Suprahyoid Muscle Activity Research Articles

Relationship between isometric lingual exercise and electromyographic activity of suprahyoid muscles

Relationship between isometric lingual exercise and electromyographic activity of suprahyoid muscles

Contingent negative variations associated with command swallowing in humans

To clarify the role of the cerebral cortex in the swallowing movement, the difference between the waveforms of contingent negative variation (CNV) for the command swallowing and movement-related cortical potential (MRCP) obtained during the volitional swallowing task in humans was investigated. Subjects were instructed to swallow their saliva as quickly as possible in response to a sound signal 4s after the onset of a self-paced breath holding in the command swallowing task or to swallow it while holding their breath for 4s in the volitional swallowing task. CNV and MRCP appeared at five recording areas 1.5 and 2.0s before the onset of the suprahyoid muscle activation determined by the electromyography (EMG) during the command swallowing and volitional swallowing tasks, respectively. The CNV amplitude during the command swallowing task was significantly higher than the MRCP amplitude during the volitional swallowing task (p<0.01). However, the suprahyoid muscle activities during both tasks were not significantly different (p>0.05). These results indicated that CNV may reflect the activities of the prefrontal cortex, in addition to the supplementary motor area, suggesting that the processing of the cue to swallow activates brain areas more widely than the volitional swallowing itself. It is possible to clarify the cognitive functions associated with command swallowing by analyzing CNV.

Effects of food texture and head posture on oropharyngeal swallowing

This study aimed to describe the electromyographic (EMG) activity patterns of the genioglossus (GG) and suprahyoid (SHy) muscles during swallowing. The effects of changes in food texture/consistency and head posture on transport of the swallowed bolus were also investigated. Participants were 10 normal adults. Test foods consisted of a liquid, a syrup, or 4 ml of paste made from 0.5% or 1.0% agar. Each food was swallowed with the head in one of three positions, and EMGs and videofluorographic (VF) images were recorded. Mean values of onset, peak, and offset times, peak amplitude, area, and duration of the EMG burst were measured. The total swallowing time, oral ejection time, pharyngeal transit time, clearance time, fauces transit time, and upper esophageal sphincter (UES) transit time were measured. The GG muscle burst patterns showed two peaks (GG1 and GG2) during each swallowing. The offset time and duration of the GG1 burst and the onset, peak, and offset times and duration of both the GG2 and SHy bursts were significantly affected by food texture. There were no significant differences in bolus transit time among the different experimental conditions. Regression analyses demonstrated significant linear relationships between the tongue tip touching the palate and the peak of the GG1 burst, between passage of the bolus tail at the fauces and offset of the GG1 burst, between passage of the bolus tail at the UES and peak of the GG2 burst, and between passage of the bolus tail at the UES and offset of the SHy burst. These results demonstrate that the duration, but not the amplitude, of tongue and suprahyoid muscle activity were increased with increasing hardness of food during swallowing and that the bolus transit time can be fixed within a certain range of physical food properties.

Influence of food properties and body posture on durations of swallowing‐related muscle activities

The purpose of this study was to determine (i) whether or not textural properties of foods and body positions affect the durations of anterior tongue and suprahyoid muscle activities during swallowing, and (ii) if such changes occur, is the 'pre-peak' or the 'post-peak' duration of integrated muscle activity responsible. We used two test foods with different properties of hardness and adhesiveness. We recorded electromyograms (EMGs) from the anterior tongue and suprahyoid muscles as well as the laryngeal movement associated with swallowing in normal subjects (six men and three women; 21-30-years old). The subjects swallowed the test foods in four randomly set postures: upright, two inclined (60 degrees and 30 degrees to horizontal), and supine. None of the measured durations for the anterior tongue and suprahyoid EMGs were different among the four positions during swallowing of either food. The 'total' duration, from the start to the end of the integrated EMG, of anterior tongue activity was significantly (P<0.001, anova) longer during the swallowing of the tougher and more adhesive food than during swallowing of the other food, but the 'total' duration of suprahyoid activity was unchanged. The 'post-peak' duration of anterior tongue activity, which stretched from the peak to the end of the integrated EMG, was also significantly longer (P<0.001, anova) during swallowing of the tougher and more adhesive food. The results indicate that tougher and more adhesive foods prolong the duration, especially the 'post-peak' duration, of anterior tongue activity during swallowing in the upright, inclined and supine positions.

