The epiglottis is a small, flexible structure in the throat that separates the respiratory and digestive systems. This flap of tissue acts like a switch, ensuring that the air we breathe travels into the lungs while food and liquids are directed toward the stomach. Without its precise and rapid movement, the simple acts of eating, drinking, and breathing would be impossible to coordinate safely.
Defining the Epiglottis: Structure and Placement
The epiglottis is formed primarily of elastic cartilage, a firm but highly flexible connective tissue that allows it to move freely and snap back into place after movement. This cartilage is covered by a specialized mucous membrane and is characterized by its distinctive leaf-like or teardrop shape. The structure is situated at the top of the larynx (voice box), which serves as the gateway to the trachea (windpipe).
The flap rests upright in the pharynx, projecting upward behind the tongue and slightly in front of the upper opening of the trachea. Its narrow lower portion is anchored to the inner surface of the thyroid cartilage, which forms the main structure of the larynx. A separate connective tissue band, the hyoepiglottic ligament, connects the front surface of the epiglottis to the hyoid bone, located high in the neck. This placement allows the epiglottis to remain open during breathing but enables its rapid, hinged movement during swallowing.
The Epiglottis’s Role in Swallowing and Breathing
The primary function of the epiglottis is to serve as a mechanical barrier during swallowing, ensuring that food enters the esophagus instead of the trachea. When a person is breathing, the epiglottis remains in its upward position, leaving the laryngeal inlet uncovered for the free passage of air.
This open position is necessary for respiration to occur without obstruction. The act of swallowing triggers a complex, involuntary reflex that coordinates the movement of several structures in the throat. As food or liquid is pushed back by the tongue, the entire larynx structure is pulled upward and forward toward the base of the tongue.
This upward movement causes the free, upper edge of the epiglottis to fold down over the glottis, which is the space between the vocal folds and the narrowest part of the airway. The epiglottis functions much like a hinged trapdoor, completely sealing off the entrance to the trachea.
Simultaneously, the food or liquid is guided by surrounding structures, such as the pharynx wall, to slide past the closed epiglottis and into the esophagus, which lies behind the trachea. After the swallowed material has safely passed, the larynx lowers, and the epiglottis springs back to its upright, resting position, reopening the airway for continuous breathing. Failure of this precise, reflexive coordination, often caused by talking or laughing while eating, results in the sensation of food or liquid “going down the wrong pipe,” triggering a strong coughing reflex.
Understanding Epiglottitis: Causes and Urgency
Epiglottitis is a serious medical condition characterized by the inflammation and swelling of the epiglottis and surrounding tissues. Because the epiglottis forms a lid over the airway, significant swelling can quickly narrow the passage for air. Historically, the condition was most commonly caused by a bacterial infection, specifically Haemophilus influenzae type b (Hib).
The widespread introduction of the Hib vaccine has dramatically reduced the incidence of epiglottitis in children, though it can still be caused by other bacteria like Streptococcus pneumoniae or Streptococcus pyogenes. Non-infectious causes, such as a direct injury to the throat, chemical burns from swallowing caustic substances, or thermal injury from inhaling very hot steam, can also lead to the acute swelling of the flap.
Symptoms often develop rapidly, especially in children, and may include a severe sore throat, difficulty and pain when swallowing, and a muffled or “hot potato” voice. As the swelling progresses, breathing becomes increasingly difficult, often accompanied by stridor, a high-pitched, harsh sound heard when inhaling. Drooling and leaning forward to maximize air entry are also common signs. Epiglottitis is a life-threatening medical emergency requiring immediate hospital attention to secure the breathing passage due to the potential for complete airway obstruction.