Where is the Rima Glottidis Located?
The rima glottidis is located within the laryngeal cavity (cavitas laryngis), specifically in its middle section, which corresponds to the level of the laryngeal ventricles. It lies directly inferior to the rima vestibuli (rima vestibuli) and vestibular folds (plicae vestibulares), and is bounded by the true vocal folds (plicae vocales).
What is the Anatomical Structure of the Rima Glottidis?
The structure of the rima glottidis (rima glottidis) comprises two main parts:
- Intermembranous part (pars intermembranacea) — located between the free margins of the vocal folds.
- Intercartilaginous part (pars intercartilaginea), which performs a respiratory function — located between the arytenoid cartilages.
The true vocal ligaments (ligg. vocalia), which form the lateral boundaries of the aperture, extend between the vocal processes (processus vocalis) of the arytenoid cartilages and the inner surface of the thyroid cartilage. The overlying mucosa, along with the vocalis muscle and the elastic cone (conus elasticus), forms the vocal folds. The interarytenoid notch (incisura interarytenoidea) is a vertical midline cleft located posteriorly that leads into the laryngeal vestibule.
What is the Role of the Rima Glottidis in Respiration and Sound Production?
As an anatomical narrowing of the respiratory tract, the rima glottidis creates conditions for high-velocity airflow. This generates turbulent sound waves that form physiological bronchial breath sounds (loud, harsh sounds heard during both inspiration and expiration). Normally, these sounds are auscultated over the trachea at the jugular notch and in the interscapular region at the level of the seventh cervical vertebra.
What is the Significance of the Rima Glottidis in the Cough Mechanism?
The rima glottidis participates directly in the cough reflex, operating in distinct phases:
- Compression phase (closed): the rima glottidis closes tightly, after which the respiratory and abdominal muscles contract, causing intrathoracic pressure to rise sharply.
- Expulsive phase: the rima glottidis opens abruptly, creating a massive pressure gradient and an airflow velocity ranging from 0.5 to 50–120 m/s to clear mucus and foreign bodies.