[Comparative role of the muscles of the nasopharynx and the glottis in inspiration of so-called "closed glottis" rumination].
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Animals↗
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Posterior glottis. Morphological study in excised human larynges.
Two sets of investigations were conducted with excised human larynges. The glottis was closely observed and photographed from above and below in three conditions: neutral, adduction, and abduction. The structure surrounding the posterior glottis was histologically investigated in the same three conditions. The results are as follows. The structure surrounding the posterior glottis consists of three portions: the posterior wall of the glottis, the lateral wall of the posterior glottis, and the cartilaginous portion of the vocal fold. During vocal fold adduction, the posterior part of the larynx closes completely not at the glottis but at the supraglottis, resulting in formation of a conic space in the posterior glottis that can be viewed only from below. The posterior glottis accounts for approximately 35% to 45% of the entire glottic length and 50% to 65% of the entire glottic area. The mucosa of the posterior glottis has ciliated epithelium. The lamina propria consists of two layers. The posterior glottis can be regarded as a respiratory glottis.
Adult↗
Flow visualization and pressure distributions in a model of the glottis with a symmetric and oblique divergent angle of 10 degrees.
Modeling the human larynx can provide insights into the nature of the flow and pressures within the glottis. In this study, the intraglottal pressures and glottal jet flow were studied for a divergent glottis that was symmetric for one case and oblique for another. A Plexiglas model of the larynx (7.5 times life size) with interchangeable vocal folds was used. Each vocal fold had at least 11 pressure taps. The minimal glottal diameter was held constant at 0.04 cm. The glottis had an included divergent angle of 10 degrees. In one case the glottis was symmetric. In the other case, the glottis had an obliquity of 15 degrees. For each geometry, transglottal pressure drops of 3, 5, 10, and 15 cm H2O were used. Pressure distribution results, suggesting significantly different cross-channel pressures at glottal entry for the oblique case, replicate the data in another study by Scherer et al. [J. Acoust. Soc. Am. 109, 1616-1630 (2001b)]. Flow visualization using a LASER sheet and seeded airflow indicated separated flow inside the glottis. Separation points did not appear to change with flow for the symmetric glottis, but for the oblique glottis moved upstream on the divergent glottal wall as flow rate increased. The outgoing glottal jet was skewed off-axis for both the symmetric and oblique cases. The laser sheet showed asymmetric circulating regions in the downstream region. The length of the laminar core of the glottal jet was less than approximately 0.6 cm, and decreased in length as flow increased. The results suggest that the glottal obliquity studied here creates significantly different driving forces on the two sides of the glottis (especially at the entrance to the glottis), and that the skewed glottal jet characteristics need to be taken into consideration for modeling and aeroacoustic purposes.
Air Pressure↗
Glottis narrowing in lung disease.
We measured the separation of the vocal folds, the glottis chink, on inspiration and expiration during quiet breathing in 34 patients with varying degrees of airflow obstruction as measured by forced expired volume in one second, Width of the glottis chink was calculated from photographs of the vocal folds taken via a fiberoptic bronchoscope. To adjust the differences in photographic image size caused by variations in instrument position, we predicted the internal anteroposterior (A.P) diameter of the glottis in each patient. This was made possible by the observed high correlation (r = 0.79) between A.P diameter of the glottis and height demonstrated in a separate study in 49 adult cadavers. In patients with airflow obstruction, the glottis chink was narrowed during quiet breathing, particularly on expiration. Such differences in glottis width between patients could not be attributed to frequency of breathing or tidal volume. Indeed, during high frequency breathing (panting) at 1 to 3 Hz studied in 18 patients, further glottis narrowing was commonly observed in those with airflow obstruction. Furthermore, when 13 patients performed a maximal exhalation, in those with airflow obstruction, the glottis remained narrowed, whereas in patients with FEV1 greater than 80% predicted, the glottis opened to an inspiratory width.l These observations suggest that narrowing of the glottis potentially plays an important part in controlling airflow in patients with airway obstruction.
Adult↗
Neurochemical markers in the nervous plexus of the canine glottis.
