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 In humans, vocal cords, also known as vocal folds or voice reeds, are folds of throat tissues that are key in creating sounds through vocalization. The size of vocal cords affects the pitch of voice. Open when breathing and vibrating for speec ...

Structure

The cricothyroid muscle originates from the anterolateral aspect of the cricoid cartilage, and inserts to the inferior cornu and lower

lamina Lamina may refer to: Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathematics * Laminar flow, (or streamline flow) occurs when a fluid flows in parallel layers, with no disruption betwee ...

of the thyroid cartilage.

Innervation

This muscle is the only laryngeal muscle innervated by the superior laryngeal branch of the vagus nerve known as the

superior laryngeal nerve The superior laryngeal nerve is a branch of the vagus nerve. It arises from the middle of the inferior ganglion of vagus nerve and in its course receives a branch from the superior cervical ganglion of the sympathetic nervous system. The superi ...

Function

The cricothyroid muscle produces tension and elongation of the

. 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, and the folds are consequently elongated, 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

File:Gray560.png, The veins of the thyroid gland. File:Gray562.png, The fascia and middle thyroid veins. File:Gray957.png, Side view of the larynx, showing muscular attachments.

References