Levator Veli Research Articles

Measurement of velopharyngeal movements induced by isolated stimulation of levator veli palatini and pharyngeal constrictor muscles.

The levator veli palatini (LVP) and superior pharyngeal constrictor muscles (PC) close the velopharynx. However, for the velopharyngeal movements to be understood in detail, each muscle contraction must be analyzed precisely. This study was performed to clarify the velopharyngeal movement which was induced by a single muscle contraction, LVP or PC. Using a nasopharyngeal fiberscope, we analyzed the velopharyngeal movement associated with the contraction of the LVP and PC muscles in mongrel dogs. To elicit the maximal contraction of each muscle, we applied repetitive electrical stimulation to each peripheral nerve efferent to the LVP or PC muscle. Stimulation with a frequency of 77 Hz and 83 Hz induced maximal tension in the LVP and PC muscles, respectively, in isometric contraction. In a second series of experiments, fiberscopic views of the velopharyngeal movements associated with each muscle's maximal contraction were recorded. The degree of closure was calculated at several sections. The LVP muscle pulled the caudal fourth of the soft palate, while the PC projected the posterior wall at the level of the caudal end of the soft palate. The PC muscle also projected the lateral wall of the velopharynx. The effect of LVP contraction on the lateral wall was very small. These results show that the velopharyngeal movement associated with LVP contraction is very different from that with PC contraction.

Effect of temporary closure of oronasal fistulae on levator veli palatini muscle activity.

The objective of this study was to clarify electromyographically the effects of closing an oronasal fistula on levator muscle activity and oral air pressure in patients with velopharyngeal incompetence and in those with adequate velopharyngeal function. Five patients with adequate velopharyngeal function and six patients with velopharyngeal incompetence were studied. All subjects had an oronasal fistula at the anterior third portion of the hard palate in spite of primary palatal closure using palatal push-back operation. The smoothed electromyographic activity of the levator veli palatini muscle was measured with the fistula closed with a cotton swab dipped in saline and with the fistula left open. Under the closed fistula condition, oral air pressure was greater than that observed under the open fistula condition irrespective of velopharyngeal function. Levator veli palatini muscle activity was significantly lower in magnitude under the condition of closure than under the open condition in the patients with adequate velopharyngeal function, whereas in those with velopharyngeal incompetence, it was not significantly changed. The results suggest that velopharyngeal function is affected by temporary closure of an oronasal fistula, and that the magnitude of the effect is greater for subjects with adequate velopharyngeal function than for subjects with velopharyngeal incompetence.

Effect of Temporary Closure of Oronasal Fistulae on Levator Veli Palatini Muscle Activity

Effect of Temporary Closure of Oronasal Fistulae on Levator Veli Palatini Muscle Activity

Activities of superior pharyngeal constrictor and levator veli palatini muscles related to respiration in dogs.

This study, using mongrel dogs, attempted to delineate the respiratory activity of two closure muscles of the velopharynx, the levator veli palatini (LVP) and superior pharyngeal constrictor (PC) muscles. Fifteen mongrel dogs were given tracheotomies, with intratracheal tubes being connected to their respiratory circuits. Activities of the PC and LVP muscles were recorded electromyographically, and the effects of PaO2 and PaCO2 were analyzed along with the effects of lung inflation intratracheally with O2 and N2. Under hypoxic conditions, expiratory LVP activity was observed while PC activity diminished. The effects of lung inflation on both LVP and PC activities were also studied. The activities of both muscles were enhanced by lung inflation. It was thus suggested that the roles of both muscles during velopharyngeal closing movements are not the same.

Activities of Superior Pharyngeal Constrictor and Levator Veli Palatini Muscles Related to Respiration in Dogs

This study, using mongrel dogs, attempted to delineate the respiratory activity of two closure muscles of the velopharynx, the levator veli palatini (LVP) and superior pharyngeal constrictor (PC) muscles.Fifteen mongrel dogs were given tracheotomies, with intratracheal tubes being connected to their respiratory circuits. Activities of the PC and LVP muscles were recorded electromyographically, and the effects of PaO2 and PaCO2 were analyzed along with the effects of lung inflation intratracheally with O2 and N2.Under hypoxic conditions, expiratory LVP activity was observed while PC activity diminished. The effects of lung inflation on both LVP and PC activities were also studied. The activities of both muscles were enhanced by lung inflation.It was thus suggested that the roles of both muscles during velopharyngeal closing movements are not the same.

