The larynx, commonly called the voice box, serves as a critical gateway in your respiratory system. Sitting in the middle of your neck just above your windpipe, it does far more than produce sound. It actively controls airflow in and out of your lungs, protects your airways from food and liquid, and helps regulate pressure deep inside your chest. Every breath you take passes through this small, cartilage-framed tube.
Where the Larynx Sits in the Airway
Your larynx is a hollow tube positioned between the back of your throat (the pharynx above) and your trachea (the windpipe below). It connects the upper airway to the lower airway, making it the last checkpoint before air enters the lungs. The structure is built from a skeleton of cartilages: three large, unpaired pieces (the thyroid cartilage, cricoid cartilage, and epiglottis) and three smaller pairs (the arytenoids, corniculate, and cuneiform cartilages). The thyroid cartilage is the one you can feel at the front of your throat, sometimes called the Adam’s apple.
Inside this framework sit the vocal folds, two bands of tissue that can open and close to control the passage of air. The space between them is called the glottis, and its width changes constantly depending on whether you’re breathing, speaking, swallowing, or coughing.
Controlling Airflow During Breathing
During quiet breathing, the larynx adjusts the size of the glottic opening in a rhythm that matches your breath cycle. The opening widens during inhalation to let air flow freely into the lungs, and narrows slightly during exhalation. This narrowing isn’t accidental. By partially restricting outgoing air, the larynx creates a small amount of back-pressure that helps keep the tiny air sacs in your lungs (alveoli) from collapsing too quickly. This is especially important in people with lung conditions like COPD, where the vocal folds narrow more during exhalation to maintain airway pressure and improve airflow.
The timing is remarkably precise. During normal tidal breathing, the glottis begins widening about 160 milliseconds before air actually starts flowing in. Your brain is essentially pre-opening the airway in anticipation of each breath.
When you need to breathe harder, during exercise or when carbon dioxide levels rise, the pattern shifts. The degree of expiratory narrowing decreases so that air can move out more quickly. During a forced maximal exhalation, the glottis opens to its full inspiratory width. This is a coordinated effort: the brain simultaneously activates both the muscles that open the larynx and the muscles that push air out of the chest, minimizing resistance so the lungs can empty as efficiently as possible.
Only one pair of muscles in the larynx can pull the vocal folds apart. The posterior cricoarytenoid muscles open the glottis by pulling the back ends of the arytenoid cartilages together, which swings the front ends (where the vocal folds attach) apart. Without these muscles, the airway would not open properly for breathing.
Protecting the Lungs During Swallowing
Perhaps the larynx’s most vital respiratory role is keeping food and liquid out of the lungs. Every time you swallow, a rapid sequence of events seals off the airway. Your larynx and the hyoid bone (a small bone higher in the throat) move upward and forward. This motion pushes the base of your tongue against the epiglottis, a leaf-shaped flap of cartilage at the top of the larynx. Simultaneously, the muscles and ligaments attached to the epiglottis pull on it from below. The combined push-and-pull action flips the free end of the epiglottis backward, covering the laryngeal opening like a lid.
This happens with every single swallow. The epiglottis swings up and down each time, redirecting food and liquid toward the esophagus and away from the windpipe. Meanwhile, the vocal folds themselves clamp shut as a second line of defense. If anything does slip past the epiglottis, the closed vocal folds block it from reaching the trachea and lungs. When this system fails, food or liquid enters the airway, a dangerous situation called aspiration that can lead to choking or pneumonia.
Triggering the Cough Reflex
The lining of the larynx is packed with sensory nerve endings that act as an early warning system. These receptors fall into two main categories: rapidly adapting receptors (RARs) and C fiber receptors. Both types respond to mechanical and chemical irritants, but they have different strengths. The receptors in the larynx and trachea are especially sensitive to physical touch, such as a crumb of food contacting the airway wall, while receptors deeper in the bronchi respond more to chemical irritants like smoke or fumes.
The RARs are the primary triggers for coughing. When something touches or irritates the laryngeal lining, these receptors fire signals through the vagus nerve to the brainstem. The brain responds by orchestrating a cough: a deep inhale, closure of the vocal folds to build pressure, then a sudden explosive opening that blasts air outward at high speed to eject the irritant. This reflex is one of the body’s most important defenses against inhaling harmful substances.
Laryngospasm: When Protection Goes Too Far
The same protective reflexes that guard the airway can occasionally overreact. Laryngospasm is the sustained, involuntary closure of the vocal folds, resulting in partial or complete blockage of the airway. It is triggered by stimulation of the area around the glottis, with sensory signals traveling through the vagus nerve. The motor response involves the muscles that close and tighten the vocal folds clamping down and refusing to release.
Laryngospasm can be triggered by mechanical irritation (such as secretions or a foreign body near the vocal folds), chemical irritation, or even stimulation from elsewhere in the body through visceral nerve pathways. It is most commonly discussed in the context of anesthesia, where it can occur during lighter stages of sedation, but it can also happen during choking episodes or severe acid reflux. The result feels like suddenly being unable to breathe in, because the airway is physically locked shut.
How the Larynx Differs in Children
A child’s larynx is not simply a smaller version of an adult’s. In infants and young children, the larynx sits higher and more forward in the neck compared to its position in adults. At birth, the larynx is positioned high in the throat; it gradually descends to the middle of the neck by around age two. The shape also differs: a child’s larynx is conical (funnel-shaped), narrowing toward the bottom, while an adult’s is more cylindrical.
These differences matter because the narrower, higher airway in children means that even minor swelling from an infection like croup can significantly reduce airflow. The same amount of tissue inflammation that an adult would barely notice can cause noticeable breathing difficulty in a young child, which is why respiratory infections involving the larynx tend to be more serious in pediatric patients.