|Year : 2022 | Volume
| Issue : 4 | Page : 221-226
The aging larynx: An anatomical perspective
Deepa Devadas1, Raghunath Shahaji More1, Chetan Sahni1, Mayank Gupta2, Amit Kumar Nayak1, Anand Mishra1
1 Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
2 Department of Forensic Medicine and Toxicology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
|Date of Submission||03-Sep-2022|
|Date of Decision||28-Oct-2022|
|Date of Acceptance||06-Dec-2022|
|Date of Web Publication||27-Dec-2022|
Dr. Amit Kumar Nayak
Department of Anatomy, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
There has been a striking increase in the geriatric population worldwide over the last few decades. As the aging process continues to alter functioning of all body systems, the human voice is also significantly affected. The senile voice is characterized by its changes in pitch, hoarseness, tremulousness, and breathiness with reduced harmonics and intensity. Such phonatory changes in the elderly may hinder effective communication, thus bringing down their confidence levels and impairing their quality of life. These characteristic features that distinguish the senile voice from younger speakers are accompanied by age-related changes in the organ of phonation, the larynx. The summative morphological and structural changes occurring in the elderly larynx have been referred to as “Presbylarynx.” The present review article is an attempt by the authors to explore the various anatomical age-related changes occurring in the larynx that may be responsible for altered vocal function in the elderly. An improved understanding of the anatomical basis of the aged voice can give further directions into the management of vocal disorders and improved speech performance in the elderly.
Keywords: Aging larynx, phonation, vocal folds
|How to cite this article:|
Devadas D, More RS, Sahni C, Gupta M, Nayak AK, Mishra A. The aging larynx: An anatomical perspective. J Indian Acad Geriatr 2022;18:221-6
|How to cite this URL:|
Devadas D, More RS, Sahni C, Gupta M, Nayak AK, Mishra A. The aging larynx: An anatomical perspective. J Indian Acad Geriatr [serial online] 2022 [cited 2023 Feb 8];18:221-6. Available from: http://www.jiag.com/text.asp?2022/18/4/221/365773
| The Aging Larynx – An Anatomical Perspective|| |
The voice is a distinctive part of personality and forms a unique feature of the individual's identity. Even in the absence of pathologies causing voice disturbances, voice changes in the elderly are a natural consequence of the aging process. The percentage of the elderly population has considerably increased worldwide in the recent past. It is estimated that the global population of the elderly will reach 1500 million by 2050. This can be largely attributed to increased life span subsequent to improved health-care facilities. The key to successful aging encompasses three principal components: low risk of disease and disease-related disability; maintenance of high mental and physical function; and continued engagement with life, which includes relations with others and productive activity, either paid or volunteered. The senescent voice can be clearly distinguished from that of younger individuals by its hoarseness, tremulousness, weakness, and altered pitch.
As aging progresses, the changes in voice include: loss of vocal power, reduced harmonics and vocal range, tremor, reduced speech rate, increased degree of breathiness, pneumophonic in-coordination, decreased vocal intensity, and maximum phonation time. Such vocal changes can significantly impair effective communication and bring down the quality of life among the elderly. Senior citizens may find it increasingly difficult to socialize due to voice constraints, which can lead to embarrassment and reduced confidence levels. For those still employed, forced early retirement may be a consequence of diminished vocal effectiveness. The summative effect of these vocal issues in the elderly can negatively impact their successful aging process, with lasting physiological, psychological, and social implications.
These changes in the senile voice occur due to anatomical and physiological changes in the organ of phonation, the larynx. The term “Presbyphonia,” now well recognized in scientific literature, refers to the sequence of physiological events related to the process of senility of the vocal folds and aging of the larynx. Studies have reported the prevalence of presbyphonia to range from 7.3% to 29%.,, The term “Presbylarynx” has been used to represent various anatomical and physiological changes in the larynx due to the aging process, which results in the senescent voice. This article is an attempt by the authors to explore age-related anatomical changes which are involved in the etiogenesis of presbylarynx and the subsequent development of presbyphonia.
