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Larynx

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LARYNX ANATOMY

The larynx is commonly referred to as the “voice box.” It continues the basic line of conduction that leads the laryngophraynx into the trachea. Level with the fourth through the sixth vertebrates, the larynx is located along the anterior midline of the neck. The larynx is responsible for two basic functions, to protect the trachea and the lungs from food and fluids as well as permitting the passage of air into the respiratory system. The larynx is also vital in the production of sound, and has a triangular-box-like shape.

LARYNX STRUCTURE

Nine various cartilages create the structure of the larynx. Three of those nine cartilages are larger and unpaired while the remaining ones are paired and smaller. The anterior thyroid cartilage is the largest of the framework. The “Adam’s apple” is a prominent point of this structure, created by the vertical anterior ridges of the larynx cartilage. This particular cartilage structure is affected by the hormones of the male pubescent cycle and tends to become more prominent in the male body than the female body.

Hyaline cartilage creates the basic framework for the epiglottis. The epiglottic cartilage is shaped like a spoon. The epiglottis is resides behind the tongue’s root and is responsible for assisting in closing the closing the laryngeal opening (the glottis) while swallowing.

Cricoid cartilage creates the lower end of the larynx. The ring shaped, unpaired cartilage is responsible for adjoining the thyroid cartilage with the trachea which rests below.

Above the cricoid cartilage and just behind the thyroid, the vocal folds are attached to the arytenoid cartilages. These smaller, paired cartilages create the posterior attachment for the vocal folds.

LARYNX DIAGRAM

Larynx
Image: Larynx


Closely related to the arytenoid cartilages are the two other paired cartilages, the corniculate and the cuneiform cartilages, are smaller accessory cartilages. These aid in the structural support of the entire system.

Along the upper opening of the larynx and from the anterior cartilage of the thyroid to the posterior paired arytenoid cartilage there are two strong bands made from connective tissue which stretch the distance of these. These are known as true vocal cords (vocal folds) and false vocal cords (vestibular folds). The true vocal cords are supported structurally by the vestibular folds. The epithelial lining of the vestibular folds creates a constant source of mucous to keep the folds from over drying. The vestibular folds are devoid of the capability to produce sound. Sound production is the responsibility of the vocal folds. The vocal folds accomplish this through vibration. Additionally, the vocal folds are lined with stratified squamous epithelial cells. Adversely, the remainder of the larynx is lined with pseudostratified ciliated columnar epithelial cells. This type of anatomical design is vital when considering the vast force of vibration associated with vocalization. Equally as vital to the entire process of breathing, sound, and eating would be the laryngeal muscles, which control the glottis in swallowing and during speech.

LARYNX FUNCTIONS

The laryngeal muscles are segregated into two different groups, depending on their designed function. The muscles which are designed to lift the larynx during the act of swallowing are referred to as the extrinsic muscles. When their counterpart, the intrinsic muscles contract, they are capable of altering the length, position, and tension of the vocal folds, creating variances in sound. When air passes over the vocal folds, their position determines the sound and pitch of the vocalization. Rapid, high pitch vocalizations are caused by tighter vocal folds. Lower, melodic vocalizations are caused by looser vocal folds. Adult male bodies are equipped with vocal folds which are thicker and longer and thus create lower toned vocalizations. This is due to slower vibrations. The force in which the air is generated over the vocal folds determines the volume of the vocalization. Whispering results in vocal folds which do not vibrate at all.

The larynx is responsible for creating the origin of sound. However, it takes a combination of other various structures to produce recognizable speech. Constricting the walls of the pharynx creates the common vowel sounds. Voice requires resonation, which is provided by the pharynx, the oral cavity, nasal cavity, and the paranasal sinuses. Controlled movements of the tongue and lips create the recognizable speech patterns humans can understand.
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