Sensory Innervation of the Larynx and the Search for Mucosal Mechanoreceptors

Abstract

Purpose The larynx is a uniquely situated organ, juxtaposed between the gastrointestinal and respiratory tracts, and endures considerable immunological challenges while providing reflexogenic responses via putative mucosal mechanoreceptor afferents. Laryngeal afferents mediate precise monitoring of sensory events by relay to the internal branch of the superior laryngeal nerve (iSLN). Exposure to a variety of stimuli (e.g., mechanical, chemical, thermal) at the mucosa–airway interface has likely evolved a diverse array of specialized sensory afferents for rapid laryngeal control. Accordingly, mucosal mechanoreceptors in demarcated laryngeal territories have been hypothesized as primary sources of sensory input. The purpose of this article is to provide a tutorial on current evidence for laryngeal afferent receptors in mucosa, the role of mechano-gated ion channels within airway epithelia and mechanisms for mechanoreceptors implicated in laryngeal health and disease. Method An overview was conducted on the distribution and identity of iSLN-mediated afferent receptors in the larynx, with specific focus on mechanoreceptors and their functional roles in airway mucosa. Results/Conclusions Laryngeal somatosensation at the cell and molecular level is still largely unexplored. This tutorial consolidates various animal and human researches, with translational emphasis provided for the importance of mucosal mechanoreceptors to normal and abnormal laryngeal function. Information presented in this tutorial has relevance to both clinical and research arenas. Improved understanding of iSLN innervation and corresponding mechanotransduction events will help shed light upon a variety of pathological reflex responses, including persistent cough, dysphonia, and laryngospasm.

Brain adaptation following various unilateral vocal fold paralysis treatments: A magnetic resonance imaging based longitudinal case series

“…The middle division of this nerve internal branch is responsible for sensory innervation of the vocal folds ( Foote and Thibeault, 2021 ). Moreover, according to the synthesis written by Foote and Thibeault (2021) on the sensory innervation of the larynx, Galen’s anastomosis and/or the arytenoid plexus are highly prevalent in humans and consequently, the posterior branch of the recurrent laryngeal nerve (classically described as only motor) would play an important role in the sensory innervation of the subglottic region. That this nerve was injured on the paralyzed side and preserved on the mobile side could contribute to a greater sensory response in the left nuclei of the solitary tract.…”

“…An injury to the vagus nerve or its recurrent branch can therefore lead to the immobility of the vocal fold on the same side of the injury ( Rosen et al, 2016 ). Sensory afferents from the larynx are transmitted by the superior laryngeal nerve and probably also by sensory anastomoses with the recurrent laryngeal nerve to the nucleus of the solitary tract that is also located in the medulla oblongata ( Foote and Thibeault, 2021 ). According to a recent study ( Wang H. W. et al, 2020 ), paralysis is mainly caused, in decreasing order of prevalence, by surgery (mainly following thyroidectomy), tumors (mainly in the lung), or idiopathic causes.…”

Transcriptome Dynamics in the Developing Larynx, Trachea, and Esophagus

“…The upper aerodigestive system provides respiratory and alimentary functions for safe breathing and swallowing, with evidence of multiple reflexes integrating both systems in the developing fetus (Harding et al, 1984;Ross and Nijland, 1997;Miller, Sonies and Macedonia, 2003). The larynx is a highly reflexive effector organ for respiratory functions, with laryngeal afferents mediating precise monitoring of sensory events by relaying to the internal branch of the superior laryngeal nerve (iSLN) via dense innervation of heterologous afferent receptor subtypes (Foote and Thibeault, 2021). The laryngeal adductor response is a highly conserved sensory-afferent (iSLN) dependent reflex that results in rapid VF closure and tracheobronchial airway protection.…”

Vegetative innervation of the human vocal larynx

“…В связи с этим изучение механизмов влияния ВНС на голосовую функцию требует проведения тщательного анализа особенностей строения и вегетативной иннервации слизистой оболочки голосовых складок и тех внутригортанных мышц, которые участвуют в процессе формирования голоса. К настоящему времени существует много публикаций, посвященных иннервации мышц, определяющих величину голосовой щели и степень натяжения голосовых складок, но они в основном описывают внутригортанные чувствительные (афферентные) и двигательные (эфферентные) нервные окончания [3][4][5]. При этом не придается значения тому, что существенную часть эфферентных путей составляют вегетативные нервные волокна, осуществляющие контроль над трофическим состоянием тканевого субстрата [6] и оказывающие непосредственное влияние на мышцы гортани путем изменения метаболизма мышечных клеток [7].…”