| Intrauterine Development of Larynx|| |
The earliest indications of larynx formation appear during the 4th week of intrauterine development, with the appearance of the laryngotracheal groove in the floor of the primitive pharynx. The laryngotracheal groove evaginates by the end of the 4th week to form a pouch-like laryngotracheal diverticulum. The laryngotracheal diverticulum appears as an endodermal outgrowth in the ventral wall of the foregut, just below the fourth pharyngeal pouch with its endodermal lining forming the lining epithelium and glands of the larynx.,, The tracheoesophageal septum is formed within the laryngotracheal diverticulum at the end of the 5th week which partitions the developing pharynx. The opening of the laryngotracheal tube into the pharynx develops into the primordial laryngeal inlet. The laryngeal cartilages and musculature develop from the 4th and 6th pairs of pharyngeal arches, with contribution from mesenchyme derived from neural crest cells during the 5th–8th weeks of development.,, The floor of the primitive pharynx, at the level of the fourth pouch and the site of origin of the laryngotracheal diverticulum, develops into the glottis. The segment of foregut consisting of the primitive laryngopharynx becomes the supraglottic part, and the cephalic portion of the laryngotracheal diverticulum gives rise to the infraglottic part of the larynx. Paired lateral arytenoid swellings develop around the laryngeal inlet and grow toward the tongue and along with anterior median epiglottic swelling, converting the primordial glottis into a T-shaped laryngeal inlet.,, A triangular depression, the laryngeal cecum, appears between these three swellings which forms the primary origin of the laryngeal vestibule. An epithelial lamina, formed by proliferation of laryngeal epithelium and mesenchyme during the 6th week, almost completely occludes the primitive laryngopharynx, except for a narrow communication between the hypopharynx and infraglottis which becomes the dorsal pharyngoglottic duct.,, As recanalization of the laryngeal lumen begins during the 10th week of development, a communication is established between the laryngeal cecum and dorsal pharyngoglottic duct, connecting the supraglottic and infraglottic parts of the larynx. The laryngeal ventricle is formed during this recanalization process, with outgrowths from lateral aspects of the laryngeal cecum that develop into false and true vocal folds., The larynx attains the same features recognizable at birth by the 3rd month of intrauterine life. A flowchart indicating the sequence of these embryological events leading to the formation of the larynx has been presented in [Figure 1].
| Postnatal Development|| |
After birth, the larynx descends in the neck with gradual lengthening of the vocal cords and further increase in the dimensions of the laryngeal cavity. The growth pattern is rapid during the first 3 years of life, following which it slows down till puberty. The final position of the cricoid cartilage at the level of C6/C7 vertebra is reached by 15 years of age. At birth, the length of the vocal cord is 2.5–3.0 mm and it reaches its adult size by 10–14 years of age measuring about 11–15 mm in females and 17–21 mm in males., After puberty, the male larynx enlarges considerably in comparison to the female with increase in size of all cartilages, particularly the thyroid cartilage which doubles in its sagittal diameter and continues to grow till 40 years of age. These changes contribute to the distinctive quality and pitch of male and female voices.
| Adult Larynx|| |
The adult larynx thus formed comprises a skeletal framework made up of cartilages that are interconnected by ligaments and membranes and moved by various muscles. The laryngeal cartilages include the unpaired median thyroid, cricoid, and epiglottic cartilages and the paired arytenoid, cuneiform, corniculate, and tritiate cartilages. The thyroid, cricoid, and the greater part of the arytenoid cartilages are composed of hyaline cartilage which calcifies with age. The corniculate, cuneiform, tritiate, and epiglottic cartilages as well as the apices of arytenoid are composed of elastic cartilage, with little tendency to calcify. The thyroid, cricoid, and arytenoid cartilages are held together by synovial cricothyroid and cricoarytenoid joints. The skeletal framework of the larynx is joined to surrounding structures by extrinsic membranes, mainly the thyrohyoid membrane, and interconnected by intrinsic ligaments, namely, the conus elasticus, quadrangular, and cricothyroid membranes.
The laryngeal cavity extends from the laryngeal inlet to the lower border of the cricoid cartilage, where it becomes continuous with the trachea. The upper vestibular and lower vocal folds divide the laryngeal cavity into upper, middle, and lower portions. This middle portion constitutes the laryngeal ventricle. The median aperture between the upper pair of vestibular folds is the rima vestibuli. The lower pair of folds are the true vocal folds (or vocal cords), and the fissure between them is the rima glottidis or glottis. The true vocal folds are the primary source of phonation. The supraglottis refers to all those parts of the larynx that lie above the glottis and thus comprises the laryngeal inlet, the laryngeal vestibule, and the vestibular folds. The infraglottis or subglottis refers to the region below the glottis that extends till the inferior border of the cricoid cartilage.
