Overview
The larynx is a complex biomechanical structure that serves multiple critical functions: protecting the airway during swallowing, enabling respiration, and producing voice. Understanding laryngeal anatomy is fundamental to voice science, as the intricate interplay of cartilages, muscles, and soft tissues determines how sound is generated and modulated.
Much of the laryngeal action is reflexive, responding automatically to physiological demands throughout the body. The larynx does not function in isolation—it is intimately connected with structures throughout the head, neck, and chest. This chapter provides a foundation for understanding how these anatomical components work together to enable phonation.
The laryngeal framework consists primarily of cartilage rather than bone, allowing for the mobility essential to swallowing, breathing, and voicing. The vocal folds themselves are highly specialized structures with a layered tissue composition that facilitates vibration. Intricate muscle systems control vocal fold position and tension, while extrinsic muscles position the entire larynx within the neck.
What You’ll Learn
Structural Framework
- Cartilaginous skeleton: Thyroid, cricoid, and arytenoid cartilages that form the laryngeal framework
- Hyoid bone: The floating bone that anchors laryngeal structures
- Directional terminology: Standard anatomical terms for describing laryngeal structures and their relationships
Muscle Systems
- Intrinsic muscles: Internal muscles that control vocal fold position, length, and tension
- Extrinsic muscles: External muscles that position the larynx within the neck
- Agonist-antagonist relationships: How opposing muscle groups work together for fine motor control
Vocal Fold Tissue
- Layered structure: Epithelium, lamina propria (superficial, intermediate, deep layers), and muscle
- Cover-body theory: Understanding the vocal folds as a vibrating system with distinct mechanical properties
- Tissue composition: Elastin and collagen fiber organization that enables both flexibility and strength
Support Systems
- Vascular supply: Blood vessels providing oxygen and nutrients to laryngeal tissues
- Innervation: Nerve pathways controlling voluntary and reflexive laryngeal functions
- Protective mechanisms: Anatomical adaptations that prevent injury during phonation
Clinical and Pedagogical Relevance
Understanding laryngeal anatomy is essential for multiple professional applications. Voice clinicians use anatomical knowledge to diagnose pathologies, plan treatments, and explain voice disorders to patients. Voice teachers apply anatomical principles to help singers and speakers develop healthy technique. Researchers rely on accurate anatomical models to study phonation mechanics and develop new interventions.
The “whole body” approach to voice emphasizes that laryngeal function cannot be separated from the respiratory, postural, and resonatory systems. A singer’s breath support, a patient’s vocal fold paralysis, or an actor’s vocal fatigue—all can be better understood through knowledge of the anatomical structures involved.
This chapter establishes the anatomical foundation upon which all subsequent discussions of voice production will build. Master these structural concepts to develop a comprehensive understanding of how voice works.
Check Your Understanding
Five short questions on the core ideas of this chapter. Each one explains itself as soon as you answer, so treat them as a way to test your reasoning rather than a test to pass. Revisit any topic above first if you like.
Correct Not quite Best answer
The muscular process is a lever arm projecting laterally from the base of the arytenoid. The lateral cricoarytenoid, arriving from the cricoid arch in front, pulls that lever forward and medially; the arytenoid rotates and the vocal process—where the vocal ligament attaches—moves toward the midline (adduction). The posterior cricoarytenoid, arriving from the back of the cricoid lamina, pulls the same lever backward and laterally, rotating the arytenoid the opposite way and swinging the vocal process outward (abduction). Same lever, opposite lines of pull.
Correct Not quite Best answer
The vocal process is the anterior projection of the arytenoid that anchors the vocal ligament—it is the posterior end of the vocal fold itself, not an insertion for either cricoarytenoid muscle. The chapter places both the lateral and the posterior cricoarytenoid on the muscular process. What differs is where each muscle comes from, and therefore the direction it pulls.
Correct Not quite Best answer
Both cricoarytenoid muscles are innervated by the recurrent laryngeal nerve; the only intrinsic muscle supplied by the superior laryngeal nerve is the cricothyroid. And a muscle's nerve supply does not set its direction of pull—its origin and insertion do.
Correct Not quite Best answer
Both muscles move the arytenoid on top of the cricoid, so both act at the cricoarytenoid joint. The cricothyroid joint is a different articulation—between the inferior cornua of the thyroid cartilage and the cricoid—where the cricothyroid muscle rocks the two cartilages to lengthen the vocal folds for pitch.
The thyroarytenoid runs from the inside of the thyroid cartilage back to the arytenoid and forms the bulk of the vocal fold. Contracting it draws the arytenoid forward, shortening and thickening the fold and increasing its mass per unit length—the antagonist of the cricothyroid.
Choose an answer for this row, then check again.
