The Larynx and Laryngitis

by Robert Tallitsch, PhD | May 19, 2022

Watch this short video explaining the Larynx and Laryngitis with a patient case example at the end!

Written by: Robert Tallitsch, PhD

The larynx is the most superior structure of the upper respiratory system. This Brain Builder will describe the anatomy of the larynx, followed by a discussion of laryngitis, which is a change in an individual’s voice pattern or a complete loss of the voice for a period of seven to ten days.

Larynx

The larynx opens superiorly and posteriorly into the pharynx; inferiorly it opens into the trachea. The larynx is composed of three large unpaired cartilages (thyroid, cricoid, and epiglottic), three pairs of smaller cartilages (arytenoid, corniculate, and cuneiform), a fibroelastic membrane, and several extrinsic and intrinsic muscles.

Cartilages of the Larynx

The thyroid cartilage, which does not completely surround the larynx, is composed of two plates (right and left laminae) that meet in the anterior midline, forming the laryngeal prominence, which is also termed the Adam’s Apple. The two laminae are widely separated posteriorly. The thyroid cartilage is attached to the hyoid bone superiorly by the thyrohyoid membrane. Inferiorly the thyroid cartilage is attached to the cricoid cartilage by the cricothyroid ligament.

The cricoid cartilage completely encircles the inferior portion of the larynx and articulates with the thyroid and arytenoid cartilages. This piece of cartilage, along with the thyroid cartilage, protects the portion of the larynx consisting of the vocal folds and the opening between them (termed the glottis), as well as the entrance to the trachea.

The epiglottic cartilage (or epiglottis) is a leaf-shaped piece of cartilage located posteriorly to the root of the tongue. The superior edge of the epiglottis is free, but the other epiglottic surfaces are attached anteriorly to the body of the hyoid bone, posteriorly to the thyroid cartilage, and laterally to the arytenoid cartilages.

The arytenoid cartilages are small, pyramidal-shaped cartilages located on the posterior, superior border of the cricoid cartilage. Each cartilage has an apex and a base. The apex of the arytenoid cartilages support the corniculate cartilages, while the base articulates with the cricoid cartilage.

The corniculate cartilages are small cartilages that, along with the arytenoid cartilages, play a role in the opening and closing of the glottis, and the production of sound.

Finally, the cuneiform cartilages are small, rod-shaped cartilages located within the epiglottic fold, providing support for that fold.

Ventricular and Vocal Folds of the Larynx

The ventricular folds (ventricular ligaments) are folds of mucous membrane that curve inferiorly into the lumen of the larynx, connecting the thyroid cartilage to the arytenoid cartilages. These rather inelastic folds prevent foreign objects from entering the glottis, thereby protecting the vocal folds. Because the ventricular folds are not involved in the production of sound they are sometimes referred to as “false vocal cords.”

Another pair of mucous membrane folds, the vocal folds, are found immediately inferior to the ventricular folds and project into the lumen of the larynx from its side walls. These vocal folds are also connected to the thyroid cartilage anteriorly and the arytenoid cartilages posteriorly. These vocal folds, which are involved in the production of sound, are termed the “true vocal cords.”

Muscles of the Larynx

The larynx possesses two sets of muscles: extrinsic muscles and intrinsic muscles. The extrinsic muscles attach the larynx to the hyoid bone or the pharynx. These muscles raise or lower the larynx during the production of sound (phonation), or during the process of swallowing (deglutition).

Intrinsic laryngeal muscles attach to the cartilages and ligaments of the larynx. These muscles modify the size of the glottis and change the tension placed upon the vocal folds, thereby altering the pitch of any sounds made by the vocal folds.

Laryngitis

Laryngitis is an inflammation of the vocal folds. This inflammation alters the way the vocal folds come together and, as a result, alters the sound of the voice. Laryngitis is often accompanied by throat pain, pain when talking, and/or pain when swallowing.

Laryngitis is diagnosed when the patient experiences either a change in his/her voice pattern or a complete loss of the voice for a period of seven to ten days.

A viral infection is the most common cause of laryngitis. Other causes of laryngitis include:

straining the voice, such as speaking too loudly or shouting for a prolonged period of time,
dehydration,
secondary laryngeal infection resulting from a sinus or oral infection,
smoking or vaping,
laryngeal irritation resulting from gastroesophageal reflux, and/or
various autoimmune disorders.

Some individuals seem to be more prone to experiencing laryngitis than others. Such individuals are thought to experience asymptomatic, chronic, low-grade viral infections (infections without visible symptoms) more frequently and, therefore, experience laryngitis more frequently and more severely than others.

Key Terms:

Thyroid cartilage - One of the three large, unpaired cartilages of the larynx.

Cricoid cartilage - One of the three large, unpaired cartilages of the larynx. This cartilage completely encircles the inferior portion of the larynx.

Extrinsic muscles of the larynx - Muscles of the larynx that connect the larynx to the hyoid bone or the pharynx.

Intrinsic muscles of the larynx - Muscles that interconnect the cartilages of the larynx and alter the size of the glottis and the tension on the vocal folds.

False vocal cords - The ventricular vocal folds of the larynx; these vocal folds do not participation in the production of sound.

Arytenoid cartilages - Small, pyramidal-shaped cartilages situated on the posterior, superior border of the cricoid cartilage. The apex of the arytenoid cartilages support the corniculate cartilages, while the base articulates with the cricoid cartilage.

Epiglottic cartilage - Also termed the epiglottis. A leaf-shaped piece of cartilage located posteriorly to the root of tongue. The superior edge of the epiglottis is free, but the other epiglottic surfaces are attached anteriorly to the body of the hyoid bone, posteriorly to the thyroid cartilage, and laterally to the arytenoid cartilages.

Laryngitis - An inflammation of the vocal folds.

Questions:

True or False? A viral infection is the most common cause of laryngitis.
A: True
Which small cartilages, along with the arytenoid cartilages, play a role in the opening and closing of the glottis, and the production of sound?
A: Corniculate cartilages
Which cartilages of the larynx are small and rod-shaped, are located within the epiglottic fold, and provide support for that fold?
A: Cuneiform cartilages
Which of the cartilages of the larynx is commonly called the Adam’s Apple?
A: Thyroid cartilage
True or False? The vocal folds are located superiorly to the ventricular folds within the larynx.
A: False. The vocal folds are located inferiorly to the ventricular folds within the larynx.
Which folds (ventricular or vocal) of the larynx are connected to the thyroid cartilage anteriorly and the arytenoid cartilages posteriorly?
A: Both the ventricular and vocal folds of the larynx connect to the thyroid cartilage anteriorly and the arytenoid cartilages posteriorly.
Which cartilages of the larynx are small, pyramidal-shaped cartilages that are found on the posterior, superior border of the cricoid cartilage?
A: Arytenoid cartilages
True or False? Intrinsic laryngeal muscles connect the larynx to the hyoid bone.
A: False. Intrinsic laryngeal muscles interconnect the cartilages of the larynx.
True or False? Some individuals seem to be more prone to experiencing laryngitis than others. Such individuals are thought to experience asymptomatic, chronic, low-grade viral infections (infections without visible symptoms) more frequently and, therefore, experience laryngitis more frequently and more severely than others.
A: True
List 3 conditions other than a virus that can cause laryngitis.
A: Any of the three causes below would be an appropriate answer:
- straining the voice, such as speaking too loudly or shouting for a prolonged period,
- dehydration,
- secondary laryngeal infection resulting from a sinus or oral infection,
- smoking or vaping,
- laryngeal irritation resulting from gastroesophageal reflux, and/or
- various autoimmune disorders.

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