Dominic Stone
The glottis is the middle region of the voice box, or larynx, that contains the vocal cords, or vocal folds. The glottis is involved in breathing, speaking, and swallowing. The rima glottidis is the opening between the vocal cords, and it is opened by the contraction of the posterior cricoarytenoid muscles, which pull the arytenoid cartilages together. This action separates the vocal folds, allowing air to flow in and out of the lungs. When the vocal folds come together, the glottis closes.
| Characteristics | Values |
|---|---|
| Muscle that opens glottis | Posterior cricoarytenoid muscle |
| Muscle that closes glottis | Lateral cricoarytenoid muscle, interarytenoid muscle, and arytenoid muscle |
| Muscle that pulls the arytenoid cartilages together | Contraction of the interarytenoid muscle |
| Muscle that pulls the arytenoid cartilages apart | Contraction of the lateral cricoarytenoid muscle |
| Muscle that relaxes the vocal folds | Thyroarytenoid muscle |
| Muscle that adjusts tension in the vocal folds | Vocalis muscle |
| Muscle that tenses the vocal cords | Cricothyroid muscle |
| Muscle that forms the vocal folds | Thyroarytenoid muscle |
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What You'll Learn
- The posterior cricoarytenoid muscle opens the glottis
- The lateral cricoarytenoid and interarytenoid muscles close the glottis
- The intrinsic muscles of the larynx alter tension on the rima glottidis
- The adductor muscle group includes the lateral cricoarytenoid and transverse arytenoid muscles
- The abductors include the posterior cricoarytenoid muscle
The posterior cricoarytenoid muscle opens the glottis
The glottis is the middle region inside the larynx (or voice box) that contains the vocal cords (vocal folds). The rima glottidis is the opening between the vocal cords. The glottis helps us breathe and speak, and it also protects the lungs from contamination by the digestive tract.
The posterior cricoarytenoid muscle is the only muscle of the larynx that abducts the vocal cords and, therefore, opens the rima glottidis. It originates from the posterior surface of the lamina of the cricoid cartilage. The contraction of this muscle rotates the arytenoid cartilages laterally and pulls them posterolaterally, separating the vocal cords. This action assists the other intrinsic muscles in lengthening the vocal cords, allowing the passage of air during inspiration and expiration.
The posterior cricoarytenoid muscle is considered the most important muscle in the larynx in the act of respiration. It is also the only intrinsic muscle found external to the larynx itself. Owing to the fact that it is the only muscle that opens the glottis, paralysis of this muscle may lead to asphyxiation and death.
The posterior cricoarytenoid muscle is an antagonist to the lateral cricoarytenoid muscle, which acts to close the glottis and protect the airway. The lateral cricoarytenoid muscle rotates the arytenoids medially, bringing the vocal folds together. The interarytenoid muscle also functions to close the glottis by pulling the arytenoid cartilages together.
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The lateral cricoarytenoid and interarytenoid muscles close the glottis
The glottis is the middle region inside the larynx (or voice box) that contains the vocal cords. The rima glottidis is the opening between the two true vocal cords. The glottis is involved in breathing, speaking, and protecting the lungs from contamination by the digestive tract.
The rima glottidis changes shape during respiration and phonation due to the movement of the vocal cords and arytenoid cartilages. The glottis opens to allow air to flow into and out of the lungs. The contraction of glottal muscles is controlled by a specific pool of motoneurons located in the anterolateral n.
The lateral cricoarytenoid and interarytenoid muscles are the classical adductor muscles. They control the degree of glottis closure by rotating the arytenoid cartilages towards the midline. The lateral cricoarytenoid muscle arises from the lateral portion of the arch of the cricoid and inserts on the anterior surface of the muscular process of the arytenoids. Contraction of this muscle rotates the arytenoids medially, narrowing the rima glottidis and producing adduction of the vocal folds.
The interarytenoid muscle connects each arytenoid medial body to the other and assists in adducting the arytenoid cartilages. Contraction of this muscle pulls the arytenoid cartilages together in a gliding fashion, while relaxation allows these structures to move apart.
The lateral cricoarytenoid and interarytenoid muscles work in conjunction to close the glottis, with the lateral cricoarytenoid muscle rotating the arytenoids medially and the interarytenoid muscle pulling the arytenoid cartilages together.
