Intrinsic muscles 00-13-49

Intrinsic muscles 00-13-49 - Home Vocal Topics Why Study...

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The Larynx: Structure and Function (Page 2 of 3) Intrinsic Muscles of the Larynx The muscles of the larynx consist mainly of muscles that change the opening of the glottis , as well as the tenseness of the vocal folds, thereby keeping the glottis open during respiration or more closed during vocalization. The extrinsic muscles connect the thyroid, cricoid, and arytenoid cartilages to other structures of the head and neck, while the smaller muscles within the structure of the larynx, the intrinsic muscles , move the vocal folds in reference to each other. The intrinsic muscles of the larynx abduct (move apart), adduct (bring together), alter vocal fold shape or change the longitudinal tension of the folds. The cricothyroid muscle lengthens and stretches the vocal folds. It lies anterior and external to the larynx, and is part of the muscular triangle of the neck . It arises from the cricoid cartilage and attaches to the inferior horn and lower margin of the thyroid cartilage . When it contracts, it pulls the thyroid cartilage forward around the axis through the cricothyroid joint , increasing the distance between the thyroid and arytenoid cartilages and stretching and tensing the vocal fold. (The action of the cricothyroid tilts the thyroid cartilage down, increasing the front- to-back distance of the larynx, and thus placing the vocal folds under increased tension. This action is often referred to as the ' laryngeal tilt ' or ‘rocking/pivoting the larynx’, and is important in being able to sing higher pitches.) Unlike all the other muscles of the larynx, which are innervated by the recurrent laryngeal nerve (branch) of the vagus , the cricothyroid muscle is the only muscle that is supplied by the external laryngeal branch of the vagus (superior laryngeal nerve). The cricothyroid ligament is the larger part of the laryngeal membrane, continuing inferiorly as a median or anterior part and twin lateral ligaments. The median cricothyroid ligament is a flat band of white tissue joining the cricoid and thyroid cartilages, while the lateral cricothyroid ligament (also known as the cricothyroid membrane ) keeps the cricoid and thyroid from traveling too far. The lateral cricoarytenoid muscle arises from the upper border of the cricoid cartilage and inserts into the muscular process of the arytenoid cartilages . The lateral cricoarytenoid muscles adduct and internally rotate the arytenoid cartilages to close the rima glottides (glottis). The posterior cricoarytenoid muscles arise from the expanse of the cricoid lamina and insert into the muscular process of the arytenoid cartilages. These muscles adduct and externally or laterally rotate the arytenoid cartilages, causing the vocal folds to separate from one another, thus opening the rima glottidis. These are the only muscles that are capable of opening the space between (abducting) the vocal folds to allow for normal breathing. If this muscle is incapacitated on both sides, as in a bilateral injury to
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This note was uploaded on 11/13/2010 for the course CODS 361 taught by Professor Gel during the Spring '10 term at WPUNJ.

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Intrinsic muscles 00-13-49 - Home Vocal Topics Why Study...

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