Name the muscles of the larynx and their function.
Extrinsic muscles of the larynx divided into suprahyoids and infrahyoids.
Suprahyoids (above the hyoid) - elevate the larynx
1. Digastric (anterior and posterior bellies) – anterior draws the hyoid up and forward and posterior draws hyoid up and back.
2. Stylohyoid – pulls the hyoid bone posteriorly and upward.
3. Mylohyoid - elevates the hyoid or depresses the mandible.
4. Geniohyoid - elevates the hyoid bone and depresses the mandible.
Infrahyoids (below the hyoid) – depress the larynx. Use T.O.S.S. to remember.
1. Thyrohyoid - decreases the distance between the thyroid and hyoid, especially anteriorly.
2. Omohyoid (2 bellies because of shoulders) - pull down the hyoid bone.
- 3. Sternohyoid - pulls down the hyoid bone.
- 4. Sternothyroid - pulls the thyroid cartilage downward.
Function: Extrinsic muscles support the larynx and fix it in position. Primary function is to influence laryngeal height or tension as a gross unit. (Example: the larynx moves vertically as a whole in the neck for lifting, swallowing, phonating, and many vegetative tasks). Also it alters the shape & filtering characteristic of the supraglottic vocal tract, modifying vocal pitch, loudness, and quality.
Intrinsic muscles of the larynx (C.L.I.P.T.)
1. Cricothyroid - elongates and tenses the vocal folds. It decreases the space between the thyroid and cricoid. This increases the distance between the thyroid and arytenoids (PARS RECTA and PARS OBLIQUE).
2. Lateral Cricoarytenoid - adducts the vocal folds.
3. Interarytenoids - adduct the vocal folds (Transverse bundle - adducts the vocal folds and Oblique bundle - regulators of medial compression)
4. Posterior Cricoarytenoid - abduct the vocal folds.
5. Thyroarytenoid - adducts, tenses, relaxes the vocal folds (Vocalis muscle -tenses the vocal folds and Thyromuscularis - relaxes the vocal folds).
Function: Intrinsic muscles control sound and production. Primary function is to alter the shape and configuration of the glottis, by modifying the position and tension, and edge of the vocal folds.