A coordinated system of paired arytenoid cartilages pivoting on the cricoid ring, five intrinsic laryngeal muscles that pull them, and motor signals carried by the recurrent and superior laryngeal nerves governs how the vocal cords open and close. The posterior cricoarytenoid muscle is the only opener, while the lateral cricoarytenoid, transverse arytenoid, and thyroarytenoid muscles bring the cords together for phonation, swallowing, and coughing.
This guide explains the anatomy, muscles, cartilage mechanics, and nerve pathways that govern vocal cord movement for students of voice, speech, and airway function.
The Anatomy of the Vocal Cords and the Larynx
Two slim bands of smooth muscle and mucosal tissue sit inside the larynx, the airway’s upper chamber. The bands stretch horizontally across the larynx, anchored at the front to the thyroid cartilage and at the back to a pair of small, pyramid-shaped arytenoid cartilages. The space between them is the glottis, and its shape shifts constantly as you breathe, speak, and swallow.
Where the cords sit and what they look like
Picture a small triangular window inside the throat. During quiet breathing, that window is wide open, and air moves through it without resistance. The cords themselves are thin, pearly-white strips roughly 17 to 21 millimeters long in adult women and 21 to 25 millimeters in adult men, per measurement standards referenced by the National Institute on Deafness and Other Communication Disorders.
Their mucosal covering vibrates when air passes between them at the right pressure, producing the sound that becomes the voice.
Why precise placement matters
Every breath and every word depends on this geometry. Open the cords a little and you whisper. Open them wide and air rushes through silently. Bring their edges close together under the right pressure, and the exhaled airstream sets them vibrating, generating pitch and tone.
The difference between a clear voice and a hoarse one often comes down to whether those edges meet evenly, which is why clinicians trained through the American Speech-Language-Hearing Association focus so heavily on cord closure during evaluation.
The Three States Vocal Cords Move Between
The same pair of tissues shifts between three distinct positions throughout the day. Knowing those positions clarifies why the larynx behaves differently across talking, swallowing, and breathing.
Open for breathing
During quiet inhalation and exhalation, the cords separate widely, forming a triangular gap that lets air move with no resistance. This is the resting position, maintained unconsciously by the brainstem with every breath cycle.
Nearly closed for phonation
For speaking and singing, the cords come close together along their length. Air pushed from the lungs builds pressure beneath them, and the escaping airstream sets the mucosal edges vibrating. The frequency of that vibration sets pitch, while the shape of the vocal tract shapes resonance.
Tightly sealed for protection
During swallowing and coughing, the cords slam shut. This reflex seals the airway from food, liquid, and debris, and it builds the pressure needed to clear the lungs forcefully during a cough. Damage to the nerves controlling this closure is one reason voice and swallowing problems so often appear together.
The Muscles That Open and Close the Vocal Cords
Five paired intrinsic laryngeal muscles do the work, and each changes cord position in a specific way. Together they manage abduction, adduction, and tension adjustments for pitch.
The single opener
The posterior cricoarytenoid muscle is the only muscle in the larynx that opens the cords. It rotates the arytenoid cartilages outward and backward, widening the back portion of the glottis. When this muscle fails on both sides, the cords cannot open fully, and breathing becomes a serious medical issue.
The closers and fine-tuners
Three muscles bring the cords back together. The lateral cricoarytenoid muscle rotates the arytenoids inward, closing the front portion of the glottis. The transverse arytenoid muscle pulls the two arytenoids toward each other, sealing the back. The thyroarytenoid muscle adjusts tension along the body of each cord, shaping closure during phonation so the edges meet evenly.
| Muscle | Primary Action | Cord Position Result |
|---|---|---|
| Posterior cricoarytenoid | Rotates arytenoids outward | Abduction (opening) |
| Lateral cricoarytenoid | Rotates arytenoids inward | Adduction (closing, front) |
| Transverse arytenoid | Pulls arytenoids together | Adduction (closing, back) |
| Thyroarytenoid | Shortens and thickens cords | Fine-tunes closure for pitch |
| Cricothyroid | Tilts thyroid cartilage forward | Lengthens cords, raises pitch |
How Arytenoid Cartilage Rotation Drives Movement
Because every cord movement depends on these small arytenoid cartilages, the way they pivot and glide matters more than the cords themselves. Think of the arytenoids as a pair of swiveling joints resting on top of the cricoid cartilage, which forms a complete ring at the base of the larynx.
Outward rotation opens the airway
When the posterior cricoarytenoid muscle contracts, it pulls the muscular process of each arytenoid backward. The arytenoid rotates so its vocal process swings outward, opening the posterior glottis, the widest part of the breathing channel. A small sliding motion along the cricoid accompanies the rotation, expanding the gap further.
