The Hyoid Bone: Mechanics of Breath, Voice, and Swallowing

A mainline IV in the carotid artery of my neck delivered antibiotics and fentanyl. The fever was so high. I offered up my soul to God, begging for a reprieve from the heat that must have been coming directly from the fires of hell. High-flow oxygen into my nostrils didn’t work. The full nose and mouth oxygen mask didn’t work. No water. No food. No oxygen saturation — zero. It was time for intubation.  The doctor rolled up on a stool and began threading a tube into my throat. I’d like to say that I was instantly able to breathe again, but that wasn’t true. My lungs were so full of junk from the pneumonia. I was hungry, thirsty, angry. Sleep was elusive in the ICU. Alarm bells rang every time my vital signs started drifting in the wrong direction. People were in and out all day and night. I was fighting for my life, but really, I was just fighting. And then PJ came to visit. PJ had died from lung cancer four years earlier at age 36. He signed a DNR — do not resuscitate — when he arrived in the ICU. After five years of fighting, he knew that his body had lost the battle. Everyone in the room was crying except for him. He was happy to see his family and friends one last time. I had come directly from the airport to give a hospice massage. He was scheduled to be taken off the life-support oxygen but asked for a short delay so that I could comfort him by unclenching his legs and feet, which were crammed at the end of the bed. I sang “Let There Be Peace on Earth,” as I believed God had called him to heaven as a guiding light for us on Earth. PJ was being promoted to a higher being for exhibiting pure courage and kindness in life, but my brother should not have had to watch the lights go out in his child’s eyes.  I was distraught when PJ came to me. He didn’t speak; he just smiled to say everything was going to be fine. He reminded me that courage is much more powerful than anger and fear in the face of seemingly insurmountable trauma.  Keeping watch at my bedside, my son immediately saw a change in my attitude. I could almost feel his supportive hand holding the white fluffy mitten restraints used to keep me from pulling the tube out of my throat. The medical team was there to help me get better. It was my responsibility to embrace their help and allow the healing and the oxygen to return to the lungs. After eight days, the tube was removed. I could breathe on my own, but I could not swallow or talk. How had the intubation changed the mechanics of my being able to say thank you to those who had kept me alive and to simply drink water to quench my deep thirst? Would I ever eat chocolate, a favorite treat, again? Breath When the doctor inserted the tube into my windpipe a week earlier, he needed my help. I had to lift the epiglottis, a flap that goes over the trachea at the top of the windpipe and is meant to keep food and drink from entering the lungs. Exhaling, which releases carbon dioxide as we breathe, lifts that lever while also helping create sound as air passes over the vocal cords situated just below. So I exhale. And the tube is inserted to create an unobstructed path for pumping oxygen into my very congested lungs. But with the restriction of the lever, swallowing and using your voice are also paused. This seemingly small act on my part — exhaling — is part of a much larger performance that takes place every day, all day in a small space in our mouths and throats and is key to our health. Have you ever watched ballet dancers or a cast of acrobats from the front row as they perfectly time leaps, spins, and entrances and exits? The entire production requires fantastic precision, communication, and teamwork in order for, say, a flyer to land, pivot, and elegantly pass behind the curtain, and the backstage crew to set up the stage for the next scene. This is what’s happening in our bodies. And perhaps the unsung hero of this performance is the hyoid bone, in the anterior neck, as its many precise, mechanical movements allow us to breathe, speak, and swallow. Most people haven’t even heard of the hyoid bone (nevermind how to say it!). It’s unique in that while it’s a bone, it has no articulation with other bones — and yet it’s at the center of one of the most central acts of life: breathing. The process of inhaling begins as oxygen enters the body through the nose and mouth and hits the back of the throat or pharynx. The hyoid bone as well as the cartilage in the neck are hollow in the center to keep the pathway open from the point of entry to the windpipe. The trachea, a duct to the lungs, is kept open with rings of cartilage much like those of an exhaust hose for the dryer. Multiple little muscles, tendons, and ligaments connect the soft, free-floating bones in the neck that work as a team to open and close the epiglottis over the trachea. To allow oxygen into the lungs, the lever is open.  