Cricothyroid Joint
The other main joint of the larynx is the cricothyroid, which makes it possible to move the thyroid cartilage in relation to the cricoid cartilage. We saw a moment ago that the inferior cornua pivot on the cricoid cartilage. On the sides of the cricoid cartilage toward the back is a small raised facet; this articulates with a small facet on the inner surface of the inferior cornu (Fig. 2-6). This synovial joint is bounded by three ligaments. The posterior ceratocricoid ligament attaches toward the upper sides of the cricoid plate and runs downward and outward to attach to the inferior cornu of the thyroid. The lateral ceratocricoid ligament connects the inferior cornu with the side of the cricoid cartilage. Finally, the entire articulation is enclosed within a capsular ligament lined with a synovial membrane that lubricates the joint (see inset, Fig. 2-3).
Figure 2-6. Cricothyroid joint.
Two movements take place at this joint: a rocking or pivoting of the thyroid cartilage in relation to the cricoid; and the thyroid can glide forward out of its articulation to move forward in relation to the cricoid cartilage. These actions, as we’ll see later, stretch the vocal folds during vocalization and raise the pitch (Fig. 2-6; see also Fig. 2-18).