Submucosal Elastic Laminae of the Middle and Lower Pharynx: A Histological Study Using Elderly Cadaveric Specimens.

Although the pharyngeal wall is well known to have high elasticity, the distribution of submucosal elastic fibers has not been described. Observations of histological sections of the mid and lower pharyngeal walls from 15 elderly donated cadavers were made. We found two distinct submucosal tissue layers with a high content of elastic fibers (tentatively termed the "submucosal elastic laminae"). The inferolateral elastic lamina was restricted to the level from the upper part of the arytenoid to the lower end of the inferior cornu of the thyroid cartilage. It originated from the pharyngeal submucosa, extended laterally along the inner aspect of the thyropharyngeal muscle, and inserted into the posterior margin of the thyroid cartilage including the cornu. The posteromedial lamina extended along the supero-inferior axis from a level above the greater horn of the hyoid bone to reach the muscularis mucosae of the cervical esophagus. The inferolateral and posteromedial laminae were connected at levels below the cricoarytenoid joint. Individual variations were evident in their thicknesses (ranging from almost absent to 0.3 mm) as well as the extent of connection between them. In association with striated muscle function, the inferolateral lamina seemed to suspend the lower pharyngeal mucosa, while the posteromedial lamina seemed to provide mucosal fold forcing smoothly peristaltic conveyance of a bolus during swallowing.

Membranous and cartilaginous vocal fold adduction in singing.

While vocal fold adduction is an important parameter in speech, relatively little has been known on the adjustment of the vocal fold adduction in singing. This study investigates the possibility of separate adjustments of cartilaginous and membranous vocal fold adduction in singing. Six female and seven male subjects, singers and non-singers, were asked to imitate an instructor in producing four phonation types: "aBducted falsetto" (FaB), "aDducted falsetto" (FaD), "aBducted Chest" (CaB), and "aDducted Chest" (CaD). The phonations were evaluated using videostroboscopy, videokymography (VKG), electroglottography (EGG), and audio recordings. All the subjects showed less posterior (cartilaginous) vocal fold adduction in phonation types FaB and CaB than in FaD and CaD, and less membranous vocal fold adduction (smaller closed quotient) in FaB and FaD than in CaB and CaD. The findings indicate that the exercises enabled the singers to separately manipulate (a) cartilaginous adduction and (b) membranous medialization of the glottis though vocal fold bulging. Membranous adduction (monitored via videokymographic closed quotient) was influenced by both membranous medialization and cartilaginous adduction. Individual control over these types of vocal fold adjustments allows singers to create different vocal timbres.

Laryngeal Reconstruction Using Tissue-Engineered Implants in Pigs: A Pilot Study.

OBJECTIVE/HYPOTHESIS: There are currently no treatments available that restore dynamic laryngeal function after hemilaryngectomy. We have shown that dynamic function can be restored post hemilaryngectomy in a rat model. Here, we report in a first of its kind, proof of concept study that this previously published technique is scalable to a porcine model. STUDY DESIGN: Animal study. METHODS: Muscle and fat biopsies were taken from three Yucatan minipigs. Muscle progenitor cells (MPCs) and adipose stem cells (ASCs) were isolated and cultured for 3 weeks. The minipigs underwent a left laterovertical partial laryngectomy sparing the left arytenoid cartilage and transecting the recurrent laryngeal nerve. Each layer was replaced with a tissue-engineered implant: 1) an acellular mucosal layer composed of densified Type I oligomeric collagen, 2) a skeletal muscle layer composed of autologous MPCs and aligned oligomeric collagen differentiated and induced to express motor endplates (MEE), and 3) a cartilage layer composed of autologous ASCs and densified oligomeric collagen differentiated to cartilage. Healing was monitored at 2 and 4 weeks post-op, and at the 8 week study endpoint. RESULTS: Animals demonstrated appropriate weight gain, no aspiration events, and audible phonation. Video laryngoscopy showed progressive healing with vascularization and re-epithelialization present at 4 weeks. On histology, there was no immune reaction to the implants and there was complete integration into host tissue with nerve and vascular ingrowth. CONCLUSIONS: This pilot study represents a first in which a transmural vertical partial laryngectomy was performed and successfully repaired with a customized, autologous stem cell-derived multi-layered tissue-engineered implant. LEVEL OF EVIDENCE: NA Laryngoscope, 131:2277-2284, 2021.

