3.2.1.1. The cricoid cartilage
If we start at the bottom of the larynx, we find the cricoid cartilage forming a ring with an expansion posteriorly, almost like a signet ring. Like the thyroid and the arytenoids, the cricoid is made of hyaline cartilage that usually ossifies with age (Drevet, Conti, &
Deslauriers, 2016). The cricoid can be seen as a continuation of the tracheal cartilages, which are also made of hyaline, but the cricoid differs from them by being a completed ring. The tracheal cartilages are C- or U-shaped, with muscle tissue closing the gap at the back. They are separated from each other by annular intercartilaginous ligaments, which make the trachea flexible. Between the last tracheal cartilage and the cricoid is the cricotracheal ligament. The cricoid serves as a stabilization point for the rest of the larynx (Drevet et al., 2016), but can, according to the Estill Voice Model(Steinhauer et al., 2017, pp. 103-114) be tipped
downwards anteriorly. This is called a cricoid tilt and is presumed to be important for safe belting. This issue will be further examined later on. Posteriorly on top of the ‘signet part’ of the cricoid, we find the facets for each of the two arytenoids, and laterally on both sides of the cricoid are the facets for articulation with the inferior horns of the thyroid cartilage.
3.2.1.2. The thyroid cartilage
The thyroid cartilage is a movable cartilage, made up of two plates that have grown together frontally, almost like the bow of a ship. It is the larynx’s largest cartilage and is connected to the cricoid cartilage on both sides laterally at the cricothyroid joint. It also connects to the cricoid by the cricothyroid membrane, which will be described below. Posteriorly on either
side of the thyroid cartilage, we find two ‘horns.’ One pair faces upwards and the other downwards. It is this downward facing horn, the inferior cornu, that connects to the cricoid at the cricothyroid joint. The superior cornu, the other paired horn, is attached to the hyoid bone by the lateral thyrohyoid ligament. This ligament forms the posterior margin of the larger
thyrohyoid membrane, which runs along the upper border of the thyroid and extends up to a
bursa, a small fluid-filled sac, that is attached to the hyoid bone. This bursa “facilitates the ascent of the larynx during swallowing” (McHanwell, 2016, p. 590).
Figure 1. Sideview of the larynx.
The whole larynx is enlarged during puberty, but especially the thyroid cartilage where the sharpness of the thyroid’s anterior angle is enhanced. This projection at the front of the neck is also known as the Adam’s apple, and is usually much more prominent in men than in women. It is because of these larger-sized larynges and thus longer vocal folds that men usually have a deeper speaking voice than women and children. Somewhat further down on the other side of this projection of the thyroid’s anterior surface, inside the larynx, we find the articulation point where the vocal folds are attached. A more detailed description of the vocal folds follows in due course, but for now it will suffice to mention that they stretch backwards horizontally from the thyroid’s inside and connect to the vocal processes of the arytenoid
3.2.1.3. The arytenoid cartilages
The arytenoid cartilages are a pair of pyramid-shaped cartilages, with two processes on each cartilage. The vocal process projects forward, and this is the corner where the vocal ligament and thyroarytenoid muscle are attached. The second of the two processes projects out laterally and is called the muscular process. This is the attachment point for abducting and adducting musculature which will be described on pages 39-40. The third low corner of the pyramid is the base, and this is the contact point between the arytenoids and the signet part of the cricoid cartilage, on which they are situated. The contact point between them is called the
cricoarytenoid joint and facilitates the rotating and gliding motion necessary for phonation (McHanwell, 2016, p. 589). On top of each arytenoid, on the apex, there are two smaller elastic cartilages called the corniculate cartilages. Somewhat higher and laterally we also find the elastic cuneiform cartilages. These paired fibrocartilages are found in the tissue of the aryepiglottic fold and follow the arytenoids’ motions. They support both the vocal folds and the lateral aspects of the epiglottis.
3.2.1.4. The epiglottis
The epiglottis is a leaf-shaped elastic fibrocartilage fastened inside the thyroid by the
thyroepiglottic ligament, just above the vestibular folds, which will be described further
below (Drevet et al., 2016). From this stem-like shape, the epiglottis projects upwards
obliquely and folds out like a heart-shaped leaf or tongue. If we look at the epiglottis from the side, it is slightly curved, and midway on the anterior surface it is attached to the hyoid bone by the hyoepiglottic ligament. The epiglottis’ shape and curvature vary from person to person but it is often slightly concave when seen from above through a mirror or fiberscope.
Generally, children’s larynges have more of an omega-shaped epiglottis, when seen from above, but this may also be just a variation in normal human anatomy (Colton, Casper & Leonard, 2006, pp. 379-380). Regardless, the epiglottis’ upper margin is free, and it ‘bows’ over the rest of the larynx when we swallow, thus closing the airway passage conjointly with the closed vocal folds and the vestibular folds. In addition to this mechanism, the aryepiglottic
fold helps seal off the area so that food and liquid pass into the esophagus. In singing
literature, the tube made by the aryepiglottic fold has many names. It is called the epiglottic
funnel in Complete Vocal Technique (CVT) (Sadolin, 2008) and the aryepiglottic sphincter in
the Estill Voice Model (EVM) (Steinhauer et al., 2017). Titze (as cited in Sundberg, 2003, p. 11) refers to it as the epilaryngeal tube. This tube can be wide open or narrowed until
(Sadolin, 2008, pp. 51-52; Sundberg & Thalén, 2010, p. 654). In the EVM, this ‘bowing’ motion, the narrowing of the aryepiglottic sphincter (Narrow AES), is a necessary trait in the “Voice Quality” called “Twang” (Steinhauer et al., 2017, pp. 115-126). In other words, the EVM does not use the word twang to describe this specific motion, the narrowing of the AES, but as a label for a more complex setup that includes a special soft palate position, positioning of the vestibular folds, and so on. Because twang implies special characteristics of the sound that are not always present even though the AES is narrowed, the EVM has chosen not to use the term for the AES narrowing. A twangy sound “is often identified as a feature in … Country, Broadway mix and belt styles” (Steinhauer et al., 2017, p. 125), but a dramatic operatic tone is rarely thought of as twangy. Nevertheless, narrowing of the AES has been shown to be present in resonant and ringing operatic tones, making the term twang somewhat confusing.
In my opinion, it does not make any difference whether the teacher uses the term AES narrowing or says to the student, ‘Add more twang,’ referring to the twanging of the epiglottic funnel (CVT). Both terms work equally well, provided that the teacher and student agree on which terms to use.
Inside the aryepiglottic fold we find the upper margin of the larger quadrangular
membrane. This membrane is attached on both sides of the epiglottis and stretches backwards
and downwards. Posteriorly it connects to the corniculate cartilages and the upper half of the arytenoids above the vocal processes. This forms a free upper border, with the stabilizing cuneiform cartilages embedded in the tissue. This area between the epiglottis and the
arytenoids also encompasses the aryepiglottic muscle, which will be described further below. Along the epiglottis’ lateral edges, downwards and towards the front, the quadrangular membrane continues and attaches to the inside of the thyroid cartilage, above the true vocal folds but below the thyroepiglottic ligament. This forms a line between the thyroid and the two arytenoids, and this free, lower and thicker border of the quadrangular membrane is called the vestibular ligament.