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The larynx is a flexible structure that houses the vocal cords and is responsible for producing phonation. The muscles of the larynx can be divided into two groups: external muscles and internal muscles. The internal muscles, or intrinsic muscles, move the vocal cords to produce speech sounds. The intrinsic muscles of the larynx alter the length and tension of the vocal cords, as well as the rima glottidis. The posterior cricoarytenoid muscle is the only muscle that abducts the vocal cords, and it is, therefore, the main respiratory muscle of the larynx.
| Characteristics | Values |
|---|---|
| Muscle that abducts vocal cords | Posterior cricoarytenoid muscle |
| Location | Originates from the posterior surface of the cricoid cartilage |
| Attaches to the muscular process of the arytenoid cartilage | |
| Function | Abduction of the vocal folds |
| Widening the rima glottidis | |
| Opening the rima glottidis | |
| Opening the true vocal folds | |
| Externally rotates the arytenoid cartilages | |
| Assists in lengthening the vocal cords | |
| Enables passage of air during inspiration and expiration | |
| Innervation | Inferior laryngeal nerve (branch of recurrent laryngeal nerve) |
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What You'll Learn
- The posterior cricoarytenoid muscle is the only muscle that abducts the vocal cords
- The cricothyroid muscle lengthens and tenses the vocal cords
- The thyroarytenoid muscle relaxes the vocal cords
- The vocalis muscle selectively relaxes and tenses the vocal cords
- The lateral cricoarytenoid muscle adducts the vocal cords
The posterior cricoarytenoid muscle is the only muscle that abducts the vocal cords
The larynx houses the vocal cords and is responsible for phonation, airway protection, and regulating intrathoracic and intra-abdominal pressures. The muscles of the larynx can be divided into two groups: the external muscles and the internal muscles. The external muscles act to elevate or depress the larynx during swallowing, while the internal muscles, or intrinsic muscles, move the individual components of the larynx, playing a vital role in breathing and phonation.
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx. It is the only muscle of the larynx that abducts the vocal cords, or vocal folds, and is, therefore, the only muscle capable of widening the rima glottidis. The posterior cricoarytenoid muscle originates from the posterior surface of the cricoid cartilage and attaches to the muscular process of the arytenoid cartilage. The contraction of this muscle rotates the arytenoid cartilages laterally and pulls them posterolaterally, separating the vocal cords and assisting other intrinsic muscles in lengthening the vocal cords. This action allows for the passage of air during inspiration and expiration, making the posterior cricoarytenoid muscle the most important muscle in the larynx for respiration.
The abduction of the vocal cords by the posterior cricoarytenoid muscle is essential for normal breathing. If this muscle is incapacitated on both sides, the inability to abduct the vocal cords can lead to difficulty breathing. Paralysis of this muscle can even result in asphyxiation and death. The posterior cricoarytenoid muscle is also believed to participate in the production of unvoiced sounds, such as letters that do not require vibration of the vocal cords.
The posterior cricoarytenoid muscle is innervated by the recurrent laryngeal nerve, a branch of the vagus nerve. Injury to this nerve can result in a loss of function of the posterior cricoarytenoid muscle, leading to symptoms such as hoarseness and reduced vocal stamina.
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The cricothyroid muscle lengthens and tenses the vocal cords
The larynx houses the vocal cords and is responsible for producing phonation. The muscles of the larynx can be divided into two groups: external muscles and internal muscles. The external muscles act to elevate or depress the larynx during swallowing, while the internal muscles, or intrinsic muscles, move the individual components of the larynx, playing a vital role in breathing and phonation.
The intrinsic laryngeal muscles act on the individual components of the larynx, controlling the shape of the rima glottidis (the opening between the vocal folds and the arytenoid cartilages) and the length and tension of the vocal folds. The intrinsic muscles of the larynx (except the cricothyroid) are innervated by the inferior laryngeal nerve, a branch of the recurrent laryngeal nerve.
The cricothyroid muscle, also known as the 'singer's muscle', is innervated by the external branch of the superior laryngeal nerve, derived from the vagus nerve. It originates from the anterolateral aspect of the cricoid cartilage and attaches to the inferior margin and inferior horn of the thyroid cartilage. When the cricothyroid muscle contracts, it pulls the thyroid cartilage downward and anteriorly, causing rotation about the cricothyroid joint. This results in the stretching, lengthening, tightening, and thinning of the vocal folds, leading to higher-pitched sounds during vocalization.
The cricothyroid muscle is responsible for producing tension and elongation of the vocal cords. It achieves this by drawing up the arch of the cricoid cartilage and tilting back the upper border of the cricoid cartilage lamina. This action increases the distance between the vocal processes and the angle of the thyroid, elongating and tensing the vocal folds, resulting in higher pitch phonation. The cricothyroid muscle is unique in that it does not attach to the arytenoid cartilage like the other intrinsic muscles.
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The thyroarytenoid muscle relaxes the vocal cords
The larynx houses the vocal cords and is responsible for producing phonation. The muscles of the larynx can be divided into two groups: external muscles and internal muscles. The external muscles act to elevate or depress the larynx during swallowing, while the internal muscles, or intrinsic muscles, act to move the individual components of the larynx, playing a vital role in breathing and phonation.
