An Introduction to the Anatomy of the Thyroarytenoid Muscle

Matthew Reeve

Muscles are generally named after their points of origin and insertion. Hence thyroarytenoid originating from the thyroid cartilage and inserting into the arytenoids cartilage. Some Latin names are still in use, however, as well as different terminology that arises from anatomical descriptions and functional descriptions.

There are essentially three parts to the thyroarytenoid muscle.

Thyrovocalis: originates from the inner surface of the thyroid cartilage, just below the thyroid notch and inserts on the vocal process of the arytenoid cartilage. When this muscle contracts it opens the crico-thyroid visor. It can also tense the vocal folds when it acts in tandem as an antagonist with the cricothryroid muscle. This muscle is also known commonly as the vocalis or the medial part of the thyroarytenoid muscle.

Thyromuscularis: this part of the thyroarytenoid, known as the lateral section, inserts higher on the arytenoid cartilage on to the muscular process. It has the same function as the lateral cricoarytenoid the vocal folds with adduct and lengthen along the free edge. This muscle may also be called the muscularis or the lateral part of the thyroarytenoid muscle.

Thyroepiglottis: also known as the superior thyroarytenoid muscle. Some anatomists say this muscle is not present in all individuals. It originates higher on the internal surface of the thyroid cartilage and has a more oblique direction back down toward the muscular process of the arytenoid where it inserts. When present this muscle seems to serve as a relaxer of the vocal fold. It may also possibly be responsible for changing and controlling the internal dimensions of the epilarynx and false vocal folds.

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