HOW VOICES WORK:BASIC VOCAL ANATOMY AND PHYSIOLOGY
We begin this exploration by focusing primarily on anatomy. Anatomy has to do with study ofthe body’s structure and form. Latter portions of this section also include some conceptualgroundwork in physiology. Physiology addresses how body structures actually work andfunction.
The explications that follow are designed to assist those with limited scientific backgrounds (thatis, most choral-vocal music majors) to “get ready” for more in depth explorations found inbooks, research studies, and other media authored by voice scientists. In other words, theintention here is to offer a simultaneously accurate and “user-friendly” sequence of some basicfacts and concepts.
Even so, many students, particularly pre-professional undergraduates, may balk initially at theprospect of engaging with such material. It is human nature to ask, “Why do I have to learn thisstuff?” This query, as is the case with most questions, is a logical and very appropriate one topose.
There is, as indicated in the introduction to this chapter, a reasonable, even compelling answer tothat question. It bears repeating here: “Because you work, or shortly will work, in a professionalcapacity with living human beings. Imprecise or just plain wrong understandings of vocalanatomy and physiology on your part, no matter how well-intentioned or sincerely held, can (a)potentially harm those persons entrusted to your care and (b) prevent you from devisingstrategies and learning opportunities that can actually help people achieve their fullest vocal andhuman potentials.”
Bluntly but succinctly put, ignorance of vocal anatomy, physiology, and acoustics is not anoption for twenty-first century choral-vocal professionals. That said, let us roll up our sleevesand attend to the professional business now at hand.
The Larynx
Definition and Description
The larynx (pronounced LAIR-inks) is a mobile body organ located in the neck. It is situated (a)in front of the spinal column, (b) below the base of the tongue, and (c) in front of and adjacent tothe esophagus (the pathway for food and liquid from the mouth to the stomach). See Figure 3.1.
The larynx basically forms a somewhat flexible, connecting tube. It is about one to twocentimeters (or roughly 1.5 inches) long in adults. Sometimes the larynx is referred to,informally, as the “voice box.” It connects directly (a) to the respiratory system below it (trachea
[windpipe], bronchi, and lungs) and (b) to the vocal tract above it (the throat directly above thelarynx, along with the oral cavity [mouth]).
Figure 3.1. Location of the larynx, sagittal view.Image from GetBodySmart.com [permission pending]
The larynx houses the vocal folds. As a unit, the larynx is largely suspended from a single bone,the hyoid (See Figure 3.2), which itself is suspended from the base of the skull by variousmuscles and ligaments. The fact that the larynx is suspended from the hyoid bone contributes tothe capacity of the larynx as a whole to move up and down, and for various of its parts to gentlyslide, tilt, rotate, or rock back and forth.
Figure 3.2. The hyoid bone and suspension of the larynx, anterior view.
Also attached to the hyoid bone is the root of the tongue. From the hyoid bone the tongue, ofcourse, extends upward into the mouth. During swallowing, the base of the tongue movesbackward and downward, while the larynx is drawn simultaneously forward and upward. In thisfashion the base of the tongue shields and protects the larynx.
The plural of larynx is larynges (pronounced lairINgees). The adjectival form of the term islaryngeal (pronounced either lairinGEEul or lairINjul), as in “laryngeal cartilages.”
SIDEBAR: Viewing Anatomical Diagrams and Pictures.
By custom, anatomical diagrams and pictures typically are labeled by terms that give the viewerimportant information about the angle, attitude, or direction of the body parts depicted. Forexample, Figure 3.1 is labeled a sagittal or side view of the larynx. Such information assists invisualizing spatially the orientation of particular body parts as they are represented in variousdiagrams and pictures.
Among some basic, descriptive terms to know are:
Supra- a prefix meaning above or overSub- toward the front
Anterior: a prefix meaning below or underPosterior: toward the back
Superior: toward the topInferior: toward the bottom
Medial: toward the midline or mid plane of the body
Lateral: toward the body’s sides, away from the midline
Sagittal: an imagined anatomical plane that separates the bodyinto right and left sides; a side view
Transverse: an imagined anatomical plane that divides the bodycrosswise; a perpendicular orientation
Oblique: a diagonal or sloping orientation
These descriptors may be combined. For example, a view or depiction of the larynx labeled“anterolateral” combines the descriptors anterior and lateral. Such a view would encompass thefront and side of a particular body part, or portion thereof.
An important point to remember when viewing anatomical depictions is that such figuresinvariably simplify matters in order to advance particular understandings. Thus they mayobscure purposely the overall complexity, even seeming “messiness,” of how particular humanbody parts relate to other body parts.
