What is the function of the vocal cords in a typical adult patient?

Function of the Vocal Cords

The vocal cords serve three essential physiological functions: voice production through vibration, airway protection during swallowing, and respiratory control through regulation of airflow.

Primary Functions

Voice Production (Phonation)

• Normal voice is created when two mobile vocal folds make contact in the midline space of the larynx (glottis), creating vibratory sound waves that are perceived as voice 1.
• The vocal folds form the oscillator of the vocal tract, working in coordination with the subglottic vocal tract (power source) and supraglottic vocal tract (resonator) 2.
• Voice production depends on intact and functional vocal fold mucosal and submucosal layers that allow proper vibratory patterns 1.
• The depth and quality of voice are influenced by vocal fold closure, with incomplete closure resulting in weak, breathy vocal quality and problems with pitch variation 1.

Airway Protection

• The vocal cords protect the lower airway through a hyperfunctional laryngeal reflex that prevents aspiration during swallowing 3.
• Proper vocal fold function provides airway protection during swallow, with glottic insufficiency resulting in reduced airway protection and increased aspiration risk 1.
• The vocal cords can paradoxically adduct (close) during inhalation as a protective reflex in response to irritants, post-nasal drip, or gastroesophageal reflux 3.

Respiratory Function

• The vocal cords regulate airflow during breathing by opening during inspiration and partially closing during expiration 3.
• Glottic insufficiency due to vocal fold weakness results in poor cough effectiveness, compromising the ability to clear secretions 1.

Clinical Implications of Dysfunction

Impact on Voice Quality

• Cancers that deeply invade the vocal cord or involve the anterior commissure result in glottic incompetency, poor vocal quality, and risk of aspiration 1.
• Defects in vocal fold closure result in weak, breathy hoarseness with vocal fatigue 1.

Impact on Swallowing and Airway Protection

• Vocal fold dysfunction increases aspiration risk, with studies reporting aspiration rates between 47% and 84% among symptomatic patients after radiation or chemoradiation therapy 1.
• Up to 50% of survivors of advanced head and neck cancer have dysphagia related to impaired vocal fold function 1.

Assessment Requirements

• All patients undergoing laryngeal treatment should undergo comprehensive assessment of voice and swallowing function to establish baseline status and guide treatment selection 1.
• The goal of functional evaluation is to establish baseline airway, speech, and swallowing status to minimize post-treatment dysfunction and optimize quality of life 1.

Common Clinical Pitfall

The most critical error is failing to recognize that vocal cord function extends beyond voice production alone—impaired vocal fold function simultaneously compromises airway protection, cough effectiveness, and swallowing safety, all of which significantly impact morbidity and quality of life 1.