In this lesson, you will learn about the structure and function associated with the larynx, which belongs to the lower respiratory tract. Specifically, this lesson will cover:
As you learned in a previous lesson, the lower respiratory tract includes the larynx, trachea, bronchial tree, alveolar ducts, and alveoli of the lungs. These structures are responsible for pulling air from the upper respiratory system, absorbing oxygen, and releasing carbon dioxide. They are also involved in vocalization and are essential for human speech. In this and the next two lessons, you will learn more about the larynx, trachea, bronchial tree, alveolar ducts, and alveoli. You will learn more about the lungs specifically in another future lesson.
1. Larynx
The larynx is a cartilaginous structure inferior to the laryngopharynx that connects the pharynx to the trachea and helps regulate the volume of air that enters and leaves the lungs. The structure of the larynx is formed by several pieces of cartilage. Three large cartilage pieces form the major structure of the larynx:
thyroid cartilage (anterior)
epiglottis (superior)
cricoid cartilage (inferior)
The thyroid cartilage is the largest piece of cartilage that makes up the larynx and it consists of two identical halves called laminae, which are plates of cartilage. The thyroid cartilage consists of the laryngeal prominence, or “Adam’s apple,” which tends to be more prominent in males. The thick cricoid cartilage forms a ring, with a wide posterior region and a thinner anterior region. Three smaller, paired cartilages—the arytenoids, corniculates, and cuneiforms—attach to the epiglottis and the vocal cords and muscle that help move the vocal cords to produce speech.
Larynx - The larynx extends from the laryngopharynx and the hyoid bone to the trachea.
The epiglottis, attached to the thyroid cartilage, is a very flexible piece of elastic cartilage that covers the opening of the trachea. When in the “closed” position, the unattached end of the epiglottis rests on the glottis.
The glottis is composed of the vestibular folds, the true vocal cords, and the space between these folds. A vestibular fold, or false vocal cord, is one of a pair of folded sections of mucous membrane. A true vocal cord is one of the white, membranous folds attached by muscle to the thyroid and arytenoid cartilages of the larynx on their outer edges. The inner edges of the true vocal cords are free, allowing oscillation (movement back and forth) to produce sound.
did you know
How do vocal cords differ between individuals?
The size of the membranous folds of the true vocal cords differs between individuals, producing voices with different pitch ranges. Folds in males tend to be larger than those in females, which creates a deeper voice.
The act of swallowing causes the pharynx and larynx to lift upward, allowing the pharynx to expand and the epiglottis of the larynx to swing downward, closing the opening to the trachea. These movements produce a larger area for food to pass through while preventing food and beverages from entering the trachea.
Vocal Cords - The true vocal cords and vestibular folds of the larynx are viewed inferiorly from the laryngopharynx.
Continuous with the laryngopharynx, the superior portion of the larynx is lined with stratified squamous epithelium, transitioning into pseudostratified ciliated columnar epithelium that contains goblet cells. Similar to the nasal cavity and nasopharynx, this specialized epithelium produces mucus to trap debris and pathogens as they enter the trachea. The cilia beat the mucus upward towards the laryngopharynx, where it can be swallowed down the esophagus.
IN CONTEXT
How Humans Produce Speech
Human speech is a complex process. First, air is brought from the lungs to the larynx following respiration. Then, phonation occurs when the vocal folds can be held open, which allows the air to pass through, this makes the vocal folds vibrate. When this occurs, the vocal folds trap and release air. When the air is released, it sends air into the pharynx, and that is the beginning of a sound wave. Articulation then occurs when airflow is shaped by the articulators in the mouth and nose. The main articulators include the tongue, lips, upper teeth, upper gum ridge (alveolar ridge), hard palate, soft palate, uvula, pharyngeal wall, and glottis.
A Child Articulates the “O” Sound
Term Pronunciation Table
Term
Pronunciation
Audio File
Laryngeal Prominence
la·ryn·geal prom·i·nence
Cricoid Cartilage
cri·coid car·ti·lage
Epiglottis
epi·glot·tis
terms to know
Larynx
The cartilaginous structure that produces the voice, prevents food and beverages from entering the trachea, and regulates the volume of air that enters and leaves the lungs.
Thyroid Cartilage
The largest piece of cartilage that makes up the larynx and consists of two identical halves called laminae, which are plates of cartilage.
Laryngeal Prominence
The region where the two halves (the laminae) of the thyroid cartilage join, forming a protrusion known as the “Adam’s apple”.
Cricoid Cartilage
The portion of the larynx, which is composed of a ring of cartilage with a wide posterior region and a thinner anterior region; attached to the esophagus.
Epiglottis
The leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing.
Glottis
The opening between the vocal folds through which air passes when producing speech.
Vestibular Fold
The part of the folded region of the glottis composed of mucous membrane; supports the epiglottis during swallowing.
True Vocal Cord
One of the pair of folded, white membranes that have a free inner edge that oscillates as air passes through to produce sound.
Phonation
Production of speech sounds when air is pushed through the glottis and causes the vocal folds to vibrate.
Articulation
The part of speech in which air that flows from the lungs is shaped by the articulators in the mouth and nose.
summary
In this lesson, you learned about the structure and function of the larynx. Specifically, you explored the structure of the larynx and its roles in passing air through the respiratory tract and producing speech.
The part of speech in which air that flows from the lungs is shaped by the articulators in the mouth and nose.
Cricoid Cartilage
The portion of the larynx composed of a ring of cartilage with a wide posterior region and a thinner anterior region; attached to the esophagus.
Epiglottis
The leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing.
Glottis
The opening between the vocal folds through which air passes when producing speech.
Laryngeal Prominence
The region where the two lamine of the thyroid cartilage join, forming a protrusion known as the “Adam’s apple”.
Larynx
The cartilaginous structure that produces the voice, prevents food and beverages from entering the trachea, and regulates the volume of air that enters and leaves the lungs.
Phonation
Production of speech sounds when air is pushed through the glottis and causes the vocal folds to vibrate.
Thyroid Cartilage
The largest piece of cartilage that makes up the larynx and consists of two lamine.
True Vocal Cord
One of the pair of folded, white membranes that have a free inner edge that oscillates as air passes through to produce sound.
Vestibular Fold
The part of the folded region of the glottis composed of mucous membrane; supports the epiglottis during swallowing.