Rapid magnetic resonance imaging for assessment of velopharyngeal muscle movement on phonation

The levator veli palatini muscle is the most important muscle for velopharyngeal (VP) closure in speech. I-3 Patients with speech abnormalities related to cleft palate are treated by reconstruction to achieve normal muscle realignment; however, in patients with abnormal speech related to cleft or noncleft palate, the structure and dynamic movement of the levator veli palatini muscle are unable to be observed by methods such as roentgenography, videofluoroscopy, and nasopharyngoscopy, which are used to evaluate the appearance of overall pharyngeal movement. Recently, rapid magnetic resonance imaging (MRI) has been developed, which permits the imaging of 5 slices within 14 seconds. Using it, we could obtain clear sequence images of the levator muscle sling itself during phonation. The purpose of this article is to present the possibility of assessment of the dynamics of VP closure associated with the levator muscle. MRI was performed as follows: The machine was a superconductive

Respiratory function of velopharyngeal constrictor muscles during wakefulness in normal adults.

The levator veli palatini (LVP) and the superior pharyngeal constrictor (SPC) influence velopharyngeal patency and soft palate position, but their behavior during respiration is incompletely characterized. To further clarify their respiratory function, we recorded electromyographic activity (EMG) in the LVP and the SPC in awake normal subjects breathing orally. EMG data were obtained in six subjects for the LVP and in nine subjects for the SPC. EMG activity and timing and ventilation were measured during isocapnic hypoxia and hyperoxic hypercapnia. Phasic EMG activity was inconsistently present during unstimulated oral breathing. Timing of EMG phasic activity was variable for both muscles. Peak LVP activity was mainly or exclusively expiratory in three of six subjects. Peak SPC activity was mainly or exclusively expiratory in five of nine subjects. With chemostimulation, recruitment of phasic activity was observed in the LVP and in four of six subjects and in the SPC in five of nine subjects. Tonic activity increased in four of six subjects for the LVP and in three of nine subjects for the SPC. However, the response was alinear, and intersubject as well as breath-to-breath variability was substantial. In conclusion, LVP and SPC are characterized by the higher inter- and intrasubject variability of EMG activity, timing of activation, and response to chemostimulation.

Effect of Speech Appliance on Levator Veli Palatini Muscle Activity during Speech

Effect of Speech Appliance on Levator Veli Palatini Muscle Activity during Speech

Reflex Responses of Levator Veli Palatini Muscle in Decerebrated Cats

Reflex Responses of Levator Veli Palatini Muscle in Decerebrated Cats

Roles of the levator veli palatini and the superior pharyngeal constrictor muscles in velopharyngeal closure during deglutition in the dog

Roles of the levator veli palatini and the superior pharyngeal constrictor muscles in velopharyngeal closure during deglutition in the dog

Coordination Between Palatal and Laryngeal Muscle Activities in Response to Rebreathing and Lung Inflation

The soft palate and larynx play an important role in respiration and phonation, regulating the airflow in the upper airway. The levator veli palatini muscle (LVP) is the principal muscle responsible for generating palatal movements. The lateral cricoarytenoid muscle (LCA) is a laryngeal adductor muscle, and the posterior cricoarytenoid muscle (PCA) is a laryngeal abductor muscle. This study was designed to define, by electromyographic techniques, the coordination between palatal and laryngeal muscle activities in response to rebreathing and lung inflation. We performed tracheotomies on 12 mongrel dogs anesthetized with sodium pentobarbital and compared the effects of rebreathing and lung inflation on LVP activities with those on LCA and PCA activities. During rebreathing, expiratory LVP and inspiratory PCA activities were progressively augmented, but expiratory LCA activity was inhibited. On the other hand, lung inflation caused augmentation of LVP and LCA activities. In contrast, lung inflation inhibited PCA activity. We thus concluded that LVP activity coordinates with PCA activity in response to alternation of Paco2 and Pao2 levels, while it coordinates with LCA activity in response to lung inflation.

Coordination between palatal and laryngeal muscle activities in response to rebreathing and lung inflation.

The soft palate and larynx play an important role in respiration and phonation, regulating the airflow in the upper airway. The levator veli palatini muscle (LVP) is the principal muscle responsible for generating palatal movements. The lateral cricoarytenoid muscle (LCA) is a laryngeal adductor muscle, and the posterior cricoarytenoid muscle (PCA) is a laryngeal abductor muscle. This study was designed to define, by electromyographic techniques, the coordination between palatal and laryngeal muscle activities in response to rebreathing and lung inflation. We performed tracheotomies on 12 mongrel dogs anesthetized with sodium pentobarbital and compared the effects of rebreathing and lung inflation on LVP activities with those on LCA and PCA activities. During rebreathing, expiratory LVP and inspiratory PCA activities were progressively augmented, but expiratory LCA activity was inhibited. On the other hand, lung inflation caused augmentation of LVP and LCA activities. In contrast, lung inflation inhibited PCA activity. We thus concluded that LVP activity coordinates with PCA activity in response to alternation of Paco2 and Pao2 levels, while it coordinates with LCA activity in response to lung inflation.

