Intravelar and Extravelar Portions of Soft Palate Muscles in Velic Constrictions: A Three-Dimensional Modeling Study

Three-dimensional finite element analysis on stress distribution after different palatoplasty and levator veli palatini muscle reconstruction

OBJECTIVES

To establish a three-dimensional finite element model of the upper palate, pharyngeal cavity, and levator veli palatini muscle in patients with unilateral complete cleft palate, simulate two surgical procedures that the two-flap method and Furlow reverse double Z method, observe the stress distribution of the upper palate soft tissue and changes in pharyngeal cavity area after different surgical methods, and verify the accuracy of the model by reconstructing and measuring the levator veli palatini muscle.

MATERIALS AND METHODS

Mimics, Geomagic, Ansys, and Hypermesh were applied to establish three-dimensional finite element models of the pharyngeal cavity, upper palate, and levator veli palatini muscle in patients with unilateral complete cleft palate. The parameters including length, angle, and cross-sectional area of the levator veli palatini muscle etc. were measured in Mimics, and two surgical procedures that two-flap method and Furlow reverse double Z method were simulated in Ansys, and the area of pharyngeal cavity was measured by hypermesh.

RESULTS

A three-dimensional finite element model of the upper palate, pharyngeal cavity, and bilateral levator veli palatini muscle was established in patients with unilateral complete cleft palate ; The concept of horizontal projection characteristics of the palatal dome was applied to the finite element simulation of cleft palate surgery, vividly simulating the displacement and elastic stretching of the two flap method and Furlow reverse double Z method during the surgical process; The areas with the highest stress in the two-flap method and Furlow reverse double Z method both occur in the hard soft palate junction area; In resting state, as measured, the two flap method can narrow the pharyngeal cavity area by 50.9%, while the Furlow reverse double Z method can narrow the pharyngeal cavity area by 65.4%; The measurement results of the levator veli palatini muscle showed no significant difference compared to previous studies, confirming the accuracy of the model.

CONCLUSIONS

The finite element method was used to establish a model to simulate the surgical procedure, which is effective and reliable. The area with the highest postoperative stress for both methods is the hard soft palate junction area, and the stress of the Furlow reverse double Z method is lower than that of the two-flap method. The anatomical conditions of pharyngeal cavity of Furlow reverse double Z method are better than that of two-flap method in the resting state.

CLINICAL RELEVANCE

This article uses three-dimensional finite element method to simulate the commonly used two-flap method and Furlow reverse double Z method in clinical cleft palate surgery, and analyzes the stress distribution characteristics and changes in pharyngeal cavity area of the two surgical methods, in order to provide a theoretical basis for the surgeon to choose the surgical method and reduce the occurrence of complications.

Three-dimensional Anatomy of the Velopharyngeal Muscles in the Cleft Palate

OBJECTIVE

We have used micro-computed tomography (CT) to elucidate the relationship between the muscle fibers in specimens with cleft palate. These findings could be useful for muscle reconstruction in cleft palate repair and to better understand cleft palate speech.

DESIGN

Cadaveric anatomical study.

PARTICIPANTS

This study included three specimens with cleft palate.

INTERVENTION

The specimens were stained with phosphomolybdic acid and scanned by Micro-CT.

MAIN OUTCOME MEASURE(S)

The anatomy of the muscles.

RESULTS

Using 2D projection images and 3D reconstruction models, subtle anatomical structures could be observed in the muscles. The attachment of the levator veli palatini (LVP) was not at the posterior edge of the hard palate or palatine aponeurosis (PA), but at the anterior 21.71-44.2% of the cleft edge. The palatopharyngeal (PP) was composed of two bundles: inferior and superior heads, which clasped the LVP. The uvularis was unevenly distributed, and located on both sides of the cleft edge, originating at the edge. The palatoglossus, superior constrictor of pharynx and anatomical structure around the pterygoid hamulus, were normal. The PA, PP and LVP were attached to the cleft edge from front to back, in that order. The position of the uvularis was not fixed.

CONCLUSIONS

With the help of Micro-CT technology, detailed anatomical features and the relationship between muscles could be visualized. In the specimen with cleft palate, muscles in the soft palate were associated with the pharyngeal muscles, which formed the 3D "velopharyngeal muscles complex." These findings provide anatomical evidence for muscle reconstruction in cleft palate repair.