The structure of the nervous network and the distribution of tyrosine hydroxylase (TH)- and various neuropeptide-containing nerves were immunohistochemically studied in the glottis of the dog. The nervous network in the glottis revealed apparent regional differences in morphology. The nervous network in the cartilaginous vocal fold of the posterior glottis consisted of nerve bundles running parallel to the edge of the vocal fold. Only a small number of nerve bundles were observed in the anterior glottis, specifically in membranous vocal fold. In the subepithelial layer of the posterior glottis, a moderate number of galanin (GAL)-immunoreactive nerve fibers were observed, while only a few fibers were present in the anterior glottis. Numerous vasoactive intestinal peptide (VIP)-, GAL-, methionine-enkephalin (ENK)- and TH-immunoreactive nerve fibers were observed within and around the laryngeal submucosal seromucous gland. Many TH- and neuropeptide Y (NPY)-immunoreactive fibers were arranged around the blood vessels. In the epithelia, free nerve endings with immunoreactivity for substance P (SP) and calcitonin gene-related peptide (CGRP) was observed. Furthermore, nerve cell bodies with SP-, VIP-, GAL-, ENK-, and NPY-immunoreactivity were observed in the deep region of the submucosal layer. The results from the present study suggest that there is autonomic regulation of the glottis. Regional structural differences in the nervous network of the glottis may reflect functional differences.
Animals↗
Unsteady flow through in-vitro models of the glottis.
The unsteady two-dimensional flow through fixed rigid in vitro models of the glottis is studied in some detail to validate a more accurate model based on the prediction of boundary-layer separation. The study is restricted to the flow phenomena occurring within the glottis and does not include effects of vocal-fold movement on the flow. Pressure measurements have been carried out for a transient flow through a rigid scale model of the glottis. The rigid model with a fixed geometry driven by an unsteady pressure is used in order to achieve a high accuracy in the specification of the geometry of the glottis. The experimental study is focused on flow phenomena as they might occur in the glottis, such as the asymmetry of the flow due to the Coanda effect and the transition to turbulent flow. It was found that both effects need a relatively long time to establish themselves and are therefore unlikely to occur during the production of normal voiced speech when the glottis closes completely during part of the oscillation cycle. It is shown that when the flow is still laminar and symmetric the prediction of the boundary-layer model and the measurement of the pressure drop from the throat of the glottis to the exit of the glottis agree within 40%. Results of the boundary-layer model are compared with a two-dimensional vortex-blob method for viscous flow. The difference between the results of the simpiflied boundary-layer model and the experimental results is explained by an additional pressure difference between the separation point and the far field within the jet downstream of the separation point. The influence of the movement of the vocal folds on our conclusions is still unclear.
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Narrowing of glottis opening in humans associated with experimentally induced bronchoconstriction.
An index of the separation of the vocal cords during tidal breathing was obtained in humans; the area of the glottis opening was assessed from photographs of the vocal cord taken on inspiration and expiration via a fiber-optic bronchoscope. The index of glottis width was calculated from the area by dividing it with, as reference, the anteroposterior diameter of the glottis, a relatively invariant measurement of the glottis during breathing. Both inspiratory and expiratory glottis width decreased after histamine had been inhaled (dose range 2.4-9.6 mg) or injected intravenously (dose of 4 micrograms/kg), being associated with a reduction in forced expired volume in 1.0 s. Histamine, which acts directly on smooth muscle or bronchial irritant receptors, is unlikely to have directly caused contraction of the striated laryngeal musculature or to have stimulated receptors above the vocal cords. The narrowing of the glottis opening observed in humans may represent a reflex narrowing of the glottis in association with a reduction of intrapulmonary airway caliber.
Adult↗
The effect of a mechanical glottis on peak expiratory flow rate and time to peak flow during a peak expiratory flow manoeuvre: a study in normal subjects and patients with motor neurone disease.
We have evaluated a mechanical glottis in healthy volunteers and in patients with bulbar motor neurone disease. In healthy volunteers, the mechanical glottis increased peak flow rate and decreased the time to peak flow during forced expiration, but cough produced even higher flow rates and shorter times to peak flow. In patients, the mechanical glottis increased peak flow rate and decreased the time to peak flow. The mechanical glottis also produced higher peak flow rates when compared to the cough manoeuvres, and the time to peak flow was also significantly shorter with the mechanical glottis. We have shown that the use of a mechanical glottis tends to convert the airflow profile of a peak expiratory flow manoeuvre into that of a cough in both healthy volunteers and patients with motor neurone disease. Its potential role as an aid to clearance of airway secretions in patients with impaired laryngeal function remains to be seen.