| Physiology of Phonation|| |
The production of speech requires four components which include (a) power source, i.e., lungs; (b) phonation which is the generation of sound by vocal fold vibration; (c) resonance refers to the amplification and modulation of that sound by vibration in the structures above the larynx (pharynx, oropharynx, nasopharynx, oral cavity, and nasal passages); and (d) articulation which includes the complex interaction of lips, teeth, tongue, palate, and pharynx to shape and modify the sound. The phonatory organs that are involved in voice production are the lungs and larynx. The driving air pressure in the lungs and vocal fold vibrations of the larynx together adjust the pitch, loudness, and quality of the voice, and further generate prosodic patterns of speech. During speech production, the respiratory pattern changes to a longer expiratory phase with a shorter inspiratory phase during quiet breathing. As air is expelled upward from the lungs by elastic recoil and coordinated actions of inspiratory and expiratory muscles, subglottic air pressure generated below the vocal folds causes them to open up and vibrate, thus producing the sound wave., The glottic cycle is thus divided into (i) closed phase where air pressure builds up below the vocal folds; (ii) opening phase when the subglottic pressure reaches a point where it exceeds muscular opposition and the glottic slit is forced open; (iii) open phase when the vocal folds are completely open and air column rushes through the vocal folds producing the sound wave; and (iv) closing phase in which after release of the puff of air, there is a reduction of subglottic pressure and the vocal cords approximate each other again due to myoelastic forces. The physiology of phonation has been explained by two theories, namely, (i) myoelastic-aerodynamic theory of phonation and (ii) cover-body theory of vocal fold vibration.
| Onset of Aging in Cartilage and Bones|| |
The onset of aging in the larynx begins in early adulthood, when the laryngeal cartilages begin to ossify. Histologically, both hyaline and elastic cartilages contribute to the laryngeal skeleton. The thyroid, cricoid, and the major portion of the arytenoid cartilages are hyaline while the epiglottis, corniculate, and cuneiform cartilages and the apical parts of the arytenoids are elastic cartilages. Calcification/ossification changes occur in the hyaline cartilages and do not affect elastic cartilages of the larynx. This process of ossification usually starts at around 18 years of age initially involving the posteroinferior parts of the thyroid cartilage, and subsequently spreads to the remaining cartilages. The rate of ossification is found to be comparatively slower in females than males and occurs mainly by endochondral ossification.,,, According to Turk, the first signs of calcification occur along the inferior border of the thyroid laminae in the region of the insertion of the cricothyroid muscle and subsequently spread upward near the posterior border of the laminae close to the oblique line, another major site of muscle attachment. Within the cricoid, the lamina and posterior part of the arch become ossified before the anterior part, which may be due to mechanical forces generated by the posterior and the lateral cricoarytenoid muscles. These findings suggest that the sites of muscle attachments in laryngeal cartilages may be more predisposed to earlier onset of calcification changes. Turk also mentions the earlier occurrence of calcification in the male in the region of the laryngeal prominence, suggesting that sites of greater mass may also be preferential sites for calcification and ossification. Following the thyroid and cricoid cartilages, the next cartilage to ossify is the arytenoid where ossification begins at the base and spreads to the rest of the cartilage. The vocal process of the arytenoid cartilage appears to become more protuberant, especially in elderly women. Ossification of the larynx is completed by the seventh decade of life. The age-related calcification of the laryngeal cartilages, especially in the region of the posterior glottis and the anterior commissures, can lead to stiffening of the attachment of vocal folds which subsequently alters the fundamental frequency or the pitch of the voice.,
| Aging in Musculature|| |
The laryngeal musculature also undergoes significant atrophic changes with age. Age-related sarcopenic changes cause a decline in the number and diameter of muscle fibers in the laryngeal musculature. The thyroarytenoid muscle appears to be particularly affected resulting in voice changes.,, The thyroarytenoid muscles (i) shorten and relax the vocal ligaments and (ii) approximate the vocal folds to aid closure of the rima glottides. The medial part of the thyroarytenoid muscle is the vocalis muscle. Relaxation of the posterior parts of the vocal ligaments brought about by the vocalis muscles, combined with tension in the anterior parts of the ligaments, is responsible for raising the pitch of the voice. Aging of the vocalis muscle begins in the 6th decade and is characterized by a striking increase of endomysial connective tissue, aggregations of mitochondria, and increase of mitochondrial enzyme activity in the subsarcolemmal regions, as in so-called ragged red fibers. Age-related mutations in mitochondrial DNA lead to overproduction of dysfunctional mitochondrial units, which may have a detrimental effect on the contractility of the thyroarytenoid muscle., Vocal musculature atrophy induced by these changes results in partial closure of the glottis and glottic incompetence which result in vocal symptoms such as breathiness and decrease in loudness of the voice.
