What event triggers the opening of the glottis during breathing?

The opening of the glottis during breathing is primarily influenced by the relaxation of the vocal cords. The glottis is the space between the vocal cords in the larynx, and its shape and size can be adjusted by the tension and position of these cords. When the vocal cords relax, the glottis opens wider, allowing air to flow more freely into the trachea and subsequently into the lungs during inhalation.

This process is vital for facilitating efficient ventilation. When the vocal cords are tense or closed, such as during phonation (speaking), the glottis narrows or closes entirely. Therefore, the relaxation of the vocal cords is a critical event that adjusts the glottal opening based on the state of the respiratory cycle, promoting normal airflow.

Other options, while related to breathing mechanics, do not directly trigger the opening of the glottis. For example, the contraction of the diaphragm primarily creates negative pressure in the thoracic cavity to facilitate inhalation but does not specifically cause the glottis to open. Increased thoracic pressure typically occurs during exhalation, contributing to airflow but not affecting the glottis directly in the context of the question. Decreased abdominal pressure relates to the diaphragm's actions and