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The intrinsic muscles of the larynx alter tension on the rima glottidis
The glottis is the middle region inside the larynx (or voice box) that contains the vocal cords. The rima glottidis is the opening between the two true vocal cords. The intrinsic muscles of the larynx alter tension on the rima glottidis by acting on the individual components of the larynx. They control the shape of the rima glottidis, as well as the length and tension of the vocal folds.
The intrinsic muscles of the larynx can be divided into adductors and abductors. The lateral cricoarytenoid muscles are the principal adductors. They pull the muscular processes anteriorly, rotating the arytenoid cartilages so that the vocal processes swing medially. The transverse and oblique arytenoid muscles are also adductors, pulling the arytenoid cartilages together to enable phonation. The lateral cricoarytenoid muscles also narrow the rima glottidis, modulating the tone and volume of speech.
The posterior cricoarytenoid muscles are the only abductors of the vocal folds, and the sole muscle capable of widening the rima glottidis. They pull the muscular processes posteriorly, rotating the vocal processes laterally. The cricothyroid muscles are also intrinsic muscles of the larynx that act as tensors, pulling the angle of the thyroid cartilage anteriorly and inferiorly toward the arch of the cricoid cartilage. This causes elongation and tightening of the vocal ligaments, resulting in a higher pitch of phonation.
The intrinsic muscles of the larynx also include relaxers, such as the thyroarytenoid muscles, which pull the arytenoid cartilages anteriorly, reducing the vocal ligaments and lowering the pitch of the voice. These muscles also shorten and relax the vocal cords. The vocalis muscles are another group of relaxers. The sphincter muscles include the transverse arytenoid, oblique arytenoid, and aryepiglottic muscles.
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The adductor muscle group includes the lateral cricoarytenoid and transverse arytenoid muscles
The glottis is the middle region inside the larynx (or voice box) that contains the vocal cords. The rima glottidis is the opening between the two vocal cords. The intrinsic laryngeal muscles act on the individual components of the larynx, controlling the shape of the rima glottidis, as well as the length and tension of the vocal folds.
The lateral cricoarytenoid muscles are the major adductors of the vocal folds. They narrow the rima glottidis, modulating the tone and volume of speech. The transverse and oblique arytenoid muscles adduct the arytenoid cartilages, closing the posterior portion of the rima glottidis and narrowing the laryngeal inlet.
The contraction of the lateral cricoarytenoid muscle, along with the interarytenoid muscle, produces inward rotation of the arytenoids, bringing the vocal processes together and narrowing the rima glottidis. This results in adduction of the vocal folds. The lateral cricoarytenoid muscle is, therefore, one of the classical adductor muscles involved in controlling the degree of glottis closure.
The glottis is protected from potential contamination of the airways with digestive tract material. However, aspiration can occur from the nasopharynx, oropharynx, or oesophagus, and in cases of glottic dysfunction, aspiration can lead to bacterial pneumonia, chemical pneumonitis, and pulmonary fibrosis.
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The abductors include the posterior cricoarytenoid muscle
The glottis is the middle region inside the larynx (or voice box) that contains the vocal cords (or vocal folds). The rima glottidis is the opening between the two true vocal cords. The glottis is part of the respiratory system and opens to allow air to flow into and out of the lungs.
The posterior cricoarytenoid muscle is the only muscle of the larynx that abducts the vocal cords and opens the rima glottidis. It is an intrinsic laryngeal muscle, controlled by the brain stem neuronal mechanism. It originates near the entire posterior midline of the cricoid cartilage and is innervated by the inferior laryngeal nerve. The posterior cricoarytenoid muscle is the main vocal cord abductor. It is also the only abductor muscle of the larynx.
Contraction of the posterior cricoarytenoid muscle rotates the arytenoid cartilages and moves the vocal folds laterally. 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. This action makes the posterior cricoarytenoid muscle the most important muscle in the larynx in the act of respiration. Owing to the fact that this is the only muscle that opens the glottis, paralysis of this muscle may lead to asphyxiation and death.
In some patients, weakening or paralyzing just one posterior cricoarytenoid muscle has produced significant voice improvement. However, in other patients, adverse effects have included exertional wheezing and dysphagia.
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Frequently asked questions
The glottis is the middle part of the voice box that contains the vocal cords.
The rima glottidis is the opening between the two true vocal cords.
The posterior cricoarytenoid muscle is the only muscle that opens the glottis. The lateral cricoarytenoid muscle and the interarytenoid muscles function to close the glottis.
