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The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx and is the only muscle that can open the vocal cords. It originates from the cricoid cartilage and inserts onto the arytenoid cartilage. It is innervated by the recurrent laryngeal nerve and its branches. The posterior cricoarytenoid muscle plays a crucial role in respiration and speech by abducting the vocal folds and opening the rima glottidis, allowing for the passage of air during inspiration and expiration. Paralysis of this muscle can lead to asphyxia, making it vital for breathing. Treatments for conditions affecting the posterior cricoarytenoid muscle, such as Abductor Spasmodic Dysphonia, involve injecting Botox to improve voice quality and respiratory function.
| Characteristics | Values |
|---|---|
| Muscle Group | Intrinsic muscle of the larynx |
| Function | Opens the vocal cords, allowing breathing and speech |
| Artery Supply | Laryngeal branches of the superior and inferior thyroid arteries |
| Innervation | Recurrent laryngeal nerve |
| Treatment | Botox injections to improve voice quality |
| Failure | Usually due to damage to the recurrent laryngeal nerve |
| Symptoms of Failure | Hoarseness and reduced vocal stamina |
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What You'll Learn
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx
The posterior cricoarytenoid muscle is innervated by the recurrent laryngeal nerve, which is a branch of the vagus nerve. It receives arterial supply from the laryngeal branches of the superior and inferior thyroid arteries. The venous blood is drained into the superior and inferior laryngeal veins, which then empty into the internal jugular vein.
The posterior cricoarytenoid muscle is involved in the production of unvoiced vocal sounds. It does this by adjusting the length and tension of the vocal cords, thereby modulating the process of phonation. Contraction of the muscle rotates the arytenoid cartilages laterally and pulls them posterolaterally. This separates the vocal cords and assists the other intrinsic muscles in lengthening the vocal cords, allowing the passage of air during inspiration and expiration.
Paralysis of the posterior cricoarytenoid muscle can lead to asphyxia, as it is the only muscle that can open the vocal cords and, therefore, the glottis. A failure of this muscle's function is usually due to damage to the recurrent laryngeal nerve, often during thyroidectomy operations or due to diseases of the surrounding organs that compress or infiltrate the nerve. Treatment for this condition may include injecting the muscle with Botox to stop its activity and improve voice quality.
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It is the only muscle that can open the vocal cords
The posterior cricoarytenoid muscle is a bilaterally paired intrinsic muscle of the larynx. It is the only muscle that can open the vocal cords. By abducting the vocal folds, the muscle opens the rima glottidis, which is important for breathing and speech. The muscle is involved in the production of unvoiced vocal sounds.
The posterior cricoarytenoid muscle originates from the cricoid cartilage and inserts onto the arytenoid cartilage of the same side. It is innervated by the recurrent laryngeal nerve, receiving motor innervation from its anterior division. The muscle rotates the arytenoid cartilages laterally, pulling them posterolaterally and thereby abducting the vocal processes and the vocal folds attached to them. This action of abducting the vocal folds is unique to the posterior cricoarytenoid muscle.
The muscle fibres of the posterior cricoarytenoid vary in orientation. The superior-most fibres are horizontally oriented, the intermediate fibres are oblique, and the inferior-most fibres are vertically oriented. This variation in fibre orientation suggests that the muscle could produce different movements depending on which portion of the muscle contracts. The posterior cricoarytenoid muscle is also identified by its two distinct bellies, the medial belly and the lateral belly, which differ in the orientation of their muscle fibres.
The posterior cricoarytenoid muscle is an important muscle in respiration. As the only muscle that can open the glottis, paralysis or failure of this muscle can lead to asphyxiation and even death. A common cause of posterior cricoarytenoid muscle failure is damage to the recurrent laryngeal nerve, which may occur during thyroidectomy operations or due to diseases affecting surrounding organs.
The muscle is also involved in the treatment of Abductor Spasmodic Dysphonia, where it is injected with Botox to stop its activity and improve voice quality.
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It is supplied by the superior and inferior thyroid arteries
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx. It is the only muscle capable of opening the vocal cords and, as such, is considered the main respiratory muscle of the larynx. It is innervated by the recurrent laryngeal nerve and receives arterial supply from the laryngeal branches of the superior and inferior thyroid arteries.
The superior and inferior thyroid arteries are themselves branches of the external carotid and subclavian arteries, respectively. The venous blood from these arteries is drained into the superior and inferior laryngeal veins, which then empty into the internal jugular vein. This intricate network of blood vessels ensures a steady supply of oxygenated blood to the posterior cricoarytenoid muscle, supporting its vital role in respiration and vocal cord function.
The function of the posterior cricoarytenoid muscle is to abduct the vocal cords, or vocal folds, by rotating the arytenoid cartilages laterally. This action opens the rima glottidis, allowing for the passage of air during inspiration and expiration. This process is crucial for breathing and speech, and paralysis of this muscle can lead to asphyxia.
