What structure forms the lower portion of the larynx?

The structure that forms the lower portion of the larynx is the cricoid cartilage. The larynx, also known as the voice box, is a complex structure located in the throat, and it plays a critical role in protecting the airway and facilitating phonation (the production of sound).

The cricoid cartilage is a ring-shaped structure that sits below the thyroid cartilage and above the trachea. It is the only complete ring of cartilage in the airway, providing support and maintaining the patency of the airway. Its position at the base of the larynx makes it a crucial anatomical landmark and functional component in both the respiratory system and the processes of swallowing and sound production.

In comparison, the thyroid cartilage forms the bulk of the laryngeal framework but is situated at the upper portion, while the epiglottis acts as a flap that covers the trachea during swallowing to prevent food from entering the airway. The arytenoid cartilages are located on top of the cricoid cartilage and play roles in the vocal cord movements but do not constitute the lower portion of the larynx.