A muscle controlled finite-element model of laryngeal abduction and adduction.

A three-dimensional finite-element model was developed to simulate the complex movement of the laryngeal cartilages during vocal fold abduction and adduction. The model consists of cricoid and arytenoid cartilages, as well as the intralaryngeal muscles and vocal folds. The active and passive properties of the muscles were idealised by one-dimensional elements based on the Hill theory. Its controlling input value is a time dependent stimulation rate. Optimisation loops have been carried out for the arrangement of the individual stimulation rates. Since in vivo measurements are not feasible, the developed biomechanical model shall be used to analyse the force distribution within the laryngeal muscles during phonatory manoeuvres. Simulations of abduction and adduction in different pitches of voice lead to realistic tensions of the vocal folds. The model is a first step to analyse motional vocal fold diseases and to predict the consequences of phonosurgical interventions.

[The tensegrity concept applied to the laryngeal biodynamics]. / Du concept de tenségrité à la biodynamique laryngée.

The knowledge of spaces and sliding ways of the forehead part of the neck must be accomplished, however the microscopic observation of these sliding ways shows in fact a real concrete material continuity, through the existence of a binding tissue between the sliding structures. This tissue is shaped in a web form system of multimicrovacuolar collagenic fibers. It respects the functional unit, while saving the relative independance of moving between the different structures concerned. The architectural features of any living tissue may be reported to a tensegrity system. The word of tensegrity is a portmanteau of tensional-integrity, as proposed by the american architect Richard Buckmister Fuller. Following tensegrity the laryngeal biodynamic behaviour is based on two sets of tensions and compressions applied on itself. The laryngeal system is therefore in a constant balance of tissular tensions. The multimicrovacuolar system has a main place. This new point of view may be applied to the laryngeal dysfunctions.

Morphology of laryngeal cartilage of the nine-banded armadillo (Dasypus novemcinctus) Linnaeus, 1758.

Armadillos, Xenarthras representatives, known for adaptability to different ecosystems, own specific morphophysiological characteristics that are not known and deserve to be studied. The aim of this study was to describe the morphology of cartilage of the larynx of the nine-banded armadillo (Dasypus novemcinctus). Five dead armadillos were donated by the Chico Mendes Institute of Biodiversity (ICMBio-PI) to the Federal University of Piauí. The animals were fixed and dissected for removal of the larynx. The cartilages were identified and described, photodocumented, and schematized. Fragments with about 0.5 cm of each cartilage were collected and submitted to classical histology for Hematoxylin-Eosin coloring. The slides were assembled in enterlan and analyzed under a light microscope. The larynx of the armadillo (D. novemcinctus) is located in the mentonian region, ventral to the esophagus, and due to the total positioning of the tongue in the oral cavity, there is also a cranial cervical position in this species. The larynx has five cartilages, they are: a cricoid, a thyroid, an epiglottis, and two arytenoids. The corniculate process is present; however, the cuneiform process is absent. The epiglottis has a discrete bifurcation at its apex. In all cartilages epithelial variations are observed. The tissues are varied from squamoso stratified to cylindrical pseudostratified, with propria lamina rich in mucoserosas glands. With the exception of epiglottic cartilage, predominantly elastic, the rest are hyaline. The larynx of D. novemcinctus, although the same number of cartilages, differs morphologically and microscopically from the larynx of other species.

3D analysis of the movements of the laryngeal cartilages during singing.

OBJECTIVE: The vocal range of untrained singers rarely exceeds one and a half octaves, but professional singers have a range of at least two and a half octaves. The aim of this study was to better understand the muscle and cartilage movements responsible for the control of vocal pitch in singing. STUDY DESIGN: Prospective study. METHODS: We recruited 49 female professional singers (25 sopranos and 24 altos) and analyzed laryngeal three-dimensional images derived from high-resolution computed tomography scans obtained at the mean speaking fundamental frequency (F0) and at one (F1) and two octaves (F2) above this pitch. RESULTS: From F0 to F1, the only observable movement was a backward cricoid tilting caused by the cricothyroid muscles (CTMs), leading to vocal fold stretching. Above F1, a medial rotation and inward rocking of the arytenoid cartilages was observed, caused by the lateral cricothyroid muscles (LCAMs) and leading to inferior displacement of the vocal process of the arytenoid cartilage, and thus to further vocal fold stretching. CONCLUSION: Trained singers achieve the first octave of pitch elevation by simple cricothyroid approximation. Further pitch elevation necessitates a complex movement of the arytenoids, first by CTM contraction and second by LCAM contraction. LEVEL OF EVIDENCE: 4. Laryngoscope, 127:1639-1643, 2017.