Robustness of lateral tongue bracing under bite block perturbation

Lateral tongue bracing is a lingual posture in which the sides of the tongue are held against the palate and upper molars, and has been observed cross-linguistically. However, it is unknown whether lateral bracing makes adjustments to external perturbation like other body postures. The present study aims to test the robustness of lateral tongue bracing with three experiments. The first baseline experiment was an analysis of an electropalatogram database and the results showed lateral bracing being continuously maintained. The second experiment applied an external perturbation during speech production. A bite block was held between participants' teeth while intra-oral video was used to record contact between the sides of the tongue and upper molars during speech. The results indicated that lateral bracing was maintained most of the time during speech. The third experiment included simulations investigating the activation of tongue muscles relevant to lateral bracing at different degrees of jaw opening. The results show that bracing requires higher activation of bracing agonists and lower activation of bracing antagonists as jaw opening increases. Our results suggest that lateral tongue bracing is actively maintained and robust under external perturbation and further indicate it serves as an essential lingual posture during speech production.

Vowel height and velum position in German: Insights from a real-time magnetic resonance imaging study

Velum position was analysed as a function of vowel height in German tense and lax vowels preceding a nasal or oral consonant. Findings from previous research suggest an interdependence between vowel height and the degree of velum lowering, with a higher velum during high vowels and a more lowered velum during low vowels. In the current study, data were presented from 33 native speakers of Standard German who were measured via non-invasive high quality real-time magnetic resonance imaging. The focus was on exploring the spatiotemporal extent of velum lowering in tense and lax /a, i, o, ø/, which was done by analysing velum movement trajectories over the course of VN and VC sequences in CVNV and CVCV sequences by means of functional principal component analysis. Analyses focused on the impact of the vowel category and vowel tenseness. Data indicated that not only the position of the velum was affected by these factors but also the timing of velum closure. Moreover, it is argued that the effect of vowel height was to be better interpreted in terms of the physiological constriction location of vowels, i.e., the specific tongue position rather than phonetic vowel height.

Obstructive Sleep Apnea and Role of the Diaphragm

Obstructive sleep apnea (OSA) causes multiple local and systemic pathophysiological consequences, which lead to an increase in morbidity and mortality in patients suffering from this disorder. OSA presents with various nocturnal events of apnoeas or hypopneas and with sub-clinical airflow limitations during wakefulness. OSA involves a large percentage of the population, particularly men, but the estimate of OSA patients could be much broader than data from the literature. Most of the research carried out in the muscle field is to understand the causes of the presence of chronic nocturnal desaturation and focus on the genioglossus muscle and other muscles related to dilating the upper airways. Sparse research has been published regarding the diaphragm muscle, which is the main muscle structure to insufflate air into the airways. The article reviews the functional anatomy of the muscles used to open the upper respiratory tract and the non-physiological adaptation that follows in the presence of OSA, as well as the functional anatomy and pathological adaptive aspects of the diaphragm muscle. The intent of the text is to highlight the disparity of clinical interest between the dilator muscles and the diaphragm, trying to stimulate a broader approach to patient evaluation.

Three-Dimensional Anatomy of the Palatopharyngeus and Its Relation to the Levator Veli Palatini Based on Micro-Computed Tomography

BACKGROUND

Although multiple studies have been reported on the palatopharyngeus and levator veli palatini, their subtle anatomy and functions remain unclear. The authors elucidated the relationship between these muscles and their functional implications based on three-dimensional digital techniques.

METHODS

Cadaveric specimens were stained with iodine-potassium iodide and scanned using micro-computed tomography. The muscle fibers were drawn on the exported Imaging and Communications in Medicine images to reconstruct a three-dimensional model and further simplified.

RESULTS

In the soft palate, the palatopharyngeus was divided into three bundles. The largest inferior head was found to attach to the palatine aponeurosis, soft palate, and the hard palate on the oral side, which occupied approximately the anterior 28.4 to 36.2 percent of the soft palate in the midline. The superior head was thin and attached to the palatine aponeurosis and the surrounding mucosa on the nasal side. The posterior head was located posterior to the levator veli palatini with fibers attaching to the levator veli palatini and the median portion of the uvula. The levator veli palatini was clasped by the three heads of the palatopharyngeus. The fasciculi of the palatopharyngeus converged into a bundle of muscles at the pharynx and inserted into the lateral and posterior pharyngeal wall.

CONCLUSIONS

The palatopharyngeus is the largest muscle that connects the soft palate and pharyngeal wall; it closely coordinates with the levator veli palatini to control levator veli palatini overlifting, narrow the velopharyngeal port with the help of the superior constrictor, and elevate the pharynx. The palatopharyngeus and levator veli palatini help each other in velopharyngeal closure through coordination from other muscles.