A Significant Increase in Breathing Amplitude Precedes Sleep Bruxism

Sleep bruxism (SB) is a stereotyped movement disorder that is characterized by rhythmic masticatory muscle activity (RMMA) and tooth grinding. Evidence has suggested that SB is associated with sleep arousals and that most RMMA episodes are preceded by physiologic changes occurring in sequence, namely, a rise in autonomic sympathetic-cardiac activity followed by a rise in the frequency of EEG and suprahyoid muscle activity. In the present study, we hypothesize that an increase in respiration also characterizes the onset of SB within the arousal sequence. Polygraphic sleep recordings of 20 SB subjects without any sleep-related breathing disorders were analyzed for changes in respiration (ie, root mean square, area under the curve, peak, peak-to-peak, and length) extracted from a nasal cannula signal. Variables were analyzed and compared using analysis of variance and correlation tests. Measurements of respiration showed significant changes over time. Four seconds before RMMA muscle activity, the amplitude of respiration is already increased (8 to 23%); the rise is higher at the onset of the suprahyoid activity (60 to 82% 1 s before RMMA); the rise is maximal during RMMA (108 to 206%) followed by a rapid return to levels preceding RMMA. A positive and significant correlation was found between the frequencies of RMMA episodes and the amplitude of breath (R(2) = 0.26; p = 0.02). The amplitude of respiratory changes was 11 times higher when arousal was associated with RMMA in comparison to arousal alone. To our knowledge, this is the first report showing that RMMA-SB muscle activity is associated with a rise in respiration within arousal.

Correspondence between food consistency and suprahyoid muscle activity, tongue pressure, and bolus transit times during the oropharyngeal phase of swallowing

This study aimed to evaluate the effects of food texture and viscosity on the swallowing function by measuring tongue pressure and performing a videofluorographic (VF) examination. Eleven normal adults were recruited for this study. Test foods with different consistencies and liquid contents, i.e., a half-solid nutrient made of 0.8 and 1.5% agar powder, syrup, and a liquid containing 40 wt/vol% barium sulfate, were swallowed, and the anterior (AT) and posterior tongue pressures (PT) and electromyographic (EMG) activity of the suprahyoid muscles were recorded, together with VF images. The timing of each event obtained from EMG, tongue pressure, and VF recordings was measured and then compared. We found that the AT and PT activity patterns were similar and showed a single peak. The peak, area, and time duration of all of the variables for AT and PT and EMG burst increased with increasing hardness of the bolus. The onset of the EMG burst always preceded those of the AT and PT activities, while there were no significant differences in peak and offset times among EMG burst, AT, and PT. Total swallowing time and oral ejection time were significantly longer during the swallowing of 1.5% agar than any other boluses, while pharyngeal transit time and clearance time were significantly longer during the swallowing of syrup, which was as hard as the liquid, but showed a higher viscosity than the liquid. The results suggested that the major effects of food hardness were to delay oral ejection time, which strongly delays total swallowing time. In addition, pharyngeal bolus transit is not dependent on the hardness of food but on its viscosity.

Textural Evaluation of Rice Cake by Chewing and Swallowing Measurements on Human Subjects

The difficulty in masticating and swallowing rice cake was quantified. Healthy subjects ate pieces of rice cake (9 g and 3 g) and a modified product (9 g). We used electromyography to measure the activity of the jaw-closing and -opening muscles during chewing, as well as the suprahyoid muscle activity, laryngeal movement, and sound during swallowing. The smaller the rice cake, the shorter the mastication time, the fewer the number of chews, and the less the jaw-closing muscle activity. A modified rice cake product (9 g) was consumed with less mastication effort than the standard rice cake (9 g) and with the same effort as the standard (3 g). Both the sample amount and texture influenced mastication, although neither factor caused a significant difference in swallowing characteristics. These observations suggest that swallowing was induced when the bolus properties became suitable for swallowing, as healthy subjects could adjust their mastication technique according to the food amount and texture.

Extrinsic tongue and suprahyoid muscle activities during mastication in freely feeding rabbits

To evaluate the coordination of tongue and suprahyoid muscle activities during natural mastication, electromyograms (EMGs) of jaw-closer, jaw-opener, suprahyoid (mylohyoid, MH), tongue-retractor (styloglossus, SG) and tongue-protractor (genioglossus, GG) muscles were recorded as well as the jaw-movement trajectories in vertical and horizontal axes in awake rabbits. Each masticatory cycle had three components including the fast-closing (FC), slow-closing (SC) and opening (Op) phases. The duration of the SC phase was much longer during pellet chewing while the durations of the FC and Op phases were much shorter during pellet chewing than bread or banana chewing. The jaw movements during banana chewing had a small amplitude of lateral excursion and a large amplitude of gape as compared with those during pellet and bread chewing. The MH muscle exhibited double-peaked EMG bursts during the Op phase. The MH bursts in the late part of the Op phase were dominant on the non-chewing side during pellet and bread chewing. The SG muscle also exhibited double-peaked EMG bursts. During pellet and bread chewing, the SG bursts during the SC phase were significantly larger on the chewing side than the non-chewing side. These bursts were also dominant during pellet chewing as compared with banana chewing. There was little difference in the GG bursts between the chewing and non-chewing sides or among the foods. Our results suggest that patterns of the MH and SG muscle activity are affected by the peripheral inputs and/or chewing patterns while those of the GG muscle activity was less modulated regardless of the consistency of foods.

