Head rotation improves airway obstruction, especially in patients with less severe obstructive sleep apnea without oropharyngeal collapse.

PURPOSE: Head rotation is thought to have an effect on obstructive sleep apnea (OSA) severity. However, keeping the head rotated fully during sleep is difficult to maintain, and the effect of head rotation is not the same in all OSA patients. Thus, this study aimed to identify whether less head rotation has an effect on airway patency and determine the responder characteristics to the head rotation maneuver (HRM). METHODS: We recruited 221 patients who underwent overnight polysomnography and drug-induced sleep endoscopy (DISE) in a tertiary hospital from June 2019 to July 2020. Airway patency and the site of airway collapse were determined in the supine position with the head at 0, 30, and 60 degrees of rotation (HRM0°, HRM30°, and HRM60°, respectively) during DISE. The site of collapse was determined using the VOTE classification system: the velum (palate), oropharyngeal lateral walls, tongue base, and epiglottis. Each structure was labeled as 0, 1, or 2 (patent, partially obstructed, and completely obstructed, respectively). Airway response to the HRM30° and 60° and the clinical characteristics associated with airway opening were analyzed. RESULTS: The study population had a median age of 52 (25-61) years, a body mass index of 26.7(24.6-29.4) kg/m2, and the apnea-hypopnea index (AHI) of 28.2(13.7-71.9) events/h. HRM influenced airway patency positively not only with HRM60° (p<0.001) but also following limited rotation (HRM30°, p<0.001). Patients with tongue base (40.0% with HRM 60°) and epiglottic (52.6% with HRM 60°) collapse responded particularly well to HRM. Multivariate analysis revealed that lower AHI (p<0.001) and an absence of oropharyngeal lateral walls collapse (p = 0.011) were significant predictors of responders to HRM. CONCLUSION: Head rotation improved airway obstruction in OSA patients, even with a small degree of rotation, and should be further explored as a potential form of therapy in appropriately selected patients.

Postoperative Skeletal Stability and Pharyngeal Airway: Counterclockwise versus Clockwise Rotation during Mandibular Setback Surgery.

PURPOSE: To compare the effects of counterclockwise rotation (CCR) and clockwise rotation (CR) of the mandible on the pharyngeal airway during mandibular setback surgery. Materials and Methods. Serial cephalograms of 40 patients with mandibular prognathism, including 20 who underwent CCR and 20 who underwent CR, were taken at the following time intervals: preoperatively (T1), immediately postoperatively (T2), >1 year after surgery (T3), final surgical changes (T31), postoperative stability (T32), and immediate surgical change (T21). Changes in menton (Me) and hyoid (H) positions, soft palate width, soft palate length, soft palate angle and craniovertebral angle (C2C4-SN), and pharyngeal airway spaces (nasal pharyngeal airway (NOP), uvula pharyngeal airway (UOP), tongue pharyngeal airway (TOP), and epiglottis pharyngeal airway (EOP)) were evaluated. RESULTS: The mean Me (T31) setback for CCR and CR was 12.56 and 13.06 mm, respectively, with 2.41 mm upward and 3.29 mm downward, respectively. The vertical Me position of CR exhibited significant downward movement compared with that of CCR. The mean H setback results for CCR and CR were 4.42 and 5.75 mm, respectively, with 1.47 mm downward and 2.97 mm downward, respectively. The C4C2-SN angles for CCR and CR increased by 2.68° and 3.65°, respectively, whereas their palatal angles increased by 2.35° and 5.25°, respectively. Pearson's correlation analysis (T31) revealed that for CCR, no pharyngeal airway spaces were significantly correlated with any measured variables. In CR, NOP was significantly correlated (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (r = 0.58) with the vertical Me position. Significant relapse (T32) was observed after CR in the horizontal (. CONCLUSION: Pharyngeal airway space narrowed postoperatively, and its patency was appropriately maintained through natural physiological regulation of the craniovertebral angle (C2C4-SN). Significant postoperative relapse was correlated with CR.

