Learning objective

By the end of this lesson, the learner should be able to describe the ligaments and folds of the larynx, differentiate between intrinsic and extrinsic ligaments, and explain their role in airway protection, phonation, and clinical procedures such as cricothyroidotomy.

Overview of the larynx

The larynx (voice box) is an organ located in the anterior neck and is part of the respiratory tract. It performs several important functions, including phonation, the cough reflex, and protection of the lower respiratory tract.

The larynx contains numerous ligaments and folds. The ligaments support the cartilaginous skeleton, while the folds are essential for airway protection and voice production.

In this lesson, we will examine the anatomy of the laryngeal ligaments and folds, highlighting their structure, function, and clinical relevance.

Membranes and ligaments

The laryngeal membranes and ligaments provide support to the cartilaginous skeleton of the larynx.

Extrinsic ligaments attach the larynx to surrounding structures (e.g., hyoid bone and trachea).
Intrinsic ligaments hold the cartilages together internally, forming a functional laryngeal unit.

Extrinsic ligaments

Thyrohyoid membrane – spans between the superior thyroid cartilage and hyoid bone; pierced laterally by the superior laryngeal vessels and internal laryngeal nerve.
Median thyrohyoid ligament – anteromedial thickening of the thyrohyoid membrane.
Lateral thyrohyoid ligaments – posterolateral thickenings of the membrane.
Hyo-epiglottic ligament – connects the hyoid bone to the anterior aspect of the epiglottis.
Cricotracheal ligament – connects the cricoid cartilage to the trachea.
Median cricothyroid ligament – anteromedial thickening connecting the thyroid and cricoid cartilages.

Intrinsic ligaments

Cricothyroid ligament – originates from the cricoid cartilage and extends superiorly; its free upper edge forms the vocal ligament. It attaches anteriorly to the thyroid cartilage and posteriorly to the arytenoid cartilage.
Quadrangular membrane – spans between the anterolateral arytenoid cartilage and the lateral epiglottis. Its lower margin thickens to form the vestibular ligament, while the upper margin is free.

Clinical relevance – cricothyroidotomy

A cricothyroidotomy is an emergency procedure performed to secure a temporary airway when obstruction occurs at or above the larynx (e.g., foreign body, angioedema, or facial trauma) and intubation fails.

The thyroid cartilage is palpated in the neck.
A midline incision is made through the cricothyroid ligament.
An endotracheal tube is inserted to secure the airway.

Laryngeal folds

The larynx contains two important soft tissue folds: the vocal folds (true vocal cords) and the vestibular folds (false vocal cords). They are crucial for airway protection, phonation, and breathing.

Vocal folds

The vocal folds are the primary folds responsible for voice production. Muscles of phonation control their abduction, adduction, tension, and relaxation, modulating sound pitch.

Histological layers (superficial to deep):

Non-keratinized stratified squamous epithelium – protects against mechanical stress and foreign bodies.
Reinke’s space – a fluid-rich layer allowing free vibration of the epithelium.
Vocal ligament – the free upper edge of the cricothyroid ligament.
Vocalis muscle – fine muscle fibers lateral to the vocal ligament.

The space between the vocal folds is the rima glottidis.

Vocal folds are relatively avascular and appear white.

Vestibular folds

The vestibular folds lie superior to the vocal folds.
They consist of the vestibular ligament (lower edge of the quadrangular membrane) covered by mucosa.
They are fixed folds that protect the laryngeal inlet.
They appear pink in color, in contrast to the white vocal folds.