| Aging Changes in Vocal Folds|| |
The vocal folds of the elderly also show distinctive age-related changes. The characteristic laryngoscopic finding in the senile larynx is the occurrence of vocal fold bowing.,,,,, This occurs as a result of atrophic changes in the vocal folds and the associated musculature. The vocal folds of the senile larynx demonstrate yellowish or greyish discoloration with frequent occurrence of vocal fold edema.,,, With aging, vocal folds show epithelial atrophy, an increase in the number of collagen fibers, decrease in the quantity of elastic fibers, and reduced hyaluronic acid content in the lamina propria of the vocal ligament.,,,,,, In addition, there is noted to be a decrease in epithelial cell density as well as thickness of lamina propria as aging advances., The lamina propria with its intricate layered structure allows the vocal folds to vibrate with consistency and control. The rise in collagen content with decrease in elastic fibers of the lamina propria increases the rigidity of vocal folds, thus reducing their vibratory wave. This may contribute to the characteristic hoarseness of the senescent voice. In addition, vocal fold atrophy contributes to glottal air escape during phonation, leading to breathiness and decrease in maximum phonation time. Vocal fold edema may also bring down the fundamental frequency and lower the pitch of the voice.,
| Aging in Laryngeal Glands|| |
The laryngeal glands also play a significant role in phonatory function by keeping the mucosa over the vocal folds moist and lubricated with their secretions. Age-related involution of laryngeal glands has been found to predominantly affect the supraglottic part of the larynx. Aged laryngeal glands show atrophy of glandular acini with reduced content of secretory granules in serous cells and mucigen droplets in mucous cells as compared to younger adults. Furthermore, there is a change in the ratio of glandular distribution with more number of mucous glands as compared to serous glands, especially in the supraglottic part., However, the overall secretion of mucus is reduced and its viscosity changes affecting mucociliary transport in the aged larynx. The secretory products of serous acini of aged laryngeal glands show a difference in quality with reduced protein material. Decreased secretion by the laryngeal glands leads to dryness of throat, which is often experienced by the elderly population. The reduced mucus production may impair mucociliary movement and hamper removal of irritants from the laryngeal mucosal surface. As a result, elderly individuals might experience a need for repetitive throat clearing during the course of conversation.
| Aging in Laryngeal Nerves|| |
Age-related changes in the laryngeal nerves and neuromuscular coordination may further add to changes in phonatory function in the elderly. Studies have shown significant age-related loss of myelinated fibers in superior and recurrent laryngeal nerves in people aged >60 years.,, This can result in impaired laryngeal muscle tone as a result of reduced neuromuscular transmission and coordination. This may lead to laryngeal muscle flaccidness and produce the typical voice changes that characterize presbyphonia. The resultant dystonia of the musculature leads to laryngeal tremor and vocal instability, resulting in the characteristic jitteriness and shimmer of the aged voice.,,
| Other Aging Factors|| |
Degenerative changes in the cricoarytenoid joint may also act as a contributory factor to voice impairment in the elderly. Studies have demonstrated age-related chondrocyte proliferation with altered collagen synthesis and fibrillation of the joint surface., These degenerative changes may impair movements of the arytenoid cartilage, which provides attachment to the vocal ligament. As a result, there may be impaired approximation of the vocal ligaments during phonation. The resultant air leakage due to the loose approximation of vocal ligaments can cause a considerable decrease in voice intensity, diminishing voice quality. It is also thought that the larynx may descend lower in the neck with advanced age as a result of stretching of ligaments and atrophy of the strap muscles of the neck. This may result in aged individuals assuming alternative articulatory positions that may affect the resonance characteristics of their voice.,
All these age-related morphological and structural changes affecting the human larynx play a key role in voice transitions that occur in the geriatric population. As phonation plays a crucial role in communication, voice changes in older adults can affect social behavior resulting in withdrawal, anxiety, and depression. The prevalence of vocal disorders in population aged 60 years and above has been found to range from 4.8% to 29.1% and is depicted in [Table 1],,.
|Table 1: Epidemiological prevalence of vocal complaints in various elderly populations|
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Although many elderly people adapt to changes in their vocal function, a certain portion do develop voice disorders that may cause severe challenges and hinder their quality of life. Understanding the anatomical changes occurring in the aging larynx is a key step in the evaluation of voice disorders in such patients and can help in planning treatment strategies that can further improve their quality of life.
Financial support and sponsorship
Funding required for this article was made available by Banaras Hindu University under IoE seed grant to Dr. Amit Kumar Nayak, letter no. R/ Dev/D/IoE/Seed Grant/2020-21/, dated 01.07.2020.
Conflicts of interest
There are no conflicts of interest.
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