What is laryngeal spasm reflex

The laryngeal spasm reflex, also known as the laryngospasm reflex, is an involuntary protective mechanism that causes a sudden, forceful closure of the vocal cords. This reflex prevents foreign material, such as food, liquid, or vomit, from entering the trachea and lungs. It is a critical defense against aspiration.

When irritants or foreign bodies stimulate the sensitive laryngeal mucosa, sensory nerves send signals to the brainstem. The brainstem then triggers motor signals that cause the laryngeal muscles to contract, leading to the closure of the glottis (the space between the vocal cords). This closure momentarily stops breathing and can cause a characteristic "crowing" sound when breathing resumes.