Adult↗
Neuromuscular control of the glottis in a primitive air-breathing fish, Amia calva.
The neuromuscular control of the glottis, a muscular sphincter that controls air flow to and from the swim bladder, was investigated using in vitro preparations from bowfin (Amia calva). Stimulation of the ramus intestinalis branch of the vagus nerve caused an increase in isometric tension of the glottal musculature, indicating active closure. The glottis could be actively opened only by direct stimulation of muscle bundles lying lateral to the glottis. In 19 of 24 preparations supramaximal nerve stimulation (20 Hz, 10 V) caused a two-phase increase in muscle tension. Immediately after the onset of stimulation there was a rapid increase in muscle tension. After the end of the train of stimuli, the tension decreased and then again increased briefly followed by a slow return to baseline lasting approximately 60 s. The addition of hyoscine reduced maximum tension of the response by 63 +/- 7% and abolished the second slower element of the response to vagal stimulation. The remaining faster response to nerve stimulation was abolished by tubocurarine. Applied acetylcholine or carbachol mimicked the slow response, causing a slow-onset sustained contraction that was abolished by hyoscine. Hence, the musculature showed physiological characteristics of both skeletal and smooth muscle. Histological examination of the glottis confirmed the physiological results: smooth muscle fibers were found lining the pneumatic duct and lumen of the glottis arranged in a circular fashion around the lateral margins of the glottis. Distinct skeletal muscle bundles were found lateral to the smooth muscle and also arranged in parallel with the glottal lumen, forming a skeletal muscle sphincter.(ABSTRACT TRUNCATED AT 250 WORDS)
Acetylcholine↗
The posterior glottis.
The posterior glottis is an area of the larynx previously referred to by the terms 'posterior commissure' and 'interarytenoid'; these are poorly defined and a new definition of this unique area of the larynx is provided. Within the text is a series of experiments performed on nearly 300 larynges. The posterior glottis was examined in relation to the following: the embryology, the epithelium, mathematical dimensions, gross anatomy, microanatomical structures, submucosal spaces and the spread of carcinoma related to this area. Various significant findings were made. There exists a pharyngoglottic duct which divides the embryonic larynx into anterior (membranous) and posterior (cartilaginous) parts. The epithelium of the posterior glottis in neonates and non-smokers is respiratory in nature and the notion of a laryngeal respiratory function is reinforced by a mathematical analysis of the cross sectional areas of the larynx during inspiration. The presence of a posterior cricoarytenoid ligament which stabilizes the arytenoid is confirmed. The spread of carcinoma to the posterior glottis from the different primary laryngeal and pyriform fossa sites shows differing modes of invasion but in particular a direct extension and connection with the subglottis. The most significant conclusion from these studies is that the posterior glottis is so intimately related to the subglottis that it must be considered as part of the subglottis. The acceptance of this fact, however, requires a new definition of the larynx from that given by the American Joint Committee on Cancer Staging and that of U.I.C.C. The posterior glottis considered as part of the subglottis requires a review of our present understanding of the structure and function of the larynx and in particular the spread of cancer posteriorly.
Adult↗
[Anatomy of the glottis and subglottis in the pediatric larynx].