Breathing modes, body positions, and suprahyoid muscle activity.

To determine (1) how electromyographic activities of the genioglossus and geniohyoid muscles can be differentiated, and (2) whether changes in breathing modes and body positions have effects on the genioglossus and geniohyoid muscle activities. Ten normal subjects participated in the study. Electromyographic activities of both the genioglossus and geniohyoid muscles were recorded during nasal and oral breathing, while the subject was in the upright and supine positions. The electromyographic activities of the genioglossus and geniohyoid muscles were compared during jaw opening, swallowing, mandibular advancement, and tongue protrusion. The geniohyoid muscle showed greater electromyographic activity than the genioglossus muscle during maximal jaw opening. In addition, the geniohyoid muscle showed a shorter (P < 0.05) latency compared with the genioglossus muscle. Moreover, the genioglossus muscle activity showed a significant difference among different breathing modes and body positions, while there were no significant differences in the geniohyoid muscle activity. Electromyographic activities from the genioglossus and geniohyoid muscles are successfully differentiated. In addition, it appears that changes in the breathing mode and body position significantly affect the genioglossus muscle activity, but do not affect the geniohyoid muscle activity.

Effect of Wearing Cervical Headgear on Tongue Pressure

The purpose of this study was to examine whether wearing cervical headgear affected tongue pressure on the lingual surface of mandibular incisors, with particular attention to suprahyoid muscle activity. Tongue pressure was recorded using a miniature pressure sensor without cervical headgear and with two cervical headgears with traction forces of 500 and 1200 g, respectively. Electromyographic activity of suprahyoid muscles and respiratory-related movement were recorded simultaneously. Wearing cervical headgear significantly affected tongue pressure and suprahyoid muscle activity in the short-term. A significant increase in tongue pressure was observed in association with an increase in traction force from 500 to 1200 g, whereas no significant difference in suprahyoid muscles activity was seen between these force levels. These results suggest that wearing cervical headgear increases tongue pressure on the lingual surface of mandibular incisors, and this increase in tongue pressure may result from changes in the electromyographic activity of suprahyoid muscles to maintain adequate pharyngeal patency.

Head posture and hyo-mandibular function in man: A synchronized electromyographic and video fluorographic study of the open-close-clench cycle

Synchronized electromyography and videofluorography (lateral projection) were used to investigate the influence of altered head posture on hyo-mandibular movements, suprahyoid muscle length, suprahyoid working angle, and timing of suprahyoid and masseter muscle activity. Twelve adult male subjects with normal dentofacial morphology were investigated during the open-close-clench cycle. Using upright head position (Frankfort horizontal) as reference, several statistically significant observations were made during forward flexion and backward extension of the head. The results indicate that head posture is a significant factor in studies of mandibular and hyoid bone movements, and masseter and suprahyoid muscle function.

Masticatory muscle activity and hyoid bone behavior during cyclic jaw movements in man: A synchronized electromyographic and videofluorographic study

Synchronized electromyography (EMG) and videofluorography were used to relate the EMG activity from the suprahyoid and masseter muscles and the movement of the hyoid bone to different phases of the jaw open-close-clench cycle. The subjects investigated comprised 19 adult males with normal dentofacial appearances. Five subjects were excluded from the analyses because of a uniform suprahyoid EMG pattern during cyclic jaw movements. The results from the remaining fourteen subjects revealed that mandibular opening was preceded by suprahyoid EMG activity and movement of the hyoid bone in an upward-forward direction. During jaw opening and the first half of the jaw-open phase, EMG activity was registered exclusively from the suprahyoid muscles. The hyoid bone was moved downward-backward during jaw opening. Mandibular closing was preceded by masseter EMG activity and movement of the hyoid bone in a further downward-backward direction. During jaw closing the hyoid bone moved upward and forward. Discrete EMG bursts from the suprahyoid muscles were occasionally registered simultaneously with the masseter EMG activity during jaw closing. No absolute reciprocity existed between suprahyoid and masseter muscle activity during cyclic jaw movements. A period of no EMG activity from either the suprahyoid muscle group or the masseter muscle was noted during the jaw-open phase and the occlusal phase.

Head posture and masticatory muscle function. An EMG investigation.

