Cricoid

The cricoid cartilage, or cricoid, is a ring-shaped hyaline cartilage that forms part of the laryngeal skeleton. It is the only complete ring of cartilage in the larynx, located inferior to the thyroid cartilage and superior to the trachea. Its anterior arch is narrow, while the posterior lamina is broad and can be felt from behind.

Articulations and attachments: The cricoid cartilage articulates with the inferior horns of the thyroid cartilage at the cricothyroid joints, enabling movement that Tenses or relaxes the vocal cords. The broad posterior lamina bears articular facets for the arytenoid cartilages at the cricoarytenoid joints, which control vocal cord movement. The cricoid provides attachment for membranes and intrinsic laryngeal muscles, including the cricothyroid and parts of the inferior pharyngeal constrictor, and forms the base for the upper trachea.

Function: It serves as a rigid, supportive base for the larynx and airway. By providing articulating surfaces for the thyroid and arytenoid cartilages, it participates in voice production and airway protection through its involvement in vocal cord movement and glottic opening.

Clinical relevance: The cricoid is a key landmark in several procedures. Cricothyrotomy, an emergency airway access through the cricothyroid membrane, targets the area near the cricoid region. Cricoid pressure (Sellick maneuver) is used to reduce aspiration risk during induction of anesthesia. Fractures or trauma to the cricoid, though uncommon, can compromise the airway.

Development and variation: The cricoid develops from the laryngeal cartilaginous framework and ossifies with age, though it remains largely hyaline cartilage in adults. Calcification increases with aging and can affect palpation and imaging.

Etymology: The term derives from Latin cricoideus, meaning ring-shaped.