Three-dimensional Imaging of High-resolution Computer Tomography of Singers' Larynges-A Pilot Study.

OBJECTIVES/HYPOTHESIS: Biplanar imaging technique is not sufficient for an exact visualization and evaluation of the laryngeal biomechanics during speaking or singing. The aim of this pilot study was to test a 3D-visualization software MIMICS (Materialize Interactive Medical Image Control System, Materialize, Leuven, Belgium) for visualizing laryngeal cartilages and resonance space of living humans during singing based on high-resolution computed tomography (HRCT) and analyzing the biomechanics thereof. STUDY DESIGN: This is a prospective pilot study. METHODS: A total of 10 professional female singers (five sopranos and five altos) was scanned with HRCT in three singing positions fundamental frequency (ƒo), first octave (ƒo+1 8va) and second octave (ƒo+2 8va). RESULTS: All relevant laryngeal structures and resonance space could be 3D visualized. Superimposing the different HRCT scans showed an inward rotation and rocking of the arytenoid cartilages from ƒo+1 8va to ƒo+2 8va and a backward tilting of the cricoid cartilage from ƒo+1 8va to ƒo+2 8va. Moreover, we could demonstrate a vocal fold elongation of 13% from ƒo to ƒo+1 8va and an additional elongation from ƒo+1 8va to ƒo+2 8va of 10% in type A cricothyroid joints (CTJ) A and 4% in CTJ's type B/C. There were no significant differences between sopranos and altos in all parameters (length of the glottis, subglottic diameter, distance between anterior commissure and cervical spine, and CTJ distribution). CONCLUSIONS: This noninvasive 3D-visualization technique with MIMICS allows the anatomical structures and landmarks of the larynx to be analyzed. We believe that this pilot study will serve as a basis for further biomechanical studies on speakers' and singers' larynges.

On Short-Time Estimation of Vocal Tract Length from Formant Frequencies.

Vocal tract length is highly variable across speakers and determines many aspects of the acoustic speech signal, making it an essential parameter to consider for explaining behavioral variability. A method for accurate estimation of vocal tract length from formant frequencies would afford normalization of interspeaker variability and facilitate acoustic comparisons across speakers. A framework for considering estimation methods is developed from the basic principles of vocal tract acoustics, and an estimation method is proposed that follows naturally from this framework. The proposed method is evaluated using acoustic characteristics of simulated vocal tracts ranging from 14 to 19 cm in length, as well as real-time magnetic resonance imaging data with synchronous audio from five speakers whose vocal tracts range from 14.5 to 18.0 cm in length. Evaluations show improvements in accuracy over previously proposed methods, with 0.631 and 1.277 cm root mean square error on simulated and human speech data, respectively. Empirical results show that the effectiveness of the proposed method is based on emphasizing higher formant frequencies, which seem less affected by speech articulation. Theoretical predictions of formant sensitivity reinforce this empirical finding. Moreover, theoretical insights are explained regarding the reason for differences in formant sensitivity.

Functional anatomy and physiology of the upper esophageal sphincter.