The muscle's unique ability to open the vocal cords also makes it an important target for medical interventions. For example, in the treatment of Abductor Spasmodic Dysphonia, the posterior cricoarytenoid muscle is identified by EMG recording and injected with Botox to improve voice quality. By selectively paralysing this muscle, doctors can alleviate symptoms and improve patients' quality of life.
In summary, the posterior cricoarytenoid muscle is a vital component of the larynx, and its blood supply from the superior and inferior thyroid arteries is essential for maintaining its function. Its role in abducting the vocal cords and opening the rima glottidis makes it critical for respiration and vocalisation, highlighting the importance of a healthy blood supply to this muscle.
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Paralysis of the muscle can lead to asphyxiation
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx. It is the only muscle that can open the vocal cords and is, therefore, a main respiratory muscle. The muscle arises from the cricoid cartilage and inserts onto the arytenoid cartilage of the same side. It is innervated by the recurrent laryngeal nerve, a branch of the vagus nerve.
The muscle's function is to rotate the arytenoid cartilages laterally, pulling them posterolaterally. This movement separates the vocal cords and assists other intrinsic muscles in lengthening the vocal cords, allowing the passage of air during inspiration and expiration. This makes the posterior cricoarytenoid muscle the most important muscle in the larynx for respiration.
Paralysis of the posterior cricoarytenoid muscle can lead to asphyxiation and death. As the only muscle that opens the glottis, paralysis of this muscle can cause a blockage of the airway. This is a life-threatening condition. Denervation of the muscle leads to a slow fibrosis that worsens over many months.
The failure of the posterior cricoarytenoid muscle is usually caused by damage to the recurrent laryngeal nerve. This injury often occurs during thyroidectomy operations or due to diseases of surrounding organs that compress or infiltrate the nerve, such as bronchial tumours or goitre of the thyroid gland. Bilateral palsy of the nerve causes paralysis of the posterior cricoarytenoid muscle. A diagnosis of nerve palsy is established through physical examination, laryngoscopy, and laryngeal electromyography.
Treatment for posterior cricoarytenoid muscle paralysis involves injecting Botox into the muscle to stop its activity and improve voice quality.
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It is involved in the treatment of Abductor Spasmodic Dysphonia
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx. It is the only muscle that abducts the vocal cords and opens the rima glottidis, making it essential for breathing and speech. The muscle is innervated by the recurrent laryngeal nerve, receiving motor innervation from its anterior division. It rotates the arytenoid cartilages laterally, pulling the vocal folds of the same side laterally and thus opening the vocal cords.
Abductor spasmodic dysphonia (ABSD) is a rare form of spasmodic dysphonia, a neurogenic disorder characterised by abrupt spasms of intrinsic laryngeal muscles. ABSD specifically results from involuntary contractions of the posterior cricoarytenoid muscle, leading to breathy breaks following voiceless consonants. Treatment of ABSD is challenging as botulinum toxin injections, the typical treatment method, have a shorter efficacy duration and only improve symptoms in about 70% of patients.
The posterior cricoarytenoid muscle is identified by EMG recording, and botulinum toxin injections are administered to stop its activity and improve voice quality. Unilateral injections are initially performed to avoid side effects such as stridor and airway obstruction. If there is no improvement in voice quality after two weeks, the opposite muscle is injected with an additional dose of botulinum toxin.
In some cases, surgical techniques are explored, such as unilateral type 1 thyroplasty, bilateral medialization laryngoplasty, and endoscopic partial posterior cricoarytenoid myectomy. For example, a 50-year-old male with ABSD underwent a bilateral PCA myoneurectomy after failing Botox therapy, and reported improved quality of life and satisfaction with his voice.
In summary, the posterior cricoarytenoid muscle is involved in the treatment of Abductor Spasmodic Dysphonia through targeted botulinum toxin injections and, in some cases, surgical procedures. The muscle's role in abducting the vocal cords and its impact on phonation make it a critical target for treating ABSD.
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Frequently asked questions
The posterior cricoarytenoid muscle is an intrinsic muscle of the larynx. It is the only muscle that can open the vocal cords.
The posterior cricoarytenoid muscle abducts the vocal cords and opens the rima glottidis. It also adjusts the length and tension of the vocal cords, allowing for the production of sound.
By opening the rima glottidis, the posterior cricoarytenoid muscle facilitates breathing and speech. It is considered the most important muscle in the larynx for respiration.
Paralysis of the posterior cricoarytenoid muscle can lead to asphyxia and potentially death, as it is the only muscle that can open the glottis.
In Abductor Spasmodic Dysphonia, the posterior cricoarytenoid muscle is identified by EMG recording and injected with Botox to improve voice quality.
