The Purpose of the Epiglottis
The epiglottis serves as a protective structure that facilitates laryngeal closure during swallowing to prevent food and liquids from entering the trachea and lungs, though humans can adapt to its absence. 1
Primary Protective Function
The epiglottis plays a critical role in airway protection during the pharyngeal phase of swallowing through the following mechanisms:
The epiglottis contributes to laryngeal closure during deglutition, working as part of the coordinated protective events that include velopharyngeal closure and complete airway closure when the bolus is propelled from the oral cavity into the pharynx. 2
During normal swallowing, the epiglottis moves dynamically to help seal the laryngeal entrance, preventing aspiration of food and liquids of varying consistencies into the trachea. 1, 3
The epiglottis forms the anterior boundary of the vallecula, the anatomical space between the base of the tongue and the epiglottis where the bolus temporarily aggregates before the swallow is triggered. 4, 5
Clinical Evidence of Function
The importance of epiglottic function is demonstrated through pathological conditions:
Abnormal epiglottic mobility from calcification can cause dysphagia and aspiration problems by limiting the dynamic movement necessary for proper laryngeal protection during swallowing. 1, 3
Surgical procedures for intractable aspiration include suturing the epiglottis to the aryepiglottic folds (supracricoid partial laryngectomy), which demonstrates its role in airway protection, though 21.7% of patients still developed aspiration pneumonia post-operatively. 4
Important Clinical Caveat
Despite its protective role, the epiglottis is not essential for successful swallowing in humans. 6 This represents a critical clinical distinction:
Individuals can readily adapt to isolated epiglottectomy and avoid tracheal aspiration, as demonstrated in three adult patients who exhibited successful swallowing with all food types (thin liquid, puree, and solid food) following complete epiglottis removal. 6
The primary mechanism of airway protection during swallowing relies more heavily on complete laryngeal closure coordinated by sensory feedback from the internal superior laryngeal nerve (ISLN) rather than the physical presence of the epiglottis alone. 7
When ISLN function is impaired, laryngeal penetration occurs in 43% of swallows with 56% progressing to tracheal aspiration, indicating that sensory-mediated laryngeal closure is more critical than the epiglottis itself for preventing aspiration. 7
Practical Clinical Implications
In acute epiglottitis, the swollen epiglottis causes airway obstruction through mass effect rather than loss of protective function, presenting with odynophagia (100%), inability to swallow secretions (83%), and dyspnea (58%). 8
The epiglottis should be considered one component of a multi-level airway protection system that includes laryngeal sensation, vocal cord closure, and coordinated neuromuscular responses involving six cranial nerves. 2