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, thus increasing the pitch of the voice.
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 splits into two groups or parts. The oblique part travels posterolaterally and inserts onto the inferior cornu of the thyroid cartilage. The straight part travels posterosuperiorly and inserts onto the inferior margin of the lamina of the thyroid cartilage.
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.
Clinical significance
The cricothyroid muscles may be injected with botulinum toxin whilst treating spasmodic dysphonia.