Effects of Angle of Epiglottis on Aerodynamic and Acoustic Parameters in Excised Canine Larynges.

OBJECTIVES: The aim of this study is to explore the effects of the angle of epiglottis (Aepi) on phonation and resonance in excised canine larynges. METHODS: The anatomic Aepi was measured for 14 excised canine larynges as a control. Then, the Aepis were manually adjusted to 60° and 90° in each larynx. Aerodynamic and acoustic parameters, including mean flow rate, sound pressure level, jitter, shimmer, fundamental frequency (F0), and formants (F1'-F4'), were measured with a subglottal pressure of 1.5 kPa. Simple linear regression analysis between acoustic and aerodynamic parameters and the Aepi of the control was performed, and an analysis of variance comparing the acoustic and aerodynamic parameters of the three treatments was carried out. RESULTS: The results of the study are as follows: (1) the larynges with larger anatomic Aepi had significantly lower jitter, shimmer, formant 1, and formant 2; (2) phonation threshold flow was significantly different for the three treatments; and (3) mean flow rate and sound pressure level were significantly different between the 60° and the 90° treatments of the 14 larynges. CONCLUSIONS: The Aepi was proposed for the first time in this study. The Aepi plays an important role in phonation and resonance of excised canine larynges.

Is there a threshold that triggers cortical arousals in obstructive sleep apnea.

STUDY OBJECTIVES: To determine whether there is a consistent epiglottic pressure value that predicts respiratory arousal from sleep. METHODS: Thirty-one patients with obstructive sleep apnea underwent overnight polysomnography while instrumented with an epiglottic catheter to measure airway pressures. Nadir epiglottic pressures during respiration events (obstructive apneas/hypopneas) terminated with or without arousals were compared. The events were selected by two methods, (1) 20 events with/without arousals were randomly selected, and (2) Events were sampled in pairs (one terminated with arousal and one without arousal) to minimize the effect of sleep duration/stage on the measurement. RESULTS: A total of 1,317 respiratory events were analyzed. There was substantial variability in nadir epiglottic pressure within an individual and among different individuals. The average pressure of 20 randomly selected events with arousals was (-21.2 ± 11.2, ranged -6.68 to -63.34 cm H2O). The nadir epiglottic pressure during respiratory events in NREM stage 2 sleep terminated with arousals was more negative compared with those terminated without arousals using both sampling methods (-23.5 vs. -18.5 cm H2O, p = 0.007 and -20.3 vs. -16.3 cm H2O, p < 0.001). CONCLUSIONS: There were very different levels of epiglottic pressures that preceded arousals within and among individuals. However, cortical arousals are associated with a level of more negative epiglottic pressure compared to events terminated without arousal, findings which support the concept of a respiratory arousal threshold. CLINICAL TRIAL REGISTRATION: The study used existing data to study methodology (from clinical trial "The Impact of Arousal Threshold in Obstructive Sleep Apnea" https://clinicaltrials.gov/show/NCT02264353) and it is not a clinical trial.

Laryngeal closure impedes non-invasive ventilation at birth.

BACKGROUND: Non-invasive ventilation is sometimes unable to provide the respiratory needs of very premature infants in the delivery room. While airway obstruction is thought to be the main problem, the site of obstruction is unknown. We investigated whether closure of the larynx and epiglottis is a major site of airway obstruction. METHODS: We used phase contrast X-ray imaging to visualise laryngeal function in spontaneously breathing premature rabbits immediately after birth and at approximately 1 hour after birth. Non-invasive respiratory support was applied via a facemask and images were analysed to determine the percentage of the time the glottis and the epiglottis were open. HYPOTHESIS: Immediately after birth, the larynx is predominantly closed, only opening briefly during a breath, making non-invasive intermittent positive pressure ventilation (iPPV) ineffective, whereas after lung aeration, the larynx is predominantly open allowing non-invasive iPPV to ventilate the lung. RESULTS: The larynx and epiglottis were predominantly closed (open 25.5%±1.1% and 17.1%±1.6% of the time, respectively) in pups with unaerated lungs and unstable breathing patterns immediately after birth. In contrast, the larynx and the epiglottis were mostly open (90.5%±1.9% and 72.3%±2.3% of the time, respectively) in pups with aerated lungs and stable breathing patterns irrespective of time after birth. CONCLUSION: Laryngeal closure impedes non-invasive iPPV at birth and may reduce the effectiveness of non-invasive respiratory support in premature infants immediately after birth.

