Vocal Tract Anatomy

We use several systems to produce voice. This post will give a general introduction to vocal tract anatomy. A post in the near future will further explain how the three subsystems of voice function to make voice (physiology). Another future post will deal with the intricate anatomy of the larynx. There is just so much information, I couldn’t put it all together in one post!

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The Three Subsystems of Voice

There are three subsystems of voice, which we will talk much more about in an upcoming post. But, they are important to give us a framework from which to discuss the anatomy. The three subsystems are: respiration, phonation, and resonation. These roughly equate to the lungs/respiratory tract, larynx (voice box), and space in the mouth, throat, and nose. 

The Lungs and Respiratory Tract – The Powerhouse of the Vocal Tract

Respiratory anatomy is very detailed. I’m not going to go into the tiny details about the make-up of the cells in the lungs. Instead, I want to talk about the gross structure of the lungs, diaphragm, and airway. The lungs are responsible for moving air (especially oxygen) into the body (inhalation), providing oxygen to the blood stream, and the discharging the waste product (CO2) through exhalation. 

The diaphragm is a dome-shaped muscle that cuts the heart and lungs off from the viscera (organs in the abdomen). The diaphragm flattens, and displaces the viscera. This is what causes your belly to move away from your spine during inhalation. The flattening of the diaphragm also causes the pressure in the lungs to decrease. This leads to air flowing into the lungs. As air is exchanged, the abdominal muscles and rib muscles assist in pushing the air out of the lungs. The speed of air release depends on the speed of abdominal and rib muscle movement. The diaphragm returns to a domed shape during exhalation. Then the process ensues again.

The respiratory tract is above the lungs. Several tubes of different thicknesses make up the respiratory tract. These tubes are the trachea, bronchi, and bronchiole tubes. The tubes get smaller as they move into the lungs themselves. The tube we talk the most about in singing is the trachea. The trachea is important because it allows air to flow into and out of the lungs.

The Larynx: Anatomy to the Cartilage/Bone and Muscle Levels

Bone and cartilage structures

The larynx sits right at the top of the trachea. It is made up of several cartilages: thyroid, cricoid, 2 arytenoids, the epiglottis, and some tinier cartilages called the cuneiform and corniculate cartilages. 

The thyroid cartilage is shaped like a shield. It makes up the entire front of the larynx. You can feel the thyroid cartilage through the neck beginning at the Adam’s apple. The cricoid cartilage is ring-shaped (like a signet ring). It is the main attachment point to the trachea, and sits just below the thyroid cartilage. The arytenoid cartilages are in the back of the larynx. They allow the vocal folds to open and close. The arytenoid cartilages connect to the cricoid cartilage as well. The cuneiform and corniculate cartilages sit on top of the arytenoid cartilages. Finally, the epiglottis, is a curved and fan-shaped cartilage at the top of the larynx. It is important during swallowing to protect the airway. 

The hyoid bone is the only floating bone in the body. This means it does not articulate with any other bones. The larynx suspends from the hyoid bone. The hyoid bone attaches to the tongue muscles and the sternum as well. 

Muscles of the larynx

Several muscles make up the larynx. There are muscles that start and end within the larynx (intrinsic muscles), and there are muscles that only begin or end in the larynx (extrinsic muscles). Swallowing is the primary function of the extrinsic laryngeal muscles; however, they sometimes find use with voicing. I’m not going to address them singly for this post, but there are lots of different resources that will provide you with explanations of the use of these muscles. 

The intrinsic muscles are the ones we use predominantly for voice and breathing. They include the following paired muscles: thyroarytenoids, cricothyroids, posterior cricoarytenoids, lateral cricoarytenoid muscles, and the interarytenoids. The thyroarytenoids and cricothyroid muscles are known as the “tensor” muscles. These two muscle groups are responsible for pitch change. The lateral circoarytenoids and the interarytenoids are most responsible for vocal fold closure. The posterior cricoarytenoids are the sole muscle group for opening the vocal folds to allow for adequate breathing. 

The Resonating Cavities – The Vocal Tract Anatomy that Shapes Our Voices

I’m not going to go far into the anatomy of the mouth and throat, but what I do want you, as a professional voice user, to recognize: the way you move the muscles in your mouth and throat affects vocal production. Tongue base tension will pull on the hyoid, which then sets the larynx in a higher position. This reduces the amount of space in the throat, and changes the resonance. Your soft palate changes airflow through the nose. Too much space, and you’re hypernasal. Too little space, and you’re hyponasal. We’re always looking for balance. The amount of space you create by opening your mouth also affects resonance. Bigger space means bigger resonance. 

There are more intricate details that I could share. These intracacies are too detailed for a general anatomy and physiology post. Some future posts will address my understanding of registration and genre in relation to anatomy and physiology. I will also have a post sometime soon about the layers of the vocal folds. In the meantime, I wish you success on your wellness journey!