Anatomy of the Larynx: A Journey into your Voice Box

Figure 1

The voice box, a spectacular organ…well, depending on the circumstances and your point of view.  Known as the larynx in medical jargon, it’s the organ vital for human communication, and a source of beautiful melodies and rhythms able to tame even the most savage of beasts--think of the late Freddie Mercury of Queen.  On the other hand, it can have the opposite effect--annoy, inflame, and lead to counter-actions from the receivers of its hideous effects.  Case in point: one of my college dormmates sang nightly while showering (let’s call him Earl) and so loud and terrible that a few others recorded his obnoxious warbling, which was then aired by another dormmate (let’s call him Tony), a D.J. at the college radio station.  Earl had his 15 minutes of fame, though the natural response from those listening to the radio was to cover the ears.  Such is the life of the larynx.  Needless to say, Earl never made it to the big-time--he was no Freddie Mercury.

The larynx is located in your neck.  OK, stupid first-start, but I’ll assume nothing since some people believe it’s actually in the mouth or throat and not related to the neck.  So we’ll start with fundamentals.  First of all, take a feel of the front part of your neck.  You’’ll notice a hard lump, known as the Adam’s Apple.  This is part of the larynx known as the thyroid cartilage.  Thyroid means shield, an in this case the thyroid cartilage can be viewed as a folded shield forming most of the front and sides of the larynx.  The uppermost part of the larynx is the hyoid bone, a horseshoe shaped structure that attaches to the thyroid cartilage via the thyrohyoid membrane (thyroid-to-hyoid; see the logic with medical terminology?) and also serves as an attachment for some of the muscles of the tongue. 

By the way, when we mention throat, this is a general term meaning the area behind the tongue and above the larynx.  More specific medical lingo names this the oropharynx, which includes nifty things as the palatine tonsils, the uvula and soft palate, the back wall of the oropharynx and the tongue base (back portion of the tongue).  Check out the post Sore Throat 101: Anatomy and Preliminary Stuff for a more thorough description of this anatomy. 

The upper drawing of Figure 1 at the beginning of this article is a view from above.  This is the type of view we obtain using a laryngeal mirror to look down at the back of the throat, or with a fiberoptic scope through the nose (see Nasopharyngoscopy), or the view an anesthesiologist has when about to intubate a patient (place a breathing tube). 

Figure 2 is a sagittal section of the larynx.  Imagine slicing the neck and larynx vertical down the middle, not unlike filleting a fish down along its spine.   This figure is then a side-view showing various structures as labeled.
Figure 2
 You’ll notice the terms “true” and “false” vocal cords.  The true vocal cords have an underlying ligament and vocalis muscle, both of which serve to change the tension and shape of the true vocal cords.  The true cords are attached at the back (posteriorly) to the arytenoid cartilages.  The arytenoids slide and rotate along the top of the cricoid cartilage, allowing the true cords to properly adduct and abduct.  The false vocal cords are folds of soft tissue without the underlying vocalis muscle and are not attached to the arytenoids, and are not the major components of voice production.  The shallow space between the true and false cords is called the ventricle, and can be a hidden source of tumor.

The true vocal cords and the space between is also called the glottis or glottic airspace.  The structures of the larynx above the glottis is known as the supraglottis, and the structures below up to the first tracheal ring is called the subglottis. 

The larynx serves two functions.  Naturally it creates one’s voice.  This is accomplished mainly when the true vocal cords open and close, or in medical lingo, abduct and adduct.  This allows air to pass through the glottic airspace between the vocal cords to generate sound.  Other muscles within and outside of the larynx are also involved with this process.

The larynx serves two functions.  Naturally it creates one’s voice.  This is accomplished by movement of the true vocal cords.  The true vocal cords move outward and away from one another (abduct in medical lingo) to open the glottic airspace, or move inward towards one another (adduct) to close the glottic space.  Air travels through a partially closed glottic space between the vocal cords to generate sound.  Other muscles within and outside of the larynx are also involved with this process.

The second function is to protect the airway.  The epiglottis is a flap of tissue at the top of the larynx which closes the larynx while swallowing.  More importantly, the true vocal cords adduct (move inward) to close the glottic space, preventing spillage down into the trachea and lungs.  The false vocal cords also do the same. 

The production of the voice and unique vocal qualities arise not simply from adduction and abduction of the true vocal cords.  In fact, if you visualized the vocal cords of different singers, orators or anyone else for that matter, you couldn’t distinguish one from the other based purely on anatomy since they’d virtually look alike.  Voice production involves a complex array of vocal cord movement, use of the neck, chest, oral and oropharyngeal muscles, nasal resonance, proper breathing techniques, to mention just a few components.  It’s all in the way sound waves are shaped as air travels from the lungs, to the trachea, through the larynx and through all the other structures of the throat (oropharynx), mouth and nose and ultimately to the ear of the receiver; merely viewing the larynx in action would give no clue as to the identity of the speaker, whether it be Freddie Mercury or Earl The-Shower-Crooner.  Sorry Earl.

©Randall S. Fong, M.D.