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ANATOMY OF THE VOCAL CORDS OR FOLDS - II
There are four vocal cords, two internal pairs called True cords , and an upper pair, called False cords (vestibular folds). They are located inside our larynx, placed in a V-shape and attached at their intersection to the arytenoid cartilage , and anteriorly to the thyroid cartilage .
Its external borders join the muscles of the larynx and in its internal part there is a free space for the passage of air, either for breathing or for phonation. This space is called the glottis.
CHARACTERISTICS OF THE VOCAL STRINGS OR FOLDS
The vocal folds are viscoelastic , made up of several layers with specific characteristics and properties. * These properties can be altered due to cold, dehydration, medications, illness, in a way that will affect their vibration and the quality of our voice.
LAYER COMPOSITION
The outer part of the vocal folds is covered by a layer of epithelial tissue and mucosa. This acts as a protective layer, reducing the impact that it may suffer, product of the daily vibration when speaking or singing; of mechanical traction injuries, chemical damage, dehydration, infections, etc. This type of epithelium must be continuously moistened to avoid dryness.
The mucosa is the outermost part of the vocal folds and, therefore, is the one that is exposed and receives the greatest wear.
The basement membrane supports the epithelium and attaches it to the superficial layer of the "lamina propria." The basement membrane is formed by fibroblasts that participate in the healing and restoration of epithelial cells and collagen (protein capable of forming flexible fibers but resistant to traction )
The superficial lamina propria is the first layer and forms part of the vocal mucosa. The mucosa slides over the ligament independently in its vibration. It is an elastic structure composed, above all, of collagen. Due to the characteristics of the mucosa, it is where most voice disorders originate.
The thyroarytenoid muscle is a muscle that is parallel to the vocal cords and its function is to relax the vocal folds. Its ends are attached to the cartilages Thyroid and Arytenoid. The vocalis muscle is the superior portion of the thyroarytenoid muscle and is primarily involved in voice production.
It consists of two parts with different couplings and directions. Its main use is to attract the cartilages together, and thus relax and shorten the vocal cords. But, due to the connection with the vocal cords, this part acts separately, causing its lateral part to also rotate the arytenoid cartilage inwards, bringing the two vocal cords together.
The base of the tongue is attached to the hyoid bone and to the epiglottis , when the tongue contracts at its lowest part, the hyoid bone rises.
The styloglossus muscle is an elongated muscle and has its origin in the part of the mandible, reaching the lateral edges of the middle of the tongue, until it reaches the central part.
The hyoglossus muscle connects with the hyoid bone towards the lateral borders of the tongue to the midline. It depresses and detracts from the language.
The palatoglossal muscle connects with the edges of the tongue in the arc where the bell is located, the function of this muscle is to raise the back of the tongue, raising it towards the palate and when it contracts it narrows the “ism of the maw”.
We see here the great importance of learning to relax all these muscles and activate them correctly to avoid tensions or obstacles in the emission of sound.
*Continuous exercise is recommended to coordinate them naturally.
Bibliography: Sottovoce
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