Numerical simulation of interaction between organs and food bolus during swallowing and aspiration.

The mechanism of swallowing is still not fully understood, because the process of swallowing is a rapid and complex interaction among several involved organs and the food bolus. In this work, with the aim of studying swallowing and aspiration processes noninvasively and systematically, a computer simulation method for analyzing the involved organs and water (considered as the food bolus) is proposed. The shape and motion of the organs involved in swallowing are modeled in the same way as in our previous study, by using the Hamiltonian moving particle simulation (MPS) method and forced displacements on the basis of motion in a healthy volunteer. The bolus flow is simulated using the explicit MPS method for fluid analysis. The interaction between the organs and the bolus is analyzed using a fluid-structure coupling scheme. To validate the proposed method, the behavior of the simulated bolus flow is compared qualitatively and quantitatively with corresponding medical images. In addition to the healthy motion model, disorder motion models are constructed for reproducing the aspiration phenomenon by computer simulation. The behaviors of the organs and the bolus considered as the food bolus in the healthy and disorder motion models are compared for evaluating the mechanism of aspiration.

Characterization of Swallowing Sound: Preliminary Investigation of Normal Subjects.

OBJECTIVE: The purpose of this study was to characterize the swallowing sound and identify the process of sound generation during swallowing in young healthy adults. METHODS: Thirty-three healthy volunteers were enrolled and allocated into three experimental groups. In experiment 1, a microphone was attached to one of eight cervical sites in 20 subjects, participants swallowed 5 ml water, and the sound waveform was recorded. In experiment 2, 10 subjects swallowed either 0, 5, 10, or 15 ml water during audio recording. In addition, participants consumed the 5 ml bolus in two different cervical postures. In experiment 3, the sound waveform and videofluoroscopy were simultaneously recorded while the three participants consumed 5 ml iopamidol solution. The duration and peak intensity ratio of the waveform were analyzed in all experimental groups. RESULTS: The acoustic analysis of the waveforms and videofluoroscopy suggested that the swallowing sound could be divided into three periods, each associated with a stage of the swallowing movement: the oral phase comprising posterior tongue and hyoid bone movement; the pharyngeal phase comprising larynx movement, hyoid bone elevation, epiglottis closure, and passage of the bolus through the esophagus orifice; and the repositioning phase comprising the return of the hyoid bone and larynx to their resting positions, and reopening of the epiglottis. CONCLUSION: Acoustic analysis of swallowing sounds and videofluoroscopy suggests that the swallowing sound could be divided into three periods associated with each process of the swallowing movement: the oral phase comprising the posterior movement of the tongue and hyoid bone; the pharyngeal phase comprising the laryngeal movement, hyoid bone elevation, epiglottis closure, and the bolus passage to the esophagus orifice; and the repositioning phase comprising the repositioning of the hyoid bone and larynx, and reopening of the epiglottis.

Development and validation of a computational finite element model of the rabbit upper airway: simulations of mandibular advancement and tracheal displacement.

The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for individually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics.

High-speed imaging using rigid laryngoscopy for the analysis of register transitions in professional operatic tenors.