It is not absolutely necessary for choral conductor-teachers to know all of the various tissues,muscles, membranes, ligaments, blood vessels, nerves, joints, and glands that surround,transverse, or weave in and out of those body parts of particular interest to singers and singingpedagogues. After all, their professional duties do not include practicing medicine or performingsurgery. But choral conductor-teachers should keep the presence of such complexity in mind.Otherwise, simplistic impressions may ensue. Such initial impressions can be difficult to unlearnlater.
Purposes of the Larynx
Singers sometimes presume the sole purpose of the larynx is voice related, i.e., to facilitatespeech and song. Yet the larynx serves several functions in the human body. Primary amongthem is survival.
Recall that the larynx is positioned atop the trachea (the windpipe that provides a pathway for airentering and exiting the lungs). Recall also that the larynx lies adjacent to the esophagus. Theesophagus is a pathway for food and liquid (and even post-nasal mucous or “drip”) to traversedownward into the stomach. On occasion, moreover, the esophagus serves as the route by whichacid or other content from the stomach, e.g., vomit, finds its way upward into the throat. Fromits strategic location atop the trachea and beside the esophagus, the larynx protects the lungs. Asa unit, the larynx functions as a valve to prevent foreign substances from entering the lungs by(a) closing off the tracheal airway and (b) triggering a cough reflex when unwelcome matterstarts to invade its territory.
The larynx also plays a role in maintaining the ecology of delicate lung tissues. It assists in theregulation of lung temperature, humidity, and air pressure. With respect to the latter, forinstance, the larynx closes the tracheal airway during such biological actions as swallowing,lifting, childbirth, and defecation.
Singers and choral teacher-conductors are rightly curious about the larynx because of its criticalrole in human speech and song. But the major evolutionary and ongoing biological purpose ofthe larynx is its function in swallowing, coughing, vomiting, and regulation of lung ecology. AsMargaret Clegg (2000) observes, evolution of the modern human larynx as associated with fullyupright posture evidently values protection of the airway over sustaining a capacity to vocalize.
Structural Scaffolding of the Larynx: Laryngeal Cartilages
As a unit, the larynx contains six cartilages that provide structural support for its variousoperations. Cartilage is a type of tough, yet semi-flexible, skeletal tissue. It is softer than bone,but harder than ligament.
There are three paired and three unpaired cartilages in the larynx. The epiglottis, thyroid, andcricoid cartilages are unpaired, that is, single entitites. The arytenoids, corniculates, andcuneiforms are paired, meaning there are two of each.
The epiglottis is comprised of elastic cartilage that does not ossify, or harden, with age.Generally speaking, all other laryngeal cartilages are comprised largely of hyaline cartilage,which does ossify with age, thus eventually limiting some laryngeal flexibility in older persons.
Take time now to master the names and relative locations of these laryngeal cartilages. SeeFigure 3.3. Just as these cartilages provide scaffolding for the larynx, so can they affordconceptual scaffolding to facilitate subsequent learning about how human voices work.
The thyroid cartilage is the largest of the laryngeal cartilages. It looks roughly like a crescentshield. Sometimes it is compared to a visor of the sort found on the helmet of a MedievalKnight, because it somewhat resembles that kind of visor in both appearance and movement.
The thyroid cartilage consists primarily of two plates (called laminae), a top-center anteriornotch, and two projections on either side (See Figure 3.3). The upward rising part of eachprojection is called a superior cornu. The descending part of each projection is known as aninferior cornu. The inferior cornua join to the cricoid cartilage. The superior cornua connectwith ligaments to the hyoid bone. The thyroid cartilage is open in the back.
Figure 3.3. The thyroid cartilage (a) anterior-sagittal view and (b) various views.
The anterior (front) joining of the laminae forms an angle. Males in puberty and beyondtypically display smaller angles than women or pre-pubertal children, resulting in a largerprominence at the point where the laminae join. This laryngeal prominence, especially evidentin skinny or thin-necked persons, is referred to colloquially as the “Adam’s apple.”
Put your finger on your throat and touch this comparatively large protrusion. This maneuver,aside from its value in locating the anterior thyroid cartilage, also affords a convenient way tolocate the relative anterior position of the vocal folds. The vocal folds attach anteriorily (at theapex of their V configuration) on the inside of the thyroid cartilage, at a point known as theanterior commissure. See Figure 3.4.
Figure 3.4. Anterior attachment of vocal folds to the thyroid cartilage at the anterior commissure,superior views.
Cricoid Cartilage
The cricoid (pronounced CRY-koyd) cartilage lies just beneath the thyroid cartilage. It forms aring fully surrounding the laryngeal airway. It makes sense to think of the cricoid cartilage as theuppermost ring of the trachea (windpipe). The cricoid ring, however, is wide and tall in theback, lending it a “signet ring” appearance (See Figure 3.5).
