Larynx
Published: Jul 17, 2023
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Updated: Jul 28, 2023
Written by Oseh Mathias
Founder, SpeechFit
The larynx, commonly known as the voice box, is a structure located in the throat at the top of the windpipe (trachea) and just below the base of the tongue. It plays a crucial role in speech production and the protection of the airway during swallowing[1].
The primary functions of the larynx include:
Phonation: The larynx houses the vocal folds, also known as vocal cords, which are two bands of elastic tissue[2]. When air passes through the larynx, the vocal folds vibrate, producing sound waves[3]. These vibrations, along with adjustments in tension and position of the vocal folds, create different pitches and voice qualities that form the basis of human speech and singing[4].
Airway Protection: The larynx serves as a protective mechanism during swallowing. When we swallow, the larynx rises to close off the entrance to the trachea, preventing food and liquid from entering the airway and instead directing them to the esophagus. This prevents choking and ensures that food and liquids go down the right pathway for digestion[5].
Respiration: The larynx also has a role in regulating airflow during breathing. The vocal folds can adjust their position to control the size of the glottis (the opening between the vocal folds). This adjustment helps regulate the amount of air passing through the larynx during inhalation and exhalation[6].
Anatomically, the larynx is composed of several cartilages, muscles, and connective tissues that work together to achieve its functions[7].
Cartilages: The larynx contains several cartilages, which provide its structure.
Thyroid Cartilage: This is the largest cartilage of the larynx, often referred to as the "Adam's Apple." It is more prominent in men than in women due to differences in sexual development[9].
Cricoid Cartilage: This cartilage forms the base of the larynx and is located below the thyroid cartilage. It is shaped like a signet ring, with a larger part positioned posteriorly[10].
Epiglottis: This leaf-shaped cartilage is attached to the inner side of the thyroid cartilage and swings down to cover the larynx when swallowing to prevent food or drink from entering the airways[11].
Arytenoid Cartilages: These are a pair of small, pyramid-shaped cartilages that sit on top of the cricoid cartilage. They are critical for vocal cord movement[12].
Muscles: The muscles of the larynx are divided into extrinsic and intrinsic muscles. Extrinsic muscles are responsible for the elevation and depression of the larynx during swallowing and speech, while intrinsic muscles control the tension and position of the vocal cords, affecting voice modulation[13]. The muscles surrounding the larynx are responsible for controlling the position, tension, and movement of the vocal folds, enabling precise control over speech and voice production[14].
Glottis: This is the opening between the vocal cords. Its size is adjusted for voice modulation and breathing.
Vocal Cords (Vocal Folds): These are folds of mucous membrane that stretch across the interior of the larynx. They vibrate to produce sounds and speech[15].
Vestibular folds (False vocal cords): These are a pair of thick folds of mucous membrane each enclosing a narrow band of fibrous tissue, the vestibular ligament, that extends along the lateral wall of the larynx from the thyroid cartilage in front to the arytenoid cartilage in the back. They are not involved in voice production, but close off the larynx during swallowing and exertion.
Ventricles and Vestibule: These are spaces within the larynx. The laryngeal ventricle is a small midline recess located between the vestibular and vocal folds. The vestibule is the portion of the laryngeal cavity that extends from the laryngeal inlet to the vestibular folds[16].
Ligaments and Membranes: These include the cricothyroid ligament (between the cricoid and thyroid cartilages) and the thyrohyoid membrane (between the thyroid cartilage and the hyoid bone). These structures help maintain the position and structure of the laryngeal components[17].
Nerves: The main nerve supplying the larynx is the recurrent laryngeal nerve, a branch of the vagus nerve. It provides sensory innervation and motor control to the muscles of the larynx, except for the cricothyroid muscle, which is innervated by the external branch of the superior laryngeal nerve[18].
Blood Supply: The larynx is supplied with blood by branches from the superior and inferior thyroid arteries[19].
Oseh is a software engineer, entrepreneur and founder of SpeechFit. Oseh is passionate about improving health and wellbeing outcomes for neurodiverse people and healthcare providers alike.
References
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