INTRODUCTION: Vocal fold oscillation patterns in tenors singing at high pitches (stage voice above the passaggio) are not yet understood in detail. MATERIALS AND METHODS: Nine professional opera tenors performed a transition from modal register (220 Hz) to falsetto or stage voice above the passaggio (440 Hz) on an /i/ vowel. High-speed digital imaging was performed using a rigid laryngoscopic system with a frame rate of 4,000 frames per second. RESULTS: During the transition to stage voice above the passaggio seven out of nine tenors exhibited a strong retraction of the epiglottis with rising F0, which prevented further analysis of vocal fold oscillations. During transitions to falsetto many supraglottic modifications were also observed. CONCLUSION: Tenor stage voice above the passaggio seems to be typically associated with retraction of the epiglottis for the vowel /i/ thus preventing examination of vocal fold oscillations using rigid laryngoscopy.

Kinematic analysis of swallowing in the patients with esophagectomy for esophageal cancer.

The aim of this study is to reveal the mechanism of esophagectomy-mediated swallowing motion disorders. Forty-seven patients who underwent 3-stage esophagectomy with cervical anastomosis and VFSS for esophageal cancer were selected. Twenty-three patients displayed subglottic aspiration (aspiration group) and the other 24 patients did not show any aspiration or penetration in the videofluoroscopic swallowing study after esophagectomy (no aspiration group). For comparison, 27 healthy volunteers (normal group) were included. Maximal anterior displacement of the hyoid (MADH), maximal superior displacement of the hyoid (MSDH), maximal rotation of the epiglottis (MRE) and pharyngeal delay time (PDT) were measured by image J software. MADH, MRE, and PDT in normal group were significantly different from those in aspiration and no aspiration groups (P<0.001). The normal group displayed a significantly different PDT compared to the no aspiration and aspiration groups, and the no aspiration group had a significantly different PDT compared to the aspiration group (P<0.001). The mechanism of swallowing motion disorders caused by the esophagectomy in esophageal cancer includes the decreased anterior movement of the hyoid and rotation of the epiglottis caused by the prolonged operation time and delayed pharyngeal reflex caused by the laryngeal sensory disturbance. Among them, the main mechanism of subglottic aspiration after esophagectomy is the delayed pharyngeal reflex.

Effortful swallow enhances vertical hyolaryngeal movement and prolongs duration after maximal excursion.

Effortful swallowing (EFS) is a common compensatory swallowing manoeuver for dysphagia patients. We investigated the influence of EFS on temporal and spatial characteristics of the movements of the hyoid bone, larynx and epiglottis in healthy subjects. A total of 41 volunteers swallowed 10 mL of diluted barium solution using two swallowing strategies: usual and effortful swallowing (USS and EFS). The motions of the hyoid bone, larynx and epiglottis were tracked using frame-by-frame kinematic motion analysis of videofluoroscopic images. Maximal velocities and maximal displacements of hyoid and larynx, the maximal angle of the epiglottic tilt, and the durations of hyoid excursion, laryngeal elevation and epiglottic tilt were measured. Compared to USS, EFS was associated with significantly greater vertical displacement of the hyoid (P < 0.001), vertical and horizontal displacement of the larynx (P = 0.003, P = 0.019), and maximal angle of the epiglottic tilt (P = 0.001). In addition, the durations of the vertical and horizontal excursions of the hyoid, vertical excursion of the larynx and the epiglottic tilt were greater in EFS, compared with USS. Effortful swallowing was also associated with significantly greater maximum velocities of the hyoid and larynx during swallowing. In conclusion, the EFS manoeuver facilitates vertical speed and distance of hyolaryngeal excursion and epiglottic tilt and extends the duration of excursion and the epiglottic tilt, especially after reaching maximal excursion in healthy subjects. These results confirm the temporal and kinematic benefits of airway protection induced by the EFS manoeuver.

Peripharyngeal tissue deformation, stress distributions, and hyoid bone movement in response to mandibular advancement.

