The cricoarytenoid muscles are small structures located within the larynx, commonly known as the voice box. These muscles control the movement of the arytenoid cartilages, which are involved in sound production. Their coordinated actions contribute to various fundamental bodily processes.
Anatomy and Location
The cricoarytenoid muscles are located in the larynx, at the top of the trachea. They attach to the cricoid cartilage, which forms the base of the larynx, and the arytenoid cartilages, located on the posterior cricoid. There are two pairs: the posterior cricoarytenoid muscles and the lateral cricoarytenoid muscles.
The posterior cricoarytenoid muscles are on the back surface of the cricoid cartilage. Their fibers attach to the muscular process of the arytenoid cartilages. The lateral cricoarytenoid muscles originate from the lateral cricoid cartilage and insert into the muscular process of the arytenoid cartilages. These attachments allow them to manipulate the arytenoids, influencing the vocal folds.
Primary Functions
The cricoarytenoid muscles control the position of the vocal folds by moving the arytenoid cartilages. The posterior cricoarytenoid muscle is the only laryngeal muscle that abducts, or opens, the vocal folds. When this muscle contracts, it rotates the arytenoid cartilages laterally, separating the vocal folds. This action widens the glottis, the space between the vocal folds, allowing for the passage of air.
Conversely, the lateral cricoarytenoid muscle adducts, or closes, the vocal folds. Its contraction rotates the arytenoid cartilages medially, bringing the vocal folds together. This movement narrows or closes the glottis, which is necessary for functions like voice production.
Impact on Voice and Breathing
The precise actions of the cricoarytenoid muscles are fundamental for both voice production and respiration. During inhalation, the posterior cricoarytenoid muscles contract to abduct the vocal folds, creating an open airway for air to enter the lungs. This widening of the glottis ensures unobstructed airflow, which is particularly important during increased respiratory demands. The continuous opening and closing of the vocal folds are regulated by these muscles to facilitate the breathing cycle.
In terms of voice production, the lateral cricoarytenoid muscles play a significant role by adducting the vocal folds. When these muscles bring the vocal folds closer together, air pressure from the lungs causes them to vibrate, producing sound. The degree of adduction and tension, influenced by these and other laryngeal muscles, affects the pitch and quality of the voice. Their coordinated action with other laryngeal muscles allows for the complex range of sounds in speech and singing.
Common Problems and Their Manifestations
Dysfunction of the cricoarytenoid muscles can lead to difficulties in both voice and breathing. If the posterior cricoarytenoid muscle is impaired, such as through paralysis, the vocal folds may not fully abduct, leading to a narrowed airway. This can result in symptoms like difficulty breathing, noisy breathing sounds (stridor), and increased physical exhaustion, especially during activity. In severe cases, bilateral paralysis can significantly restrict airflow.
Problems affecting the lateral cricoarytenoid muscle, or its nerve supply, can manifest as voice disorders. When this muscle’s function is compromised, the vocal folds may not adduct properly, impacting their ability to vibrate effectively. This can lead to changes in voice quality, such as hoarseness, reduced vocal stamina, or a weakened voice. These manifestations highlight the intricate connection between muscle function and clear vocalization.