The Framework of the Larynx
The hyoid bone, the thyroid, cricoid, and arytenoid cartilages, the epiglottis, and the tiny corniculate and cuneiform cartilages form the complete framework of the larynx (Fig. 2-3). The thyroid cartilage is the most prominent part of the larynx (Fig. 2-4). Where the two plates of the thyroid join in front, they angle sharply forward in men, forming the prominent bump called the Adam’s apple. The sides of the plates, or lamina, are rather smooth except toward the back, where a ridge, beginning at a tubercle or protrusion, runs down and forward to the lower border of the lamina, forming the oblique line. At the back part of each lamina there is a long upward projection called the superior cornu. Just above the thyroid cartilage is the U-shaped hyoid bone. This bone, which forms the root of the tongue, is an important part of the framework of the larynx because the larynx is suspended from the hyoid bone by a ligament attaching to the superior comu, as well as by the thyrohyoid membrane. A downward projection from the back part of the lamina, called the inferior cornu, forms a pivot with the sides of the cricoid cartilage (Fig. 2-4).
Figure 2-3. The framework of the larynx.
Figure 2-4. Thyroid, cricoid, and arytenoid cartilages.
The cricoid, or ring, cartilage was given this name because of its resemblance to a signet ring—a ring with a large flat surface for imprinting one’s seal. The front of the cricoid is narrow, not much thicker than the rings of the trachea below it; the back is thicker because it serves as attachment for the muscles that abduct, or open, the vocal folds, and as a surface area for the arytenoid cartilages (Fig. 2-4).
The arytenoid cartilages, when placed together, resemble a pitcher; hence their name (from the Greek word for pitcher). Because of their shape, the arytenoids are also sometimes called the “pyramid cartilages.” At its base, the arytenoid forms a joint where it sits on the cricoid cartilage; there are also two protrusions or angles, the muscular process and the vocal process. The muscular process projects outward and backward and serves as attachment for the posterior and lateral cricoarytenoid muscles; the vocal process projects anteriorly and serves as attachment for the vocal folds (Fig. 2-4).