The cartilages of the larynx are connected by several membranes. They include the thyrohyoid, cricothyroid and quarangular membranes.

Thyrohyoid membrane

The thyrohyoid membrane passes between the upper border of the thyroid cartilage and the upper border of the posterior surface of the hyoid bone. In the midline, it is thickened as the median thyrohyoid ligament. At the posterior edges are the lateral thyrohyoid ligaments, which extend from the superior horn of the thyroid cartilage to the tip of the greater horn of the hyoid bone. It is pierced by the superior laryngeal vessels and the internal laryngeal branch of the superior laryngeal nerve (branch of CN X).

Cricothyroid membrane

The elastic cricothyroid membrane (conus elasticus/cricovocal membrane) runs from the superior rim of the cricoid arch and vocal processes of the arytenoids to the inner surface of the thyroid angle. The most anterior fibres are thickened to form the median cricothyroid ligament. The superior edge of the cricothyroid membrane forms the vocal ligaments which are covered by overlying epithelium to form the vocal folds.

CLINICAL CORNER

If the airway is obstructed, emergency tracheostomy is performed by piercing the median cricothyroid ligament to gain access to the subglottic airway. Elective tracheostomy generally occurs between the second and third tracheal rings.

Quadrangular membrane

Each broad fibroelastic quadrangular membrane extends between the epiglottis and arytenoid cartilages. Its upper margin forms the aryepiglottic fold (in which run fibres of the aryepiglotticus), while its lower margin forms the vestibular fold (false cord).