Before we look at the muscles, we need to take a further look at the cartilages of the larynx, then we need to understand the vocal ligaments, and the vocal opening.
In looking at the cartilages, we’ll first revisit the thyroid and cricoid cartilages, which we saw in the last section, then we’ll add to our picture the epiglottic cartilage, and the small but important arytenoid cartilages.
We took a good look at the thyroid cartilage, and the cricoid cartilage in the last section. As we saw, the two cartilages articulate here. When the arch of the cricoid moves up and down, the top of the lamina moves backward and forward. The two cartilages are held together at the front by the strong crico-thyroid membrane, which is part of a larger structure, as we’ll see later.
Now we’ll add the epiglottic cartilage to the picture. The epiglottic cartilage is shaped like a leaf, with a slender stem that’s attached here to the thyroid cartilage.
The epiglottic cartilage is also attached to the body of the hyoid bone by fibrous tissue that runs through this pad of fat. The epiglottic cartilage is covered by mucous membrane here on the back, and on the front down to here. The epiglottic cartilage is highly flexible.
Next we’ll add the arytenoid cartilages to the picture. Here they are. The arytenoid cartilages, which are highly mobile, sit on top of the lamina of the cricoid cartilage, just to each side of the mid-line. They articulate with the cricoid cartilage at these two surfaces.
Here’s the right arytenoid cartilage seen from behind. This tall upward projection is the colliculus. This pointed forward projection is the vocal process. The vocal ligament is attached here.
On the underside, this inward facing articular surface articulates with the cricoid cartilage. Next to the articular surface, this projection on the lateral aspect is the muscular process.
Muscles are attached to the muscular process, and also to the lateral border, and to this broad convex surface, which faces forwards. The top of the colliculus is prolonged by this tiny corniculate cartilage, which faces backwards.
In the intact larynx the arytenoid cartilages are here. When seen from the side, the arytenoid cartilage is here, with the vocal process just in line with the vocal fold. The arytenoid cartilages can move laterally, and medially, and they can rotate about a vertical axis. When the muscular process moves backward and forward, the vocal process is abducted, and adducted.