Upper esophageal sphincter (UES) refers to the high-pressure zone located in between the pharynx and the cervical esophagus. The physiological role of this sphincter is to protect against reflux of food into the airways as well as prevent entry of air into the digestive tract. UES is a musculocartilaginous structure with its anterior wall being formed by the full extent of the posterior surface of the cricoid cartilage and arytenoid and interarytenoid muscles in the upper part. Posteriorly and laterally the cricopharyngeus (CP) muscle is a definitive component of the UES. CP has many unique characteristics: it is tonically active, has a high degree of elasticity, does not develop maximal tension at basal length, and is composed of a mixture of slow- and fast-twitch fibers, with the former predominating. These features enable the cricopharyngeus to maintain a resting tone and yet be able to stretch open by distracting forces, such as a swallowed bolus and hyoid and laryngeal excursion. CP, however, constitutes only the lower one third of the entire high-pressure zone. The thyropharyngeus (TP) muscle accounts for the remaining upper two thirds of the UES. The UES pressure is not entirely the result of myogenic activity, as a component of the pressure is the result of passive elasticity of the tissues. The opening of the UES involves relaxation of CP and TP muscles and forward movement of the larynx by the contraction of hyoid muscles. The UES function is controlled by a variety of reflexes that involve afferent inputs to the motorneurons innervating the sphincter. These physiological reflexes elicit either contraction or opening of the UES. Inability of the sphincter to open leads to difficulty in swallowing. Opening of the sphincter without associated CP relaxation leads to the clinical syndrome of cricopharyngeal bar.

Arytenoid vocal shunt in laryngectomized patients.

A method is presented for forming short, mucosa-lined vocal shunt in cases of supracricoid laryngectomy with preservation of one or two arytenoids, or the interarytenoid fold alone. On the basis of radiologic and particularly radiocinematographic examinationion of the anterior pharyngeal wall is of paramount importance. In cases of complete absence of leakage, said wall lies in the plane of the arytenoids or somewhat posteriorly. After simple supracricoid laryngectomy it is possible to prevent aspiration also by translocation of the anterior pharyngeal wall into the plane of the cricoid cartilage plate. The clinical experience with this supracricoid shunt is still scanty. Of 25 cases with the arytenoid vocal shunt, phonation was possible in 22 cases under the expiratory pressure of 20-45 cm H2O; in one under the more elevated pressure, and in the last two the result is still not known. Loudness of speech was 70-100 db and its comprehensibility 73-90 percent. Complete absence of leakage was observed in 17 cases, "practical" prevention of aspiration (some drops of thin fluids, no saliva) in seven cases, profuse leakage in one case (ceased after correction), In the last 10 consecutive cases the problem of aspiration was completely eliminated. Advantages and disadvantages of our own method in comparison with Asai's method have been presented.

The anatomy and movements of the cricoarytenoid joint.

The cricoarytenoid joints of 45 larynges were dissected and examined with respect to ligaments, articulating surfaces and movements. In this study the capsule of the joint was uniformly thin, and was strengthened by a superficial, medially placed, flattened band of fibers of one or two strata, known as the posterior cricoarytenoid ligament. Three movements of the arytenoid cartilage at this joint were found, the axes and ranges of which were directly related to the shape and position of the cricoid facet. Notwithstanding these differences, the positions of all the vocal folds in extreme adduction or abduction were similar. These findings contradict the traditional concepts of uniformity of the anatomy and movements of the cricoarytenoid joint and also the position and therefore name, of the "posterior" cricoarytenoid ligament.

Biomechanical characteristics of the human trachea.

Previous experiments using mercury-in-Silastic strain gauges in dogs revealed the trachea to be a dynamic organ. The cartilaginous rings and intercartilaginous membranes are unique in adapting to the physiologic demands of respiration, deglutition, and gravity. Alterations in tracheal biomechanics following segmental tracheal resection were also documented. In the present study, a new device was used to measure the stress-strain characteristics of the human trachea. The machine can be used to measure tension across trachea rings or the entire trachea. The results of these experiments indicate that the human trachea is a complex biomechanical organ and that it responds distinctively to stress.

Geometric characterization of the laryngeal cartilage framework for the purpose of biomechanical modeling.

Some new anatomic data on the laryngeal cartilage framework have been obtained for the biomechanical modeling of the larynx. This study attempted to define and measure some biomechanically important morphometric features of the laryngeal framework, including both the human and the canine laryngeal frameworks, because the canine larynx has been frequently used as an animal model in gross morphology and in physiological experiments. The larynges of 9 men, 7 women, and 9 dogs were harvested and dissected after death. Linear and angular geometric measurements on the thyroid cartilage, the cricoid cartilage, and the arytenoid cartilage were made with a digital caliper and a protractor, respectively. The results are useful for constructing quantitative biomechanical models of vocal fold vibration and posturing (abduction and adduction), eg, continuum mechanical models and finite-element models of the vocal folds.

