Vocal Cords (True Vocal Folds)

1. Overview

The vocal cords, also known as the true vocal folds, are paired structures located within the larynx that are essential for phonation (voice production). They consist of mucosa-covered ligaments stretched horizontally across the laryngeal cavity. When air passes through the glottis (the space between the vocal folds), the folds vibrate, producing sound. The vocal cords also play vital roles in airway protection, cough reflex, and respiratory control.

2. Location

The true vocal folds are located:

• Inside the larynx, extending from the thyroid cartilage anteriorly to the arytenoid cartilages posteriorly

• Inferior to the vestibular folds (false vocal cords)

• Flanking the glottis, the space between the left and right vocal cords

They form the inferior boundary of the laryngeal ventricle, with each vocal fold contributing to the dynamic movements of the glottis during speech, breathing, and swallowing.

3. Structure

Each vocal fold is composed of multiple layered components:

• Epithelium: Stratified squamous non-keratinized epithelium, adapted for vibration and mechanical stress

• Lamina propria: Three layers:

  • Superficial layer: Loose, gelatinous tissue (Reinke’s space)

  • Intermediate layer: Elastic fibers

  • Deep layer: Collagenous fibers

• Vocal ligament: Formed by intermediate and deep lamina propria layers

• Vocalis muscle: The innermost component, part of the thyroarytenoid muscle, adjusts tension and mass of the fold

This unique multilayer structure allows for precise modulation of pitch, loudness, and tone.

4. Function

The primary functions of the true vocal cords include:

• Phonation: Vibrate as air passes through to create sound

• Pitch control: Tension is altered by intrinsic laryngeal muscles to change pitch

• Airway regulation: Open (abduct) during inhalation and close (adduct) during swallowing or phonation

• Protection: Prevent food, liquid, and foreign objects from entering the trachea

5. Physiological Role(s)

The vocal folds support multiple physiological functions beyond sound production:

• Speech and communication: Essential for articulated speech and vocalization

• Air pressure generation: Glottic closure helps build thoracoabdominal pressure during lifting, defecation, childbirth, etc. (Valsalva maneuver)

• Reflexive airway protection: Rapid closure in response to aspiration triggers the laryngeal cough reflex

• Respiratory modulation: Adjust glottic aperture to regulate airflow resistance during different respiratory phases

6. Clinical Significance

Vocal Cord Paralysis

Loss of motor function (usually due to injury of the recurrent laryngeal nerve) can result in:

• Unilateral paralysis: Hoarseness, weak voice, ineffective cough

• Bilateral paralysis: Airway obstruction, stridor, risk of respiratory failure

May result from surgery (e.g., thyroidectomy), tumors, or neurologic disease. Treatment includes voice therapy, vocal fold injection, or surgery (medialization thyroplasty).

Vocal Cord Nodules and Polyps

Benign lesions caused by chronic vocal abuse (e.g., singers, teachers). Symptoms include:

• Hoarseness

• Vocal fatigue

Treated with voice rest, speech therapy, and occasionally surgical excision.

Laryngitis

Inflammation of the vocal cords due to infection, overuse, or irritants (e.g., smoking, reflux). Leads to:

• Temporary hoarseness

• Loss of voice

Usually self-limiting; treatment involves rest and hydration.

Reinke’s Edema

Swelling of the superficial lamina propria (Reinke’s space) due to smoking or voice misuse. Results in:

• Deep, rough voice

• Airway narrowing in severe cases

May require surgical drainage if conservative treatment fails.

Laryngeal Cancer

Squamous cell carcinoma can arise from the true vocal folds. Early signs include persistent hoarseness. Because the vocal cords have limited lymphatic drainage, early cancers are often localized and highly treatable via radiation or surgery.

Intubation Injury

Prolonged or traumatic intubation can cause:

• Granulomas

• Posterior glottic stenosis

• Vocal fold scarring

May result in chronic dysphonia or airway compromise.