BACKGROUND: The morphological development of the human larynx during the first years of life has previously not been studied in detail and has mainly been described on a qualitative basis. This study seeks to provide detailed morphometric data on the regular anatomy of the vocal cords, the subglottic airway and the tracheal airway dimensions gained from plastinated whole organ serial sections of 43 infant larynges and to determine morphological changes with age. Such information may be useful for the understanding of pediatric airway disease or for laryngeal surgery in children. MATERIAL AND METHODS: The larynges of 43 children aged 1 to 60 months were plastinated. Whole organ serial sections were obtained by cutting the resulting specimen with a diamond band saw. Morphometry of whole-organ sections was accomplished using a high resolution, computer-based image analyzer. The total length of the glottis, length of the cartilaginous and ligamentous glottis, subglottic cartilaginous cross-section, subglottic airway and tracheal airway were determined for each specimen. RESULTS: The subglottic airway increases considerably in size during the first 2 years of life (from 13 to 28 mm2 in the means). Further growth seems to follow a linear mode. The relative proportion of the mucosal lining of the subglottic airway decreases likewise. While it occupies approximately 50% of the subglottic cartilaginous cross-section during the first two years of age, its relative proportion decreases to some 30 to 40% between age three to five. Other than in adults, and comparable to most mammals, the cartilaginous glottis accounts for 60 to 75% of the vocal folds' length in children under two years of age. The anterior ligamentous part of the glottis outsizes its posterior cartilaginous portion during the third year of life. CONCLUSION: This study supplies detailed morphometric data on the growth and structure of the human larynx during the first years of life that have not been available to date. Previous studies on the anatomical configuration of the infant larynx have focused on the the perinatal larynx, the prepuberal and puberal larynx, and the development of collagen fibres in the developing larynx. The human larynx has undergone significant evolutionary adaptations. Among them are the descent of the larynx, the capability of vocal fold adjustment in length, tension and shape, and the prominent configuration of the membranous part of the vocal folds as opposed to the cartilaginous part. The infant larynx is not just a miniature of the adult organ. It shows differences in its position relative to the vertebrate column, in the composition of cartilages and soft tissues, and in environmental adaptation. The present study is the first to supply detailed morphometric data on the growth and structure of the human larynx during the first five years of life and on the morphological changes of the larynx during this period. From these data it seems that some of the adaption of the human larynx as opposed to other vertebrates are not fully developed at birth, but undergo postnatal maturation. The relative proportions of the cartilaginous and membranous parts of the vocal folds clearly demonstrate this maturation process: While the posterior "respiratory" glottis accounts for some sixty to 75% of the total glottic length in newborns, its relative proportion decreases throughout the first years of life and finally equals the proportions of the adult larynx. Other than in adults, and in accordance with the literature, no sexual dimorphism of the larynx could be detected in this series of infant larynges. Morphometric data on the growth and structure of the human vocal folds and the subglottic airway during childhood are presented. Plastinated whole organ serial sections were used in the study to show the infant laryngeal morphology. The study provides quantitative anatomical data of clinical interest that light up the anatomy of the pediatric airways.
Adult↗
Evaluation of the lung function test in reversible glottis-dilating operations.
Our aim was to obtain an objective evaluation of the airway before and after reversible glottis-dilating operations using the lung function test. Bilateral abductor vocal cord paralysis remains mostly a complication of thyroid surgery. After thyroid surgery, the paralysis is potentially reversible, and the patient has a chance for recovery mostly in the first 6 months. According to these considerations, a reversible vocal cord laterofixation procedure was used instead of tracheostomy. The operations were performed endoscopically using high-frequency JET ventilation and the special endo-extralaryngeal suture technique by Lichtenberger. This technique was used in 92 cases. The pre- and postoperative data of reversible glottis-dilating techniques could be compared in 23 non-selected patients. Lung function tests that were performed were forced inspiratory volume (FIV1), forced expiratory volume (FEV1), peak inspiratory flow rate (PIF), peak expiratory flow rate (PEF) and resistance of the airways (Raw). For the evaluation of the functional results, we used the body-pletysmograph. Our aim was to obtain a quantitative evaluation of the results. These values allow us to compare the results achieved by using different glottis-dilating methods. The FEV1 (forced expiratory volume) improved 25%, and the FIV1 (forced inspiratory volume) improved 39% after the operations on average. PEF (peak expiratory flow rate) and PIF (peak inspiratory flow rate) improved 37 and 45% after glottis-dilating surgery on average. The Raw (resistence of airways) was 271.5% on average before the operations, and after reversible glottis-dilating operations decreased to a level of 200.6%.
Adolescent↗
Assessment of the results of glottis-dilating operations using lung function tests.
Our aim was to obtain an objective evaluation of the airway before and after glottis-dilating operations utilizing lung function tests. The charts of 109 patients who underwent either reversible or irreversible glottis-dilating operations by Lichtenberger were reviewed. 64 nonselected cases of these patients, all with irreversible glottis-dilating operations, were studied. Lung function tests that were performed were body-pletysmography, forced inspiratory volume (FIV1), forced expiratory volume (FEV1), peak inspiratory flow rate (PIF), peak expiratory flow rate (PEF) and resistance of the airways (RAW). The FEV1, FIV1, PEF and PIF all improved following irreversible glottis-dilating operations. The RAW was remarkably decreased post-operatively as compared to pre-operatively. In conclusion, the airways of patients undergoing irreversible glottis-dilation operations improved moderately to well following such surgeries. Lung function tests are an objective means of evaluating the airway before and after surgery.
