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Vocalis Muscle (vocali + muscle)
Selected AbstractsThe highly specialized vocal tract of the male Mongolian gazelle (Procapra gutturosa Pallas, 1777 , Mammalia, Bovidae)JOURNAL OF ANATOMY, Issue 5 2003R. Frey Abstract The entire head and neck of a wild adult male Mongolian gazelle (Procapra gutturosa) was dissected with special reference to its enlarged larynx. Two additional adult male specimens taken from the wild were analysed by computer tomography. The sternomandibularis, omohyoideus, thyrohyoideus and hyoepiglotticus muscles are particularly enlarged and improve laryngeal suspension and stabilization. The epiglottis is exceptionally large. A permanent laryngeal descent is associated with the evolution of an unpaired palatinal pharyngeal pouch. A certain momentary descent seems to occur during vocalization. The high lateral walls of the thyroid cartilage are ventrally connected by a broad keel. The large thyroarytenoid muscle is divided into two portions: a rostral ventricularis and a caudal vocalis muscle. A paired lateral laryngeal ventricle projects between these two muscles. The massive vocal fold is large and lacks any rostrally directed flexible structures. It is supported by a large cymbal-like fibroelastic pad. Vocal tract length was measured in the course of dissection and in computer tomographic images. Two representative spectrograms, one of an adult male and one of a juvenile, recorded in the natural habitat of the Mongolian gazelle are presented. In the spectrograms, the centre frequency of the lowest band is about 500 Hz in the adult male and about 790 Hz in the juvenile. The low pitch of the adult male's call is ascribed to the evolutionary mass increase and elongation of the vocal folds. In the habitat of P. gutturosa a call with a low pitch and, thus, with an almost homogeneous directivity around the head of the vocalizing animal may be optimally suited for multidirectional advertisement calls during the rut. The signal range of an adult male's call in its natural habitat can therefore be expected to be larger than the high-pitched call of a juvenile. [source] Development and Maturation of the Pediatric Human Vocal Fold Lamina Propria,THE LARYNGOSCOPE, Issue 1 2005Christopher J. Hartnick MD Abstract Objective: To identify characteristic patterns of maturation of the human vocal fold lamina propria as it develops into a mature structure. Methods: Histologic evaluation of sectioned true vocal folds from 34 archived larynges ages 0 to 18 years using hematoxylin-eosin, trichrome, Alcian blue pH 2.5, Weigert reticular, and Miller's elastin stain. Location: Pathology department at a tertiary care children's hospital. Results: At birth and shortly thereafter, there exists a relative hypercellular monolayer of cells throughout the lamina propria. By 2 months of age, there are the first signs of differentiation into a bilaminar structure of distinct cellular population densities. Between 11 months and 5 years, two distinct patterns are seen: 1) this bilaminar structure and 2) a lamina propria where there exists a third more hypocellular region immediately adjacent to the vocalis muscle (this region is similar to the superficial hypocellular region found just deep to the surface epithelium). By 7 years of age, all of the specimens exhibit this transition between the middle and the deeper layers according to differential density of cell populations. A lamina propria structure defined by differential fiber composition (elastin and collagen fibers) is not present until 13 years of age and then is present throughout adolescence. Conclusions: Using the classic adult model of fiber composition and density to differentiate the layered structure of the lamina propria of the human vocal fold may not adequately allow for a thorough description of the process of maturation and development. Rather, distinct regions of cell density are seen as early as 2 months postpartum, and the model of cellular distribution may serve better to describe the lamina propria as it develops. Cell-signaling processes that shape the formation of the lamina propria appear to produce layered populations of differential cell density that in turn will later produce differential fiber compositions. Early development therefore can be followed by evaluating the maturation of these differing cell populations. Future studies are needed to quantify these cell distribution patterns, to study the cell signaling processes that trigger this maturation, and to correlate these findings with mechanical modeling. [source] Investigation of optimal intensity and safety of electrical nerve stimulation during intraoperative neuromonitoring of the recurrent laryngeal nerve: A prospective porcine model,HEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 10 2010Che-Wei Wu MD Abstract Background Intraoperative neuromonitoring (IONM) of the recurrent laryngeal nerve (RLN) has recently been more frequently applied in thyroid surgery. However, concerns have been raised regarding the safety and optimal intensity of electrical nerve stimulation. Methods Eight piglets were enrolled, and electrically evoked electromyography (EMG) was recorded from the vocalis muscles via endotracheal surface electrodes. The baseline EMG was measured and continuous pulsatile stimulations were performed on the vagus nerve and RLN for 10 minutes. Changes of EMG waveform and cardiopulmonary status were analyzed. Results A dose,response curve existed with increasing EMG amplitude as stimulating current was increased, with maximum amplitude elicited on vagal and RLN stimulation at <1 mA. No obvious EMG changes and untoward cardiopulmonary effects were observed after the stimulation. Conclusions Electrical stimulation is safe during IONM in this porcine model. Minimal current that required generating the maximal evoked EMG, approximately 1 mA in this study, can be selected to minimize the risk of nerve damage and cardiopulmonary effects. © 2010 Wiley Periodicals, Inc. Head Neck, 2010 [source] Changes of Extremity and Laryngeal Muscle Electromyographic Amplitudes After Intravenous Administration of Vecuronium,THE LARYNGOSCOPE, Issue 12 2008Yongbing Shi MD Abstract Objectives: To compare electromyographic (EMG) amplitude changes in extremity and laryngeal muscles after vecuronium administration and study the effects of topical lidocaine on laryngeal EMG in a swine model. Study Design: Prospective animal study. Methods: Electrically evoked EMG activities were recorded from the vocalis muscles (directly and via an EMG endotracheal tube) and from the flexor digitorum muscles before and after intravenous vecuronium administration. EMG amplitudes were followed for 30 minutes after vecuronium injection together with monitoring of limb twitches to train-of-four stimulation. The testing was repeated after a 30-minute wash-out period and with topical lidocaine. Results: EMG amplitude recovery occurred sooner and more quickly in flexor digitorum muscle than in vocalis muscles. Reappearance of four twitches corresponded to EMG amplitude recovery to about 80% of the baseline in flexor digitorum muscles and to about half-baseline size in vocalis muscles. EMG amplitudes were generally lower at the start of the second round testing than the first round, with somewhat slower recovery in vocalis muscles. Conclusions: In contrast to reports by others in human studies, extremity muscles seem to be more resistant to vecuronium at 0.1 mg/kg than laryngeal muscles in the swine. Reappearance of four twitches corresponds to 50% of laryngeal EMG recovery and indicates adequate condition for monitoring electrically evoked laryngeal EMG activities. This study is inconclusive regarding the effects of topically applied lidocaine on laryngeal EMG amplitudes. Translation of these data to humans should be done with caution. [source] | ||||||||||