Anteriorily (at the front), the cricoid can move upward toward the thyroid cartilage in response torotation of the cricothyroid joint (formed by the attachment of the cricoid cartilage to the inferiorcornu of the thyroid cartilage). Posteriorily (at the back), the cricoid cartilage attaches to thearytenoid cartilages.
The uppermost laryngeal cartilage is the epiglottis. It resembles a shoehorn or a long leaf. SeeFigure 3.6. The base of the epiglottis is attached to the inside, anterior (front) rim of the thyroidcartilage, just below the thyroid notch.
The elasticity of the epiglottis (recall that it does not harden with age) permits it both (a) to foldalong its midline and (b) to move forward to close or seal off the laryngeal airway as it is pushedbackwards by the tongue. By such movement the epiglottis diverts food and liquid toward theesophagus during swallowing. The epiglottis also triggers a cough reflex to repel foreignparticles that may come in contact with it in its sealing position. When the tracheal airway isopen, the epiglottis may function as an acoustic resonator.
Figure 3.6. Epiglottis, anterior and sagittal views.
Paired Laryngeal Cartilages
Three laryngeal cartilages are paired. That is, they are present in groups of two. Figure 3.7illustrates these paired cartilages: the arytenoids, the corniculates, and the cuneiforms.
The arytenoid (pronounced ah-RIH-teh-noid) cartilages are positioned atop the posterior (or“signet”) portion of the cricoid cartilage (Review Figure 3.3, posterior view, once more). Theyconnect to the cricoid cartilage via the cricoarytenoid joints. Each of the three-sided, pyramid-shaped arytenoid cartilages has four surfaces: anterior, lateral, medial, and a base.
The arytenoid cartilages can move rather rapidly on two planes: (a) sideways, or laterally, to andfrom a midline point; and also (b) back to front, with a posterior to anterior movement. Toachieve these directional movements, the two arytenoid cartilages can rotate, tilt, and glide insynchronous choreography.
Such movements are important, because the vocal folds connect posteriorily (at the wings oftheir V shape) to the arytenoid cartilages. This point of connection, on the anterior angle at thebase of each arytenoid cartilage, is known as the vocal process.
When the arytenoids move, they play major roles in abducting (moving apart or separating) andadducting (bringing together) the vocal folds. The arytenoids, in other words, function asopener (abductor) and closer (adductor) cartilages. In performing these functions, the arytenoidsfacilitate vocal fold motion and also produce changes in the shape of the vocal fold edges.
You will need to know the terms abduction and adduction. Alas, these words both look andsound similar. A helpful way to remember their meanings is by reference to their prefixes, ab-and ad-. In Latin, ab denotes away from (think abstain), while ad means to or toward (thinkadditive).
The corniculate (pronounced corNIHcueluht) cartilages are situated immediately above andjoined to the superior tips of the arytenoid cartilages. The corniculates, along with the superiortips of the arytenoids, form posteriorward horns or cornua, hence their name. (Review againFigure 3.3, posterior view).
Cuneiform Cartilages
The cuneiform (pronounced CUEnihform) cartilages are embedded in the muscle of thearyepoglottic fold parallel to the epiglottis and just above, but separated from, the corniculatecartilages. You need not bother with them. These tiny, rod-like cartilages simply support thesoft tissues of the aryepiglottic folds, which connect the arytenoid cartilages to the epiglottis.Otherwise, they appear to serve no known function from the standpoint of speech and singing.
The terms larynx and pharynx (pronounced FAIR-inks) sound alike. As we have learned, thelarynx houses and protects the vocal folds. Its cartilages form a somewhat flexible tube, aboutone to two centimeters in length, which connects the respiratory system to the throat area directlyabove the larynx. This throat area is the pharynx.
The pharynx, as the term is typically employed, denotes that area extending from the top of thelarynx all the way up to the velum, or soft palate, in the roof of the mouth. This combined throatand mouth area comprises what is commonly called the vocal tract.
However, the bottom part of the pharynx also partially surrounds the upper laryngeal tube orepilarynx area. In this bottom part of the pharynx, moreover, there are two cavities, one on thefront right side of the laryngeal tube and one on the front left side, known as the piriform sinusesor recesses. These pear-shaped cavities (Figure 3.8, Figure 3.9), located to the rear of thearytenoids and laterally to the aryepiglottic folds (which separate these cavities from the larynx),contain openings to the esophagus (the pathway tube to and from the stomach). Food and liquidpass through these openings.
Figure 3.8. Anterior wall of the pharynx viewed from behind. The pharynx communicates with the nasalcavity, auditory tubes, oral cavity, larynx and esophagus.
Figure 3.9. Piriform sinuses and aryepiglottic fold viewed from above.
