw position

Fabrication of interocclusal splint at a thickness determined by the vertical dimension at which the jaw muscle EMG amplitude is minimum has been recommended. However, the effect of prior jaw motion and the effect of the recording site on the EMG amplitudes and on the vertical dimension of minimum EMG activity have not been documented. IEMG amplitudes at various static jaw positions achieved during opening and during closing were analyzed in nine subjects. Surface IEMGs were recorded over the left anterior temporal muscle, left masseter and left suprahyoids muscles, and by nonspecific EMG recording as described by Rugh and Drago. The jaw position was recorded in 5 mm increments by a kinesiograph. After 30 seconds of relaxation, 10 successive IEMG reading at 4-second integration times were obtained at each recording site. These 10 recordings at each requested jaw position were averaged and analyzed. The IEMG activity changed with different jaw position. As the jaw opened from centric occlusion, the IEMG from jaw closing muscles decreased to a minimum and then increased with further opening. Moreover, the IEMG for a particular jaw position differed depending on the history of the jaw movement, that is, whether the position was achieved after an opening step or after a closing step. Two factors, the amount of jaw opening and the history of jaw movement to reach that position, seemed to influence the IEMG differently in each of the recorded muscles.

Mandibular joint control of genioglossus muscle activity in the cat ( Felis domesticus) and monkey ( Macaca irus)

Jaw position had a profound influence on genioglossus (GG) muscle activity, the amount of activity varying with the amount of jaw opening. Mandibular rotations of 21 from tooth contact position increased the GG activity which was maintained as long as the jaw was opened. The response could be abolished by bilateral local anaesthesia of the mandibular joint (MJ). Bipolar stimulation of the small branches of the auriculotemporal nerve which supply the joint elicited a reproducible reflex response in the ipsilateral GG muscle with a latency of approximately 10 ms. The reflex could be abolished by administering a muscle relaxant or by severing or anaesthetizing the branches of the auriculotemporal nerve central to the stimulating electrode. Anaesthetizing or severing the nerves supplying the masseter or temporalis muscles did not abolish the GG reflex response to the nerve stimulus or the response to jaw opening. A prior threshold glossopharyngeal (IX) or superior laryngeal (SL) nerve stimulus produced an early facilitation of the GG reflex elicited by threshold MJ stimulation. In contrast, a supra-threshold lingual, IX or SL nerve stimulus resulted in a long-lasting inhibition of the GG reflex. A number of functional relationships may explain the significance of these excitatory and inhibitory responses in the GG muscle.