Transmucosal electrical stimulation of laryngeal muscles.

A new technique is described that enables discrete activation of individual laryngeal muscles by electrical stimulation across overlying mucosa. In 15 dogs, we defined six distinct motor points by transmucosal stimulation at 3 mA while observing the resulting characteristic position of the arytenoid and true vocal cord. Five dogs were then paralyzed with succinylcholine in order to simulate bilateral vocal cord paralysis. Application of a 3-mA stimulus at each motor point yielded no motion of the cords, but when the current was increased to 20 mA, characteristic responses were elicited. In five other dogs, botulinum toxin was injected directly into laryngeal muscles. Stimulation was used in an attempt to quantify the degree of neuromuscular blockade. In the last group of five dogs, we simulated cricoarytenoid arthritis by scarifying the joint. The extent and nature of the joint's impairment could be demonstrated by stimulation. Transmucosal stimulation appears promising as a clinical technique for correlating particular vocal cord movements and thresholds of activation with specific laryngeal disorders. Additionally, such a technique may be useful in clarifying how each laryngeal muscle acts upon the cricoarytenoid joint.

Effects of lateral manual compression upon glottic incompetence: objective evaluations.

Forceful manual compression of the thyroid and cricoid cartilages modifies the position, shape, and tension of the vocal folds. This is the basis of the four laryngeal manual compression tests, adjunctive examinations used as a means of preoperative assessment of patients for medialization laryngoplasty, ie, Isshiki thyroplasty types I and IV and arytenoid adduction. The laryngeal manual compression tests are simple to perform and noninvasive. Each of the four examinations yields valuable information on the effects on the voice of changes in vocal cord characteristics produced by manual compression. In this report, one of the four tests, lateral manual compression, is evaluated objectively with well-attested methods of videostroboscopic, aerodynamic, and acoustic analysis. The technique of performing lateral manual compression is described, and advantages and disadvantages are noted and compared in 10 patients. Preliminary findings in 4 patients in this group indicate that medialization laryngoplasty should be considered when test results are conclusive of effective glottic closure. Data derived in this preliminary study will be augmented as patients are added to the series.

Functional anatomy of the larynx.

The larynx serves three basic functions in humans. In order of functional priority they are protective, respiratory, and phonatory. This article discusses these three roles in terms of phylogeny, developmental anatomy, and neuromuscular reflex activity.

Functional anatomy of the larynx.

The larynx should be thought of as a sphincteric valve mechanism in the neck. It is composed of a relatively rigid skeleton and an inner lining, which passively is displayed as a series of elastic folds. These folds are anchored superiorly to the skull base and inferiorly to the trachea. Active folding and unfolding are accomplished by external and internal muscle activity to meet the various functional demands placed upon the larynx.

Ossification within the primate larynx.

Ossification of the laryngeal cartilages is a random occurrence possibly related to age and sex. A wide variety of primate larynges have been examined radiologically, by macroscopic section or after whole organ serial section with the aim of determining presence of ossification. The results of this investigation will be presented in an attempt to establish possible correlation between structure, function and degree of ossification within each specific larynx. This is a unique enquiry which may assist in the understanding of ossification within the human larynx.

Effects of age and prosthesis material on in vitro cartilage retention of laryngoplasty prostheses in horses.

Cartilage retention strengths of laryngoplasty prostheses were compared in larynges of 2-, 3-, and 4-year-old horses, using doubled polyester and expanded polytetrafluoroethylene prostheses. Bilateral laryngoplasties were performed on each of 15 (seven 2-year-old, two 3-year-old, and six 4-year-old) larynges, which were collected at an abbatoir. Prostheses were secured to a mechanical testing machine, and tension causing arytenoid cartilage abduction was applied, until total failure of the cartilage or prosthesis resulted. Tension caused cricoid cartilage failure in 1 specimen, and muscular process cartilage failure in the remainder. There was no significant effect of age, prosthetic material, or side of prosthesis placement on cartilage retention of the prostheses. Additionally, frequency of multiple load-displacement peaks, indicating partial muscular process failure, was not affected by age or prosthetic material variables.