cricothyroid muscle cricothyroid muscle the cricothyroid muscle is the only tensor muscle of the larynx aiding with phonation. it is innervated by the superior laryngeal nerve. its action tilts the thyroid forward to help tense the vocal cords. not to be confused with posterior cricoarytenoid muscle. cricothyroid musclemuscles of larynx. side view. right lamina of thyroid cartilage removed.the ligaments of the larynx. antero-lateral view.detailsoriginanterior and lateral cricoid cartilageinsertioninferior cornu and lamina of the thyroid cartilagenerveexternal branch of superior laryngeal nerve (branch of the vagus nerve)actionstension and elongation of the vocal foldsidentifierslatinmusculus cricothyroideusta98a06.2.08.001ta22193fma46417anatomical terms of muscle structure the cricothyroid muscle is a fan-shaped muscle situated at the outer surface of the larynx. origin the cricothyroid muscle originates from the anterolateral aspect of the cricoid cartilage. insertion the cricothyroid muscle inserts onto the inferior cornu of the thyroid cartilage and adjacent inferior margin of the lamina of thyroid cartilage. innervation the cricothyroid muscle is innervated by the external branch of the superior laryngeal nerve (a branch of the vagus nerve). it is the only laryngeal muscle innervated by this nerve. function the cricothyroid muscle produces tension and elongation of the vocal cords. they draw up the arch of the cricoid cartilage and tilt back the upper border of the cricoid cartilage lamina. the distance between the vocal processes and the angle of the thyroid is increased, elongating and thus tensing the vocal folds, thereby resulting in higher pitch phonation. they work as antagonists to the posterior cricoarytenoid muscles. clinical significance the cricothyroid muscles may be injected with botulinum toxin whilst treating spasmodic dysphonia. this is usually performed under guidance from electromyography. additional images the veins of the thyroid gland. the fascia and middle thyroid veins. side view of the larynx, showing muscular attachments.