Velopharyngeal Muscle Morphology in Children With Unrepaired Submucous Cleft Palate: An Imaging Study

OBJECTIVE

To identify quantitative and qualitative differences in the velopharyngeal musculature and surrounding structures between children with submucous cleft palate (SMCP) and velopharyngeal insufficiency (VPI) and noncleft controls with normal anatomy and normal speech.

METHODS

Magnetic resonance imaging was used to evaluate the velopharyngeal mechanism in 20 children between 4 and 9 years of age; 5 with unrepaired SMCP and VPI. Quantitative and qualitative measures of the velum and levator veli palatini in participants with symptomatic SMCP were compared to noncleft controls with normal velopharyngeal anatomy and normal speech.

RESULTS

Analysis of covariance revealed that children with symptomatic SMCP demonstrated increased velar genu angle (15.6°, P = .004), decreased α angle (13.2°, P = .37), and longer (5.1 mm, P = .32) and thinner (4 mm, P = .005) levator veli palatini muscles compared to noncleft controls. Qualitative comparisons revealed discontinuity of the levator muscle through the velar midline and absence of a musculus uvulae in children with symptomatic SMCP compared to noncleft controls.

CONCLUSIONS

The levator veli palatini muscle is longer, thinner, and discontinuous through the velar midline, and the musculus uvulae is absent in children with SMCP and VPI compared to noncleft controls. The overall velar configuration in children with SMCP and VPI is disadvantageous for achieving adequate velopharyngeal closure necessary for nonnasal speech compared to noncleft controls. These findings add to the body of literature documenting levator muscle, musculus uvulae, and velar and craniometric parameters in children with SMCP.

Quantal biomechanical effects in speech postures of the lips

The unique biomechanical and functional constraints on human speech make it a promising area for research investigating modular control of movement. The present article illustrates how a modular control approach to speech can provide insights relevant to understanding both motor control and observed variation across languages. We specifically explore the robust typological finding that languages produce different degrees of labial constriction using distinct muscle groupings and concomitantly distinct lip postures. Research has suggested that these lip postures exploit biomechanical regions of nonlinearity between neural activation and movement, also known as quantal regions, to allow movement goals to be realized despite variable activation signals. We present two sets of computer simulations showing that these labial postures can be generated under the assumption of modular control and that the corresponding modules are biomechanically robust: first to variation in the activation levels of participating muscles, and second to interference from surrounding muscles. These results provide support for the hypothesis that biomechanical robustness is an important factor in selecting the muscle groupings used for speech movements and provide insight into the neurological control of speech movements and how biomechanical and functional constraints govern the emergence of speech motor modules. We anticipate that future experimental work guided by biomechanical simulation results will provide new insights into the neural organization of speech movements.NEW & NOTEWORTHY This article provides additional evidence that speech motor control is organized in a modular fashion and that biomechanics constrain the kinds of motor modules that may emerge. It also suggests that speech can be a fruitful domain for the study of modularity and that a better understanding of speech motor modules will be useful for speech research. Finally, it suggests that biomechanical modeling can serve as a useful complement to experimental work when studying modularity.

Identifying Predictors of Levator Veli Palatini Muscle Contraction During Speech Using Dynamic Magnetic Resonance Imaging

Purpose The purpose of this study was to identify predictors of levator veli palatini (LVP) muscle shortening and maximum contraction velocity in adults with normal anatomy. Method Twenty-two Caucasian English-speaking adults with normal speech and resonance were recruited. Participants included 11 men and 11 women (M = 22.8 years, SD = 4.1) with normal anatomy. Static magnetic resonance images were obtained using a three-dimensional static imaging protocol. Midsagittal and oblique coronal planes were established for visualization of the velum and LVP muscle at rest. Dynamic magnetic resonance images were obtained in the oblique coronal plane during production of "ansa." Amira 6.0.1 Visualization and Volume Modeling Software and MATLAB were used to analyze images and calculate LVP shortening and maximum contraction velocity. Results Significant predictors (p < .05) of maximum LVP shortening during velopharyngeal closure included mean extravelar length, LVP origin-to-origin distance, velar thickness, pharyngeal depth, and velopharyngeal ratio. Significant predictors (p < .05) of maximum contraction velocity during velopharyngeal closure included mean extravelar length, intravelar length, LVP origin-to-origin distance, and velar thickness. Conclusions This study identified six velopharyngeal variables that predict LVP muscle function during real-time speech. These predictors should be considered among children and individuals with repaired cleft palate in future studies.