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Your tongue is the multi-tool of the mouth. Vital to speaking, using a straw, and eating, the tongue also houses your taste buds and a defense system to keep you healthy.
The internal muscles of the tongue belong to a unique group of muscles called muscular hydrostats. These muscles do not need bones or rigid structures in order to extend or contract like other muscles do. Rather, muscular hydrostrats use muscle groups running in various directions (front to back, side to side, and top to bottom) to contract or extend. Contracting one muscle group allows another group of muscles to extend.
Another key component of a muscular hydrostat is the principle of incompressibility. In short summary, muscle is mostly water (approximately 76%). Water is generally considered incompressible, meaning water refuses to take on a smaller shape. As a result, when pressure is applied to water, water will change its shape, the size of its footprint, escape from, or even break, the vessel containing it.
Given that the muscles of the tongue are wrapped in layers of tissue, the water within these muscles is essentially trapped. As the muscles of the tongue contract or extend, the shape and size of the tongue changes to compensate for the pressure changes.
This is why when you stick out the tip of your tongue, the sides draw in and narrow, and when you draw your tongue to the back of your mouth, the sides widen and bulge out.
Flexibility and Stability
The base of your tongue is attached to the floor of your mouth. This provides stability and keeps your tongue from falling out of your mouth. If you look in a mirror and raise the tip of your tongue toward the roof of your mouth, you’ll see a thin strip of tissue connecting the underside of your tongue to the floor of your mouth. That’s your frenulum (freh-nyuh-luhm) and its job is to provide additional stability while preserving tongue flexibility.
On the surface of the base of your tongue at the back of your mouth, you’ll find a collection of cells and tissue call the lingual tonsils. Similar to the tonsils you may have had removed as a child, lingual tonsils serve to defend the body from invading germs and bacteria. Tonsils, adenoids, and lingual tonsils all work together to keep you healthy.
The tongue has other duties besides keeping you healthy. In fact, the tongue has six additional roles it performs throughout the day to help you connect and experience the world around you.
Tasting
Starting near the tip of the tongue and moving backward, you’ll find many small bumps increasing in size until you reach the back of the mouth. These are commonly referred to as taste buds and provide our brain with information about the shape, texture, and taste of the food you eat.
Eating
When you eat, the tongue plays a major role in preparing your food to be swallowed. The tongue moves food to your teeth for grinding and chewing, creates pressure on small salivary glands to produce saliva for food moistening, and manipulates chewed food to form a bolus (soft mass, often rounded in appearance) to be swallowed.
Swallowing
As you swallow, the tongue draws back and propels the bolus into the throat. The back of the tongue keeps moving backward to connect with the back wall of the throat. This action generates pressure to push the bolus through your throat and into your esophagus or “food tube.”
Drinking
If you’d like to wash that bite of food down with a drink, you’ll need your tongue. In order to draw liquid into your mouth, your tongue moves upward and backward creating a small space of low air pressure in the front of the mouth. Because air pressure is always trying to be the same pressure everywhere, the pressures inside the mouth and outside the mouth work to become equal. To do this, air pressure outside the mouth will push on the liquid inside the cup, up the straw, and into the mouth to fill the space until the pressure inside and outside of the mouth is equal again.
Sensing
The tip of the tongue is extremely sensitive and for good reason. Designed as a safety mechanism, having a sensitive tongue enables you to detect non-edible objects, such as bone splinters or fish bones, in your mouth as you chew. The heightened sensitivity to touch also alerts you to food pieces still in your mouth after you swallow.
Speaking
To thank the chef for your delicious meal, you’ll need your tongue for speaking. The tongue works in concert with your teeth and lips to shape the sound produced by your vocal folds into the sounds and words you’ve come to recognize as speech. On average, the tongue helps to produce 90 words a minute and can assume 20 different positions for speech.
To get a better sense of just how agile your tongue is, check out this video from University of Southern California's Speech Production and Knowledge Group (SPAN) as they study the movements of the tongue using rtMRI (real-time magnetic resonance imaging). You can watching additional clips from their gallery.
The tongue in your mouth plays a variety of roles throughout the day and greatly impacts how you experience the world. Whether you’re eating, drinking, speaking, or just trying to stay healthy, your tongue and mouth work together as best friends. Or as I like to call them…Taste Buds.
Check back next time as we take a look at the other half of this duo: The Mouth.
"The Tongue: Multi-tool of the Mouth" is part of an ongoing educational series related to voice and swallowing anatomy and function.
Resources:
Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the tongue work? 2011 Dec 19 [Updated 2016 Aug 23]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279407/
CSSTemplatesMarket. (n.d.). The RTMRI gallery. span | the rtMRI gallery. Retrieved October 4, 2021, from https://sail.usc.edu/span/gallery.html.
Kier, W. M., & Smith, K. K. (1985). Tongues, tentacles and trunks: the biomechanics of movement in muscular-hydrostats. Zoological journal of the Linnean Society, 83(4), 307-324.
Kenning, M. (2019, October 17). The tongue. TeachMeAnatomy. Retrieved October 4, 2021, from https://teachmeanatomy.info/head/muscles/tongue/.
Levine, W. S., Torcaso, C. E., & Stone, M. (2005). Controlling the shape of a muscular hydrostat: A tongue or tentacle. In New Directions and Applications in Control Theory (pp. 207-222). Springer, Berlin, Heidelberg.
The rtMRI videos were WAY cool!!