The investigation aimed to determine to what extent head posture affected the EMG activity of the jaw opening (suprahyoid) and jaw closing (masseter) muscles during chewing. The subjects comprised twenty adult males with normal occlusion. The EMG parameters analyzed were: maximal integrated EMG activity; duration, and coordination of jaw opening and closing muscle activity. Recordings were made with the head in three positions: normal upright, inclined forward, and inclined backward. Maximal integrated EMG activity was reduced for the masseter muscle when the head was flexed forward, and for the suprahyoid muscle group when the head was flexed backward. The duration of the masseter chewing phase was reduced when the head was flexed forward and increased when the head was flexed backward. The duration of the suprahyoid chewing phase was unaffected by variation in head position. No absolute reciprocity was found between the suprahyoid and masseter muscle activity during chewing. Suprahyoid overlap at the end of the masseter chewing phase was reduced when the head was flexed forward. The amount of masseter overlap at the end of the suprahyoid chewing phase was unaffected by variation in head position.

Jaw reflexes elicited by electrical stimulation of the hard palate of the rat

Reflex responses of the oral musculature to electrical stimulation of sensory elements in the hard palate were studied in decerebrate rats. Activity in the suprahyoid muscles, the intrinsic and extrinsic tongue muscles and the jaw-closing muscles was recorded electromyographically; at the same time jaw positions were recorded. Muscle group-activity patterns depended on the place of stimulation and the strength of the stimulus. Stimulation of the antemolar region of the palate evoked:—at threshold stimulation, suprahyoid muscle activity (latency 6–7 ms) which did not result in jaw movement; with stimuli about 1.2–1.5 × threshold, enhancement of suprahyoid muscle activity resulting in a transient jaw opening (latency 15 ms, duration 35 ms) sometimes accompanied by tongue reactions (latency 15 ms, duration 5–10 ms); with stimuli about 1.5–3 × threshold, additional jaw-closing muscle reactions (latencies 5–10 ms and 15–20 ms) sometimes changing the transient jaw opening to a transient jaw closing (latency 15 ms, duration 35 ms). Stimulation of the intermolar region evoked:- at threshold stimulation, two bursts of activity in the intrinsic tongue muscles (latencies 15–20 ms and 40–60 ms) and reactions in the jaw-closing muscles (latency 50–80 ms) resulting in a long-lasting jaw closure; with stimuli about 1.2–1.5 × threshold, a gradual shift from the reactions at threshold to a suprahyoid muscle and jaw-closing muscle response of short latency (6–9 ms), causing fast transient jaw opening followed by prolonged jaw closing; with stimuli about 1.5–3 × threshold, only short latency suprahyoid and jaw-closing muscle reactions. The strongest stimuli at this level abolished the jaw-closing reflex and reinforced the jaw-opening reflex. Stimulation of the intermolar region with two equal stimuli (1.2–1.5 × threshold) and several time intervals showed the following reaction pattern:- At very short intervals (1–7 ms), the jaw-closing reflex was suppressed; intervals larger than 6 ms evoked two bursts in the anterior digastric muscles. At about 12-ms intervals, the second reflex disappeared but reappeared at intervals larger than 30–40 ms, being equal to conditioning value at intervals larger than 60 ms. At stimulus intervals up to 200 ms a second stimulus did not produce a second response of the jaw-closing muscles (long-latency closing reflex).

Blink reflexes during sleep and wakefulness in man

Blink reflexes were studied in man during the sleep-wakefulness cycle and in wakefulness in relation to the vigilance level and emotional state. Mono- and polysynaptic responses to electrical stimuli to the supraorbital branch of the Vth nerve were recorded electromyographically from orbicularis oculi. Electrical cerebral activity, eye movement, suprahyoid muscle activity, electrocardiogram and skin resistance were monitored at the same time. 1. a. In relation to the sleep-wakefulness cycle, blink reflexes show a highly significant depression of both early and late responses during synchronized sleep, while during desynchronized sleep only slight depression of the trigeminofacial reflexes is observed. 2. b. The habituation of the polysynaptic component of the blink reflex shows clear modification related to vigilance level and emotional state in wakefulness. Alpha activity and reflex habituation changes are intercorrelated: any increase of vigilance level, sufficient to induce alpha blocking, induces reappearance of polysynaptic responses previously habituated (dishabituation or sensitization). These data reveal the particular functional situation of the reflex arcs controlling the facial muscles supporting mimetic expression (Darwin 1874).

AN ELECTROMYOGRAPHIC STUDY OF THE ACTIVITY OF CERTAIN SUPRAHYOID MUSCLES (MAINLY THE ANTERIOR BELLY OF DIGASTRIC MUSCLE) AND OF THE RECIPROCAL INNERVATION OF THE ELEVATOR AND DEPRESSOR MUSCULATURE OF THE MANDIBLE

AN ELECTROMYOGRAPHIC STUDY OF THE ACTIVITY OF CERTAIN SUPRAHYOID MUSCLES (MAINLY THE ANTERIOR BELLY OF DIGASTRIC MUSCLE) AND OF THE RECIPROCAL INNERVATION OF THE ELEVATOR AND DEPRESSOR MUSCULATURE OF THE MANDIBLE