The cricothyroid ligament (also known as the cricothyroid membrane or cricovocal membrane) connects the thyroid cartilage with the cricoid cartilage below. It is composed of two parts:
- median cricothyroid ligament
- lateral cricothyroid ligament
The median cricothyroid ligament is the thickened part of the ligament in the midline. On either side of this are the lateral cricothyroid ligaments, known also as the conus elasticus, which is the thinner part of the structure which extends superiorly from the upper border of the cricoid cartilage to end in a free margin within the triangular space created by the thyroid lamina above.
These free margins are thickened to form the vocal ligaments which lie under the vocal folds to form the true ‘vocal cords’. The two upper free margins attach anteriorly to the inner surface of the thyroid cartilage in the midline, and posteriorly to the vocal processes of the arytenoid cartilages.
In an emergency situation where there is supraglottic airway obstruction (i.e. above the level of the vocal cords), the cricothyroid ligament can be cut to create a temporary airway.