Mandibular advancement (MA) increases upper airway (UA) patency and decreases collapsibility. Furthermore, MA displaces the hyoid bone in a cranial-anterior direction, which may contribute to MA-associated UA improvements via redistribution of peripharyngeal tissue stresses (extraluminal tissue pressure, ETP). In the present study, we examined effects of MA on ETP distributions, deformation of the peripharyngeal tissue surface (UA geometry), and hyoid bone position. We studied 13 supine, anesthetized, tracheostomized, spontaneously breathing adult male New Zealand White rabbits. Graded MA was applied from 0 to ∼4.5 mm. ETP was measured at six locations distributed throughout three UA regions: tongue, hyoid, and epiglottis. Axial computed tomography images of the UA (nasal choanae to glottis) were acquired and used to measure lumen geometry (UA length; regional cross-sectional area) and hyoid displacement. MA resulted in nonuniform decreases in ETP (greatest at tongue region), ranging from -0.11 (-0.15 to -0.06) to -0.82 (-1.09 to -0.54) cmH2O/mm MA [linear mixed-effects model slope (95% confidence interval)], across all sites. UA length decreased by -0.5 (-0.8 to -0.2) %/mm accompanied by nonuniform increases in cross-sectional area (greatest at hyoid region) ranging from 7.5 (3.6-11.4) to 18.7 (14.9-22.5) %/mm. The hyoid bone was displaced in a cranial-anterior direction by 0.42 (0.36-0.44) mm/mm MA. In summary, MA results in nonuniform changes in peripharyngeal tissue pressure distributions and lumen geometry. Displacement of the hyoid bone with MA may play a pivotal role in redistributing applied MA loads, thus modifying tissue stress/deformation distributions and determining resultant UA geometry outcomes.

Afferent nerve ending density in the human laryngeal mucosa: potential implications on endoscopic evaluation of laryngeal sensitivity.

Laryngeal sensitivity is crucial for maintaining safe swallowing, thus avoiding silent aspiration. The sensitivity test, carried out by fiberoptic endoscopic examination of swallowing, plays an important role in the assessment of dysphagic patients. The ventricular folds appear to be more sensitive than the epiglottis during the sensitivity test. Therefore, this study aimed to investigate the mechanical sensitivity of the supraglottic larynx. In seven healthy adults undergoing microlaryngoscopy to remove vocal cord polyps, we excised mucosal samples from the epiglottis and ventricular folds. We measured afferent nerve fiber density by immunoelectron microscopy. All of the subjects underwent an endoscopic sensitivity test based on lightly touching the laryngeal surface of the epiglottis and ventricular folds. The discomfort level was self-rated by the subjects on the visual analog scale. Samples were fixed and stored in cryoprotectant solution at 4 °C. Sections were stained with the protein gene product 9.5, a pan-neuronal selective marker. Nerve fiber density was calculated as the number of fibers per millimeter length of section. The mean nerve fiber density was higher in ventricular samples than in epiglottis samples (2.96 ± 2.05 vs 0.83 ± 0.51; two-sided p = 0.018). The mean visual analog scale scores were significantly higher for touching the ventricular folds than for touching the epiglottis (8.28 ± 1.11 vs 4.14 ± 1.21; two-sided p = 0.017). The higher sensitivity of the ventricular region should be considered for further refining clinical endoscopic evaluation of laryngeal sensitivity.

Correlation varies with different time lags between the motions of the hyoid bone, epiglottis, and larynx during swallowing.