Swallowing But what happens when it’s time to eat and drink? The lever is closed when chewing begins,  but the muscles in the tongue send a signal that food has entered and that mechanisms for swallowing should kick into action. The tongue muscles that connect to the hyoid bone move the horseshoe-shaped bone toward the thyroid cartilage, whose top has a shape very similar to that of the hyoid bone. (It’s as if they used to be the same landmass but broke apart to become separate continents.) Muscles and ligaments connect the hyoid bone to the thyroid cartilage — key to swallowing — which has muscles and ligaments that attach to the epiglottis, the flap I was asked to help open during intubation. Something called cricoid cartilage surrounds cervical number 5 (C5), which is at the top of the trachea and the stopping point for the lever. If C5 and the cricoid cartilage are not lined up correctly, the cover may not open or close correctly. If we look at it step by step, it goes: The tongue muscles move the hyoid bone; the hyoid stops at the matching shape of the top of thyroid cartilage to anchor the lever from multiple angles; and the epiglottis drops and stops at C5, to complete the lever placement. Food and drink enter the esophagus. Fluids that are the consistency of water go through the process pretty quickly, so it’s easy to see why drinking too quickly, especially while trying to talk, can force a cough to expel the fluid from the lungs. When the various tissues involved in swallowing are swollen and confused after intubation and don’t sound any coughing alarm, silent aspiration of water into the lungs can happen. For weeks, I could only drink coffee when I was supervised by the speech therapist, or if the coffee was thickened to the consistency of mud.  The hospital food was ground up to keep it from getting caught in the lever to the windpipe. Years ago, when dining with a  friend, she began choking on a jumbo grain of rice. A first aid teacher who was at the next table told me that my attempt at the Heimlich maneuver, or abdominal thrusts, was not strong enough to adequately push air from the lungs to force the lever open to dislodge the rice. Luckily, she was there to show me the correct way to help. And fortunately swallowing is something that our bodies, when healthy, are miraculous enough to handle on their own. Voice Voice is formed when air exits the lungs, crossing over the voice box, or larynx, which is more of a sound studio than just a single thing. Multiple little muscles, tendons, and ligaments move another group of small sections of cartilage to shape the vocal cords. Ask a skilled singer how voice is created, and you will be presented with a dissertation on how to improve the pitch, quality, and strength of tone using facial expressions, position of the tongue, shallow breath, breath from the diaphragm, ways to restrict air through the nasal passages, and other age-old techniques.  The hyoid bone serves as a temporary brace to the tongue in pronouncing hard consonants. The same tongue muscles that start the downward movement of the lever over the windpipe can pull the hyoid into position for muscular tension to create the forced breath needed for “goat” but not “giraffe.” The nerve to the diaphragm, which helps you inhale and exhale, starts its descent through the lungs at cervical number 3, or C3, the same area where the ends of the hyoid bone loosely rest. The phrenic nerve, critical in autonomic, diaphragmatic breathing during sleep, follows the path of the anterior scalene, a stress breather in the front of the neck that lifts the upper ribs in shallow, fast breath as a backup plan to the diaphragm. Suffice to say that the trauma to the vocal cords from the intubation, the trauma of the muscles attaching to the hyoid bone resting at C3, and the trauma to the neck along the path of the phrenic nerve that supports the diaphragm in its effort to push air over the vocal cords can make for a complicated recovery in speech. Did I mention the trauma to the neck from the mainline IV? It took a while, but I can drink coffee and other “thin” liquids unsupervised and eat normal food, including chocolate. I could never sing that well, so I had no expectations there! I can loudly say thank you — to the healthcare professionals, the prayer warriors, and everyone with kind words of support during the long recovery. The hyoid bone is a mechanical marvel in managing breath, swallowing, and engaging voice. Like any other machine, it can be damaged and may need slow, methodical repair, with attention being paid to all aspects of movement in the neck. Time and very precise, intentional manipulation of muscles, tendons, and ligaments can restore the symphony of movement to a sound structure that cohesively performs the many functions that keep us oxygenated, fed, and heard.

Author: Mary Bai of Tibialis, LLC is a Certified Massage Therapist practicing Medical Massage in Redwood City, CA.