Surgical procedures for functional improvement of the velum

The purpose of this study was to investigate the functional differences between the lateral walls of the mesopharynx and the epipharynx during speech. Endoscopic and electromyographic techniques were used to demonstrate the movement patterns of these two different levels of the pharyngeal wall and activities of the muscles which were supposed to induce these movements.From the movement date, it was concluded that the epipharyngeal wall contributed to the velopharyngeal closure and the mesopharyngeal wall to the vowl articulation.Electromyographic data clearly showed that the levator veli palatini muscle induced the horizontal movement of the epipharyngeal wall as well as the vertical movement of the velum. On the other hand, the superior constrictor muscle appeared to behave as one of the responsible muscles for the medial displacement of the mesopharyngeal wall.

Simultaneous carboplatin and radiation therapy in oral squamous cell carcinoma

The purpose of this study was to investigate the functional differences between the lateral walls of the mesopharynx and the epipharynx during speech. Endoscopic and electromyographic techniques were used to demonstrate the movement patterns of these two different levels of the pharyngeal wall and activities of the muscles which were supposed to induce these movements.From the movement date, it was concluded that the epipharyngeal wall contributed to the velopharyngeal closure and the mesopharyngeal wall to the vowl articulation.Electromyographic data clearly showed that the levator veli palatini muscle induced the horizontal movement of the epipharyngeal wall as well as the vertical movement of the velum. On the other hand, the superior constrictor muscle appeared to behave as one of the responsible muscles for the medial displacement of the mesopharyngeal wall.

Observation of velopharyngeal closure patterns following isolated stimulation of levator veli palatini and pharyngeal constrictor muscles.

This study, using mongrel dogs, showed the individual movements caused by the levator veli palatini muscle (LVP) and pharyngeal constrictor (PC) contraction, induced by electrical stimulation to each peripheral motor nerve. Each bilateral peripheral motor nerve of the LVP and PC muscles was isolated and stimulated electrically to induce the individual contraction of bilateral LVP and PC muscles. The movements were visualized by use of a fiberscope. Vertical movement of the middle soft palate was observed mainly at LVP contraction. Circular closure in the posterior region of the velopharynx was induced by contraction of the PC muscle. The posterior and lateral wall movements clearly occurred following PC contraction.

Observation of Velopharyngeal Closure Patterns Following Isolated Stimulation of Levator Veli Palatini and Pharyngeal Constrictor Muscles

This study, using mongrel dogs, showed the individual movements caused by the levator veli palatini muscle (LVP) and pharyngeal constrictor (PC) contraction, induced by electrical stimulation to each peripheral motor nerve. Each bilateral peripheral motor nerve of the LVP and PC muscles was isolated and stimulated electrically to induce the individual contraction of bilateral LVP and PC muscles. The movements were visualized by use of a fiberscope. Vertical movement of the middle soft palate was observed mainly at LVP contraction. Circular closure in the posterior region of the velopharynx was induced by contraction of the PC muscle. The posterior and lateral wall movements clearly occurred following PC contraction.

Proprioceptive representation of the levator veli palatini muscle in the solitary nucleus of the rat.

The levator veli palatini muscle is innervated by motoneurons of the glossopharyngeal nerve, which are located within the ambiguus nucleus; however, little is known about the afferent fibers of this muscle. A horseradish peroxidase study was conducted in rats following injection into the levator veli palatini muscle branch to reveal the location and the distribution of dendrites of the afferent fibers of the muscle. Terminal labels were densely distributed in the lateral region of the solitary nucleus, which receives afferents of the glossopharyngeal nerve, ipsilateral and contralateral to the injection site. The relationship of the levator veli palatini muscle with respiration was suggested by the localization of labeled terminals at sites where the afferents from the respiratory organs project densely, and by the demonstrated proprioceptive role of the afferent fibers passing through the muscle spindles contained in the levator veli palatini muscle.

Proprioceptive Representation of the Levator Veli Palatini Muscle in the Solitary Nucleus of the Rat

Proprioceptive Representation of the Levator Veli Palatini Muscle in the Solitary Nucleus of the Rat

Effect of Nasal Air Flow Rate and Oral Air Pressure on Levator Veli Palatini Muscle Activity in Normal Speakers

Effect of Nasal Air Flow Rate and Oral Air Pressure on Levator Veli Palatini Muscle Activity in Normal Speakers

Effect of Speech Appliance in Place on Levator Veli Palatini Muscle Activity during Blowing

Effect of Speech Appliance in Place on Levator Veli Palatini Muscle Activity during Blowing