Although coordination and timing of swallowing have often been investigated by using discrete timing events such as the onset, peak, and duration of specific motions, the sequence and duration of swallowing events cannot represent the coordination of the swallowing mechanism quantitatively. This study aimed to apply a cross-correlation analysis of the motions of the hyolaryngeal structures during swallowing as an objective method for measuring the coordination and timing of the motions. Forty healthy subjects swallowed 2 and 5 ml of diluted barium solution (35 %) and 5 ml of curd yogurt under videofluoroscopy. Hyolaryngeal motions in videofluoroscopic images were digitized using the motion analysis system. The time series of the horizontal and vertical hyoid motion, the laryngeal elevation, and the angle of the epiglottic tilt were analyzed using cross-correlation at each 1/60-s time lag. The results showed high and consistent cross-correlations between hyolaryngeal motions during swallowing in most of the subjects regardless of age and bolus type. The horizontal hyoid motion and laryngeal elevation were more strongly correlated with the epiglottic tilt than the vertical hyoid motion, which might suggest the mechanism of the epiglottic tilt during swallowing. The bolus volume and viscosity affected the correlation coefficients and time lags between the hyolaryngeal motions, particularly those related to the epiglottic tilt. The results suggest that cross-correlation analysis may be used for measuring the coordination and timing of swallowing. Further studies using cross-correlation analysis of additional physiological factors related to swallowing or pathological conditions are warranted.

[The role of the hyoid bone during the swallowing process].

The main purpose of this paper was to review the role of the hyoid movement in the swallowing process and the effect of swallowing posture, age, gender, bolus properties on the hyoid movement. The displacement of the hyoid bone was divided into vertical and forward displacement. The vertical displacement of the hyoid bone contributes primarily to epiglottic and laryngeal closure, while the anterior displacement contributes primarily to opening of the UES. The dysphagia patients often experienced a reduction in hyoid bone displacement. Therefore, further research on the movement of the hyoid bone in the deglutition, especially the relationship between anterior displacement and UES opening is necessary.

Pharyngeal diameter in various head and neck positions during exercise in sport horses.

BACKGROUND: In equine athletes, dynamic stenotic disorders of the upper airways are often the cause for abnormal respiratory noises and/or poor performance. There are hypotheses, that head and neck flexion may influence the morphology and function of the upper airway and thus could even induce or deteriorate disorders of the upper respiratory tract. Especially the pharynx, without osseous or cartilaginous support is prone to changes in pressure and airflow during exercise. The objective of this study was to develop a method for measuring the pharyngeal diameter in horses during exercise, in order to analyse whether a change of head-neck position may have an impact on the pharyngeal diameter. RESULTS: Under the assumption that the width of the epiglottis remains constant in healthy horses, the newly developed method for calculating the pharyngeal diameter in horses during exercise is unsusceptible against changes of the viewing-angle and distance between the endoscope and the structures, which are to be assessed. The quotient of the width of the epiglottis and the perpendicular from a fixed point on the dorsal pharynx to the epiglottis could be used to determine the pharyngeal diameter. The percentage change of this quotient (pharynx-epiglottis-ratio; PE-ratio) in the unrestrained head-neck position against the reference position was significantly larger than that of any other combination of the head-neck positions investigated. A relation between the percentage change in PE-ratio and the degree of head and neck flexion could not be confirmed. CONCLUSIONS: It could be shown, that the pharyngeal diameter is reduced through the contact position implemented by the rider in comparison to the unrestrained head and neck position. An alteration of the pharyngeal diameter depending on the degree of head and neck flexion (represented by ground and withers angle) could not be confirmed.

Regenerative medicine approach to reconstruction of the equine upper airway.