Inward rotation closes the airway
The opposite rotation, driven by the lateral cricoarytenoid and transverse arytenoid muscles, swings the vocal processes toward the midline. The cord edges meet at the back first, then along their length, sealing the airway. Coordinated sliding and tilting during speech adjusts both the shape and the length of the opening, which is why trained singers shape vowels without losing phonation.
The Nerves and Brain Centers in Control
Every cord movement follows an electrical command, and that command travels through two main nerves with origins deep in the brainstem. Without these signals, the muscles cannot coordinate, and voice and airway protection collapse.
The recurrent laryngeal nerve
Every intrinsic laryngeal muscle except the cricothyroid receives its motor signals from a nerve that travels on an unusually long detour through the chest. Its name comes from its unusual path: it branches from the vagus nerve, loops around major vessels in the chest, and travels back up to the larynx. Because of that long route, it can be injured during thyroid, heart, or spine surgery, and even mild compression can weaken the cords.
The superior laryngeal nerve
Sensation above the glottis and a single muscle that lengthens the cords for higher pitch fall under the branch of the nerve described here. Damage to this nerve often produces a voice that tires easily and a reduced upper range, problems that affect teachers, singers, and radio broadcasters.
Persistent hoarseness, breathy voice, or sudden pitch loss lasting more than two weeks warrants evaluation by an otolaryngologist, who can visualize the cords directly with laryngoscopy.
Brainstem reflexes and cortical override
Brainstem respiratory centers automatically trigger cord opening with each inhalation, keeping the airway clear without conscious thought. Cortical areas override those automatic patterns, which is how you hold your breath underwater, speak on cue, or sustain a long note while singing. The same override explains why laughter, crying, and panic briefly disrupt automatic breathing rhythm.
What Goes Wrong When Vocal Cords Stop Opening or Closing Properly
When the muscles, cartilages, or nerves described above fail, the cords cannot reach the positions required for clear voice and safe swallowing. The symptoms depend on which structure is affected.
Paralysis from nerve injury
Damage to the recurrent laryngeal nerve can leave one or both cords paralyzed. A single paralyzed cord usually drifts toward the midline, producing a hoarse, breathy voice and weak cough. Bilateral paralysis leaves both cords stuck near the midline, which severely restricts breathing and often requires surgical intervention.
Incomplete closure from muscle weakness
Vocal cord bowing happens when the cords fail to meet along their length, allowing air to escape during speech. Aging, muscle atrophy, and certain neurological conditions all contribute. Voice therapy and, in some cases, surgical injection laryngoplasty help the cords close more completely.
Surface changes that interfere with contact
Inflammation from infection, nodules from chronic overuse, or acid reflux can swell or roughen the cord surfaces, preventing clean contact. Symptoms include roughness, vocal fatigue, and pain with prolonged speaking. Most surface problems respond to behavioral changes, hydration, and treatment of the underlying cause, though persistent lesions sometimes require removal.
Stop ignoring hoarseness that lasts beyond two weeks. A short office-based laryngoscopy gives a clinician a clear view of the cords and often catches issues before they become permanent.
Bottom Line
The vocal cords open and close through a tuned partnership of cartilages, muscles, and nerves. The posterior cricoarytenoid opens them for breathing, the lateral cricoarytenoid and transverse arytenoid close them for speech and protection, and the recurrent laryngeal nerve carries every command. When any part of that system falters, voice and airway protection suffer together, which is why early evaluation by a qualified specialist matters.
FAQ
What causes the vocal cords to open or close?
That open and close because tiny arytenoid cartilages rotate on the cricoid cartilage, driven by five intrinsic laryngeal muscles and commanded by the recurrent and superior laryngeal nerves. Brainstem reflexes handle breathing automatically, while the cortex overrides those reflexes for speech and breath-holding.
Which muscles open and close the vocal cords?
The posterior cricoarytenoid muscle is the only opener. The lateral cricoarytenoid and transverse arytenoid muscles close them for phonation and airway protection, while the thyroarytenoid and cricothyroid adjust tension for pitch.
What nerve controls the vocal cords?
The recurrent laryngeal nerve controls every intrinsic laryngeal muscle except the cricothyroid, which is supplied by the superior laryngeal nerve. Both nerves branch from the vagus nerve.
How does the brain control vocal cord movement?
Brainstem respiratory centers send automatic signals that open the cords with each breath. Cortical regions override those signals when you speak, sing, or hold your breath, layering voluntary control on top of the automatic rhythm.
Why do vocal cords close during swallowing?
Airway sealing during swallowing depends on the cords pulling tightly together, keeping food and liquid out of the trachea and lungs. This adduction also generates the pressure needed for a productive cough if anything slips past.
What is the role of the larynx in vocal cord movement?
The larynx houses the cords, supports the arytenoid cartilages that pivot to move them, and protects the lower airway. Its cartilage framework gives the intrinsic muscles something stable to pull against, making precise opening and closing possible.