The thyroarytenoid muscle is an intrinsic laryngeal muscle that originates from the angle of the thyroid cartilage and adjacent cricothyroid ligament. It inserts into the anterolateral surface of the arytenoid cartilage, just like the posterior and lateral cricoarytenoid muscles. The thyroarytenoid muscle is innervated by the recurrent laryngeal nerve, a branch of the vagus nerve. It receives a communicating branch from the external laryngeal nerve and is supplied by the laryngeal branches of the superior and inferior thyroid arteries.
The thyroarytenoid muscle is a broad, thin muscle that forms the body of the vocal fold and supports the wall of the ventricle and its appendix. It functions to shorten and relax the vocal cords by contracting and rotating the arytenoid cartilages inward. This muscle is also involved in producing speech, with its upper portion, known as the vocal muscle, primarily involved in this function. Some of the fibres of the thyroarytenoid muscle extend into the aryepiglottic fold and continue to the margin of the epiglottis, forming the thyroepiglotticus muscle.
The thyroarytenoid muscle, along with the cricothyroid and vocalis muscles, works as a group to regulate the length and tension of the vocal folds. This regulation helps control the pitch and register of the voice. The contraction of the thyroarytenoid muscle can further adduct the vocal folds, in addition to shortening them.
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The vocalis muscle selectively relaxes and tenses the vocal cords
The vocalis muscle is located immediately lateral to the vocal ligaments. It runs from the vocal process of the arytenoid cartilage to the ipsilateral vocal ligament. The vocalis muscle is one of the intrinsic muscles of the larynx, which move the vocal cords to produce speech sounds.
The vocalis muscle also has a role in tensing the vocal cords. This is achieved by tilting the thyroid cartilage and increasing the distance between the thyroid prominence and the arytenoid cartilages. The tension on the vocal cords results in a higher pitch of the produced sound.
The vocalis muscle, along with the other intrinsic muscles of the larynx, plays a vital role in breathing and phonation. The intrinsic muscles act on the individual components of the larynx, controlling the shape of the rima glottidis (the opening between the vocal folds and the arytenoid cartilages) and the length and tension of the vocal folds. The vocal folds, also known as the vocal cords, are medial projections of the laryngeal walls that can approximate at the midline, fully obstructing the laryngeal lumen.
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The lateral cricoarytenoid muscle adducts the vocal cords
The larynx houses the vocal cords and is essential for phonation, or the production of sound. The muscles of the larynx can be divided into two groups: the external muscles and the internal muscles. The external muscles act to elevate or depress the larynx during swallowing, while the internal muscles, or intrinsic muscles, move the individual components of the larynx and play a vital role in breathing and phonation.
The lateral cricoarytenoid muscle is one of the intrinsic muscles of the larynx. It functions in the adduction of the vocal folds, or vocal cords, by pulling the muscular processes anteriorly, rotating the arytenoid cartilages so that the vocal processes swing medially. The arytenoid cartilages are triangular pieces of cartilage located at the posterosuperior border of the cricoid cartilage. They are the most important of the paired cartilages because they influence the position and tension of the vocal cords. The lateral cricoarytenoid muscle is considered the principal adductor of the vocal folds.
The lateral cricoarytenoid muscle acts in opposition to the posterior cricoarytenoid muscle, which is the only muscle of the larynx capable of abducting the vocal folds and opening the rima glottidis. Contraction of the posterior cricoarytenoid muscle rotates the arytenoid cartilages laterally and pulls them posterolaterally, separating the vocal cords and assisting in lengthening them. This action is important for respiration, as it allows for the passage of air during inspiration and expiration. The posterior cricoarytenoid muscle is, therefore, the most important muscle in the larynx for the act of breathing.
The lateral cricoarytenoid muscle narrows the rima glottidis, which is the space between the vocal folds, and modulates the tone and volume of speech. It also acts to protect the airway by closing the glottis. The intrinsic muscles of the larynx work in opposite pairs to open and close, or lengthen and shorten the vocal folds. In addition to the adductor and abductor muscles, there are sphincter muscles, muscles that tense the vocal cords, and muscles that relax the vocal cords.
The lateral cricoarytenoid muscle extends from the cricoid cartilage to the muscular process of the arytenoid cartilage. The cricoid cartilage is a triangular-shaped structure that forms the lower border of the larynx. The intrinsic muscles of the larynx are innervated by the recurrent laryngeal nerve, a branch of the vagus nerve.
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Frequently asked questions
The posterior cricoarytenoid muscle is the only muscle that abducts the vocal cords.
The posterior cricoarytenoid muscle is a paired muscle that belongs to the group of intrinsic muscles of the larynx. It abducts and externally rotates the arytenoid cartilages, resulting in abducted vocal cords. This action opens the rima glottidis, allowing the passage of air during inspiration and expiration, making it the most important muscle in the larynx for respiration.
The posterior cricoarytenoid muscle originates from the posterior surface of the cricoid cartilage and attaches to the muscular process of the arytenoid cartilage.
A failure of the posterior cricoarytenoid muscle is usually due to damage to the recurrent laryngeal nerve, often occurring during thyroidectomy operations or due to diseases of surrounding organs that compress or infiltrate the nerve. Paralysis of this muscle can lead to asphyxiation and death.