Airway obstruction is a common cause of poor performance in horses. Structural abnormalities (insufficient length, rigidity) can be a cause for the obstruction. Currently, there are a few effective clinical options for reconstruction of the equine larynx. A regenerative medicine approach to reconstruction may provide the capability to stabilize laryngeal structures and to encourage restoration of site-appropriate, functional, and host-derived tissue. The purpose of this study was the histopathological evaluation of (1) decellularization of equine (horse) laryngeal cartilages (epiglottis and arytenoids); (2) the host response to decellularized laryngeal cartilages implanted subcutaneously in a donkey model as a test of biocompatibility; and (3) the use of decellularized laryngeal cartilages in a clinically relevant pilot study in the horse larynx. Equine laryngeal cartilages were found to be sufficiently decellularized and were subsequently implanted subcutaneously in donkeys to test biocompatibility. After 4 weeks, the implanted cartilage was harvested. In the subcutaneous model, the samples did not elicit a rejection or foreign body type reaction and were judged suitable for implantation in a clinically relevant equine model. Implants were placed in the upper airway (arytenoids and epiglottis) of one horse. At 4 weeks, the implants were observed to remodel rapidly and were replaced by dense connective tissue with signs of new hyaline cartilage formation in the arytenoids and by connective tissue containing glandular structures and an epithelial covering in the epiglottis. The results of the present study demonstrate the feasibility of a scaffold-based regenerative medicine approach to reconstruction of the equine upper airway; however, further studies investigating long-term integration, formation of new cartilage, and mechanical properties are needed.

Muscular anatomy of the human ventricular folds.

OBJECTIVES: Our purpose in this study was to better understand the muscular anatomy of the ventricular folds in order to help improve biomechanical modeling of phonation and to better understand the role of these muscles during phonatory and nonphonatory tasks. METHODS: Four human larynges were decalcified, sectioned coronally from posterior to anterior by a CryoJane tape transfer system, and stained with Masson's trichrome. The total and relative areas of muscles observed in each section were calculated and used for characterizing the muscle distribution within the ventricular folds. RESULTS: The ventricular folds contained anteriorly coursing thyroarytenoid and ventricularis muscle fibers that were in the lower half of the ventricular fold posteriorly, and some ventricularis muscle was evident in the upper and lateral portions of the fold more anteriorly. Very little muscle tissue was observed in the medial half of the fold, and the anterior half of the ventricular fold was largely devoid of any muscle tissue. All 4 larynges contained muscle bundles that coursed superiorly and medially through the upper half of the fold, toward the lateral margin of the epiglottis. CONCLUSIONS: Although variability of expression was evident, a well-defined thyroarytenoid muscle was readily apparent lateral to the arytenoid cartilage in all specimens.

An investigation of articulatory setting using real-time magnetic resonance imaging.

This paper presents an automatic procedure to analyze articulatory setting in speech production using real-time magnetic resonance imaging of the moving human vocal tract. The procedure extracts frames corresponding to inter-speech pauses, speech-ready intervals and absolute rest intervals from magnetic resonance imaging sequences of read and spontaneous speech elicited from five healthy speakers of American English and uses automatically extracted image features to quantify vocal tract posture during these intervals. Statistical analyses show significant differences between vocal tract postures adopted during inter-speech pauses and those at absolute rest before speech; the latter also exhibits a greater variability in the adopted postures. In addition, the articulatory settings adopted during inter-speech pauses in read and spontaneous speech are distinct. The results suggest that adopted vocal tract postures differ on average during rest positions, ready positions and inter-speech pauses, and might, in that order, involve an increasing degree of active control by the cognitive speech planning mechanism.

[Numerical simulation on cycle change form of the pressure and wall shear in human upper respiratory tract].

The research on cycle change form of the pressure and the wall shear in human upper respiratory tract can strengthen understanding of the characteristics of the airflow in the place and provide us with a scientific basis for analyzing the diffusion, transition and deposition patterns of aerosol there. In our study, we used large eddy simulation to emulate the pressure and wall shear in human upper respiratory tract in conditions of the low intensive respiratory patterns, and discussed the distributing disciplinarian of the pressure and wall shear in mouth-throat model and trachea-triple bifurcation. The results showed that the pressure gradient variation in human upper respiratory tract was mainly fastened from root of epiglottis to trachea. The minimum pressure at the interim of inspiration was a duplication of the interim of expiration, and located on the posterior wall of the glottis. The pressure gradient variation was evident on trachea and its fork. The wall shear changed with the velocity of the air flow, and its direction changed periodically with breath cycle.