The straight (anterior) part of cricothyroid produces the primary rocking movement of the thyroid cartilage over the cricoid ring, tensing and elongating the vocal folds. It acts in concert with the oblique part to produce the full range of pitch adjustment.
| Origin | Anterior lateral surface of the cricoid cartilage |
|---|---|
| Insertion | Lower border of the thyroid cartilage — anterior |
| Nerve Supply | External branch of the superior laryngeal nerve (CN X) |
| Blood Supply | Superior thyroid artery |
| Actions | Tenses the vocal folds by tilting the thyroid cartilage anteriorly over the cricoid; The straight part produces the primary tipping movement |
|---|
Cricothyroid muscle function is assessed pre and post-thyroidectomy using laryngoscopy with high-pitch phonation. Bilateral SLN injury after thyroid surgery is particularly disabling as no compensatory mechanism exists for cricothyroid. Voice therapy and surgical medialization address some of the resulting dysphonia.
Assessed by observing thyroid cartilage movement during high-pitch phonation and by laryngoscopy.
Bilateral external SLN injury in total thyroidectomy producing complete loss of high-pitch voice and chronic voice fatigue.