Both parts of the cricothyroid (pars recta and pars obliqua) span the cricoid arch and the thyroid cartilage. Contraction rocks the two cartilages at the cricothyroid joint, increasing the distance between the thyroid cartilage and the arytenoids, which stretches and tenses the vocal folds and raises pitch.
Choose an answer for this row, then check again.
From the lateral cricoid arch to the muscular process. Pulling the muscular process forward and medially rotates the arytenoid so the vocal processes meet, closing the membranous (anterior) part of the glottis.
Choose an answer for this row, then check again.
From the posterior cricoid lamina to the muscular process. Pulling the muscular process backward and laterally rotates the arytenoid so the vocal processes separate. It is the only intrinsic muscle that opens the glottis, which is why losing it on both sides is an airway emergency.
Choose an answer for this row, then check again.
The transverse and oblique interarytenoid fibers run between the two arytenoid cartilages. Contraction draws the arytenoids toward each other, sealing the cartilaginous (posterior) glottis—the part the lateral cricoarytenoid alone leaves open.
Choose an answer for this row, then check again.
Correct Not quite Best answer
The sternothyroid runs from the sternum straight to the oblique line of the thyroid lamina—the only strap muscle that attaches to the laryngeal framework itself. Its contraction pulls the thyroid cartilage, and with it the larynx, downward without any intermediary, which is why the chapter calls it the most direct laryngeal depressor.
Correct Not quite Best answer
The sternohyoid also pulls downward from the sternum, but it inserts on the hyoid bone, not on the larynx. It lowers the larynx only indirectly, through the thyrohyoid membrane and the other connective tissue linking the hyoid to the thyroid cartilage.
Correct Not quite Best answer
The thyrohyoid connects the thyroid cartilage to the hyoid, and its effect depends on which end is held still: with the hyoid fixed by the suprahyoid muscles it raises the larynx toward the hyoid; with the larynx fixed it pulls the hyoid down. It is not a reliable laryngeal depressor.
Correct Not quite Best answer
The cricothyroid is an intrinsic muscle: both ends attach to laryngeal cartilages, so it can change the relationship between the cricoid and thyroid (lengthening the vocal folds and raising pitch) but cannot move the larynx up or down in the neck. Laryngeal height is set by the extrinsic muscles.
Correct Not quite Best answer
That describes the deep layer of the lamina propria, whose nearly inextensible collagen fibers run front to back and, together with the intermediate layer, make up the vocal ligament. Stiff, stretch- resisting tissue is exactly what the cover is not; the deep layer belongs to the body.
Correct Not quite Best answer
Only the thyroarytenoid muscle can contract. It lies deepest, forms most of the fold's mass, and is the core of the body. The superficial lamina propria contains no muscle fibers and cannot change its own stiffness.
Correct Not quite Best answer
The superficial layer is roughly 0.5 mm of loosely arranged elastin fibers in interstitial fluid. Its low viscosity and elasticity let the epithelium above it ripple with large amplitude over the stiffer ligament and muscle below—the mucosal wave. That mechanical decoupling is what "cover" means in the cover–body theory, and it is why swelling (Reinke's edema) or scarring of this layer so severely disrupts vibration.
Correct Not quite Best answer
The bulk of the fold—roughly 7 to 8 mm—is thyroarytenoid muscle, which is body, not cover. The superficial layer is thin (about 0.5 mm). Cover and body are defined by mechanical behavior, not by size.
Correct Not quite Best answer
This is the picture of recurrent laryngeal nerve paralysis, not superior laryngeal nerve injury. The recurrent laryngeal nerve drives the adductors (lateral cricoarytenoid, interarytenoid) and the thyroarytenoid, so its loss leaves the fold immobile and the glottis leaky. The external branch of the superior laryngeal nerve reaches only the cricothyroid, so adduction is preserved.
Correct Not quite Best answer
The external branch of the superior laryngeal nerve innervates exactly one intrinsic muscle: the cricothyroid, which rocks the thyroid cartilage on the cricoid to lengthen and tense the vocal folds. Without it the folds cannot be elongated, so the upper part of the pitch range is lost while glottal closure—handled by muscles the recurrent laryngeal nerve supplies—remains intact. Conversational speech may sound nearly normal until the voice is pushed higher or used for a long time.
Correct Not quite Best answer
Inability to open the glottis points to loss of the posterior cricoarytenoid—the only abductor—on both sides, which is bilateral recurrent laryngeal nerve paralysis. The posterior cricoarytenoid is not supplied by the superior laryngeal nerve, so a one-sided superior laryngeal nerve injury does not threaten the airway.
Correct Not quite Best answer
That reflex depends on the internal branch of the superior laryngeal nerve, which is sensory to the supraglottic larynx and triggers the laryngeal adductor reflex. The question specifies the external branch, which is motor. Keeping the two branches distinct—internal for sensation, external for the cricothyroid—is the key here.
Want more? The practice section has recall flashcards for this chapter's key terms, plus these questions one at a time.