COMEDK 2007 MCQ Answer 161

The correct answer is D

The Laryngeal Musculature:

The intrinsic muscles of the larynx, all of which are innervated by the recurrent laryngeal nerve, include:

1) Posterior cricoarytenoid - - the ONLY abductor of the vocal folds. Functions to open the glottis by rotary motion on the arytenoid cartilages. Also tenses cords during phonation.

2) Lateral cricoarytenoid - - functions to close glottis by rotating arytenoids medially.

3) Transverse arytenoid - - only unpaired muscle of the larynx. Functions to approximate bodies of arytenoids closing posterior aspect of glottis.

4) Oblique arytenoid - - this muscle plus action of transverse arytenoid function to close laryngeal introitus during swallowing.

5) Thyroarytenoid - - very broad muscle, usually divided into three parts:

• Thyroarytenoideus internus (vocalis) - adductor and major tensor of free edge of vocal fold.
• Thyroarytenoideus externus - major adductor of vocal fold
• Thyroepiglotticus - shortens vocal ligaments

The cricothyroid muscle is considered to be an extrinsic muscle of the larynx because it is innervated by the external branch of the superior laryngeal nerve. It functions to increase tension in the vocal folds, especially at the upper range of pitch or loudness.