The cricoid cartilage is a key component of the larynx, commonly known as the voice box. This ring-shaped structure is composed of hyaline cartilage, a resilient, flexible connective tissue. It serves as a base for other laryngeal cartilages and forms part of the upper airway framework. It is essential for breathing and voice production.
Where It Is Located
The cricoid cartilage is situated at the base of the larynx, directly below the thyroid cartilage (Adam’s apple). Below, it connects to the top ring of the trachea (windpipe). This placement makes it a transition point between the larynx and the lower respiratory tract.
Its distinct shape resembles a signet ring, with a narrow arch at the front and sides that broadens into a plate-like structure at the back. This posterior broad portion is known as the lamina. The cricoid cartilage completely encircles the airway, unlike the C-shaped rings of the trachea. It is located roughly at the level of the sixth cervical vertebra (C6) in the neck.
Its Essential Roles
The cricoid cartilage primarily provides structural support to the airway. As the only complete ring of cartilage in the entire airway, it prevents the collapse of the upper respiratory passage, ensuring an open route for airflow. This structural integrity is maintained even during changes in air pressure.
The cricoid cartilage provides a stable platform for the attachment of other laryngeal cartilages, the arytenoid cartilages. These cartilages sit atop the posterior lamina of the cricoid and are instrumental in vocal cord movement. The cricoid also serves as an attachment point for various laryngeal muscles and ligaments, including the cricothyroid muscle.
These attachments allow for the coordinated movements of the vocal cords, which are important for voice production. By supporting the arytenoid cartilages and providing leverage for muscle action, the cricoid cartilage indirectly influences the tension and position of the vocal cords. This allows for changes in pitch and volume during speech.
Why It Matters Medically
The cricoid cartilage is significant in medical practice, particularly in emergency and surgical settings. Its palpable location in the neck, just below the thyroid cartilage, makes it a reliable anatomical landmark for various procedures. For instance, in situations requiring immediate airway access, such as a cricothyroidotomy, medical professionals locate the membrane just above the cricoid to establish a temporary breathing tube.
Historically, the cricoid cartilage was involved in the Sellick maneuver, where pressure was applied during rapid sequence intubation. The intention was to compress the esophagus, which lies directly behind the cricoid, to prevent stomach contents from entering the lungs during the procedure. However, current research suggests that the benefits of this maneuver may not be as significant as once thought, and its widespread recommendation has declined.
Understanding the dimensions of the cricoid cartilage is important for selecting the correct size of endotracheal tubes used to ventilate patients. Variations in its internal diameter can influence the ease and safety of tube placement. The cricoid cartilage’s role in maintaining airway patency makes it a focus in conditions affecting the larynx, such as subglottic stenosis, where narrowing occurs just below the vocal cords.