Quadrangular Membrane, Superior View

Description

Viewed from superiorly into the laryngeal inlet, the quadrangular membrane (quadrangular lamina) spans from the lateral margin of the epiglottis anteriorly toward the arytenoid cartilages posteriorly, forming a broad sheet of submucosal connective tissue in the supraglottis. Its thickened superior free edge creates the aryepiglottic fold, running posterolaterally from the epiglottis to the arytenoid and corniculate cartilages, while the inferior free margin contributes to the vestibular ligament beneath the laryngeal mucosa. Medial to these folds lies the laryngeal vestibule, and deeper and more inferior the rima glottidis opens between the true vocal folds that converge toward the anterior commissure at the thyroid cartilage. Orientation matters. Functionally, this is the architecture that channels airflow and protects the airway during swallowing, and it is where supraglottic edema produces dramatic symptoms with modest tissue volume changes. Swelling along the aryepiglottic folds, as in thermal inhalation injury or angioedema, narrows the laryngeal inlet long before the glottis itself looks compromised on laryngoscopy, and the quadrangular membrane helps explain why that narrowing tracks along predictable lines of attachment. For surgeons and endoscopists, the relationship between the vestibular fold and the true vocal fold clarifies the corridor used in supraglottic laryngectomy and the landmarks assessed when staging supraglottic carcinoma. Use this superior view in head and neck anatomy teaching to distinguish vestibular from vocal folds and to introduce the aryepiglottic fold as a clinical airway landmark, or in ENT and anesthesia publications discussing fiberoptic laryngoscopy findings, supraglottitis, and airway obstruction patterns. It also supports patient-facing diagrams when explaining why supraglottic swelling can cause stridor despite mobile vocal cords. Anatomical accuracy verified by SciePro's Medical Advisory Board.