As an important component of the vocal folds, the paired vocal cords primarily serve to form the human voice. Colloquially, the vocal folds are often referred to as the vocal cords.
What are the vocal cords?
Schematic diagram showing the anatomy of the vocal cords and their various diseases. Click to enlarge. The vocal cord (ligamentum vocale) is an elastic ligament that extends from the posterior surface of the thyroid cartilage (cartilago thyreoidea) to the processus vocalis of the stellate cartilage (cartilago arytaenoidea) and is located in the middle region of the larynx. The paired vocal cords, like the vocal muscles (Musculus vocalis), are located in the vocal folds ( Plicae vocales) and regulate the shape and tension of the vocal folds as well as the glottis (Rima glottidis) via the contractile activity of the Musculi vocalis and other involved laryngeal muscles, and thus the formation of the voice (technically also phonation).
Anatomy and structure
The vocal cords model the medial (middle) edge of the plicae vocales as well as the rima glottidis (glottis) and are superimposed on the vocal muscles, which are also paired. The muscle fibers of the musculi vocalis merge with and radiate into the vocal cords. The section of the vocal cords located toward the laryngeal lumen is covered with mucosa of squamous epithelium. The recurrent nerve, as a branch of the vagus nerve, innervates (supplies) the muscles of the larynx responsible for vocal cord movement, which include the vocalis muscle. The vocal folds are often referred to in everyday language as vocal cords, although the two actual vocal cords are formed only by the epithelium resting on the vocalis muscle and the upper layers of fibers.
Functions and tasks
The primary function of the vocal cords is voice production or phonation. When the ligaments are caused to vibrate by the airflow during exhalation, sounds are produced. The frequency of these vibrations, and thus the fundamental pitch, are adjusted by changes in the state of tension of the vocal cords. Thus, the vocal folds and vocal cords are tense for the articulation of high tones with the help of the laryngeal muscles, while slack muscles produce low tones. Since men generally have longer vocal cords, they have a deeper voice. The volume of the tones, on the other hand, is not controlled by the vocal cords, but by the strength of the airflow. The vocal timbre and fullness is produced by the resonance chamber formed by the pharynx and the oral and nasal cavities. During inhalation, the glottis formed by the vocal cords and lips is wide open, allowing the airflow to pass through here and continue via the trachea into the lower airways. In addition, the glottis, controlled by the vocal cords and muscles, acts as a protective barrier through which the opening and closing of the trachea can be consciously controlled, which plays a role, for example, when moving underwater.
Diseases and complaints
Because the vocal cords do not have their own mucus-producing glands, they can dry out quickly, especially in winter when the heating air is dry. As a result of dehydration, the vocal cords become irritated, giving the voice a scratchy and rough coloration. In addition, a scratchy and rough voice may indicate a lack of hydration, especially in the presence of colds that involve the throat. However, most disorders of vocal cord functionality originate from irritation and inflammation of the vocal fold mucosa. Pathological changes in the vocal folds usually affect the vocal cords as well, since these, together with the vocal muscles, largely make up the vocal folds. Thus, untreated throat infections can cause tissue neoplasms such as vocal fold polyps (tumor-like benign growths of the mucosa), which limit the functionality of the vocal cords. Vocal fold polyps are usually manifested by diplophonia (, also biphony or double-tone) and hoarseness, but can also lead to a risk of suffocation if they are more pronounced.In addition, vocal fold nodules, which are also called crying nodules, because they can be attributed to a permanent malfunction and/or overload of the vocal cord apparatus, and are characterized by elevations at the edges of the vocal folds, can affect the vocal cords.Furthermore, permanent cigarette smoke and allergic reactions can irritate the vocal cords and lips. If the vocal folds are no longer able to close or open completely as a result of surgery on the thyroid gland, paralysis of the vocal cord nerve, a tumor or a viral infection, this is referred to as vocal cord paralysis, which can be accompanied by impaired phonation (especially hoarseness) and breathing problems. Furthermore, vocal fold edema (Reinke edema) can impair the functioning of the vocal cords and cause hoarseness, voicelessness, and breathing problems.