Glottis↗
Effects of nasal positive-pressure hyperventilation on the glottis in normal sleeping subjects.
We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.
Adult↗
Distribution of intraepithelial nerve fibers in the feline glottis.
It is well known that the protective laryngeal closure is elicited by mechanical or chemical stimulation of the epithelium in the glottis. In this study we used light microscopic observation and relative examination of the intraepithelial nerve fibers in the glottis to clarify the perceptive mechanism using immunohistochemical methods. In the anterior glottis, a moderate number of protein gene product 9.5-immunoreactive intraepithelial nerve fibers were observed, most of which were found to be located just anterior to the vocal process. The number of fibers in the upper surface of the vocal fold was larger than that in the free edge and the lower surface. Only a few calcitonin gene-related polypeptide-immunoreactive fibers were seen, and substance P-immunoreactive fibers were rarely seen. On the other hand, a dense distribution of protein gene product 9.5-immunoreactive nerve fibers was observed throughout the epithelium of the posterior glottis. The number of calcitonin gene-related peptide-immunoreactive fibers was about 20% that of protein gene product 9.5-immunoreactive fibers, whereas the number of substance P-immunoreactive fibers was only 1% to 2%. The results of this study suggest that possible existence of regional differences in the perceptive mechanism between the anterior and posterior glottis.
Animals↗
Intraglottal pressure profiles for a symmetric and oblique glottis with a divergence angle of 10 degrees.
Human phonation does not always involve symmetric motions of the two vocal folds. Asymmetric motions can create slanted or oblique glottal angles. This study reports intraglottal pressure profiles for a Plexiglas model of the larynx with a glottis having a 10-degree divergence angle and either a symmetric orientation or an oblique angle of 15 degrees. For the oblique glottis, one side was divergent and the other convergent. The vocal fold surfaces had 14 pressure taps. The minimal glottal diameter was held constant at 0.04 cm. Results indicated that for either the symmetric or oblique case, the pressure profiles were different on the two sides of the glottis except for the symmetric geometry for a transglottal pressure of 3 cm H2O. For the symmetric case, flow separation created lower pressures on the side where the flow stayed attached to the wall, and the largest pressure differences between the two sides of the channel were 5%-6% of the transglottal pressure. For the oblique case, pressures were lower on the divergent glottal side near the glottal entry and exit, and the cross-channel pressures at the glottis entrance differed by 27% of the transglottal pressure. The empirical pressure distributions were supported by computational results. The observed aerodynamic asymmetries could be a factor contributing to normal jitter values and differences in vocal fold phasing.
Glottis↗
[The width-length quotient of the glottis as a measure of amplitude values].
The vibratory width of the glottis plays an important role in the diagnosis of functional voice disorders. The experienced examiner decides if the amplitudes of the vocal folds are normal, too small or too wide, always with regard to the length of the glottis. Therefore the width-length quotient is an adequate measurement for the vibratory width of the glottis. To standardize this quotient, we made stroboscopic measurements in 82 normal-voiced persons; 41 were female, 41 male. The pitch was in the range of the speaking voice at medium loudness. Statistical evaluation was done by box-and whisker plots. The width-length quotient of the glottis shows a minimum of 0.1 in both sexes with a maximum of 0.31 in men and 0.26 in women. The average was 0.16 in men and 0.17 in women. 50% of the width-length quotient near the median are inside the box, ranging from 0.14 to 0.2. Results on the lower part of the scale point towards a hyperfunctional voice disorder (small amplitude), while results in the upper part (0.2 and more) show a tendency towards hypofunction with comparatively wide amplitudes.
Adult↗
Clinical aspects of the posterior glottis: a review.
This paper was undertaken to distill a century of thought on the larynx, specifically in relation to the posterior glottis, an area which has only recently been recognized as a distinct part of the larynx. The review examines the following topics in relation to the posterior glottis: stenosis, granulomata, contact ulceration, reflux laryngitis, cleft larynx, aspiration and cricoarytenoid joint disease. The posterior glottis acts as a "weir" between the pharynx and larynx and so is intimately involved with diseases as they affect one area to the other. An attempt has been made to rationalize the treatments and clinical findings over the past century from the writings of many. Each section analyzes the modern and the older methods of clinical findings and treatment and provides a balance of opinion as to the most appropriate line of management for that condition. The review allows a comprehensive view of the clinical aspects of the posterior glottis to be brought into one document.
Glottis↗