Forgive the lousy pun of the title of this column, but the mandible, or lower jaw, has evolved to do many things more vital than opening to let the voice come out, including biting and chewing your food or possibly attacking or fending off an enemy. So, yes, a bad play on words. But the “jaw of singing” is quite different, functionally, from the jaw that is engaged in these life-saving and life-sustaining activities. Let’s look at how the jaw works, considering not so much the disorders of the TMJ (temporomandibular joint), but what it needs to do for free and effortless singing.
You may remember that the larynx can move up and down in the neck, but the elevator muscles are naturally more numerous and stronger than the depressors. A similar imbalance is found with the mandible: the muscles that raise it to chew and to grit your teeth are stronger than those that open the mouth. These lower muscles are always active: even when the jaw is not actively closing, they hold up the mandible against the downward pull of gravity. If all tension were removed from the jaw, we would walk around open mouthed and slack jawed. In fact, normal lower jaw position holds it with the teeth slightly apart with no subjective sense of tension in the muscles.
Considering their size, the muscles that close the jaw and approximate the teeth are some of the most powerful in the body (think of circus acrobats hanging by their teeth from a trapeze). These closing muscles fall into three powerful groups. The temporal muscles fan out on either side of the temple and connect the side of the head with the coronoid process of the mandible, about one inch in front of the TM joint. These work the up-and-down hinge movement of the jaw. The masseters make up the bulge over the angle of the jaw and work at a shorter distance, wrapping around the horizontal body of the mandible. Finally, the pterygoid muscles are along the inside of the jaw in the back and they pull the jaw forward and backward (protract and retract) and side to side as we grind our food. During normal mastication, all of these muscles work in concert tearing, cutting, and grinding our food.
During singing, however, these powerful muscles must yield to the weaker muscles that open the jaw. These attach to the undersurface of the mandible and are intimately related to the floor of the mouth and the tongue, which explains the difficulty some students have in relaxing the tongue while selectively contracting neighboring muscles that control jaw motion and position. During singing, their contraction should be just enough to position the lower jaw in a way that allows the tongue free motion to articulate consonants while being held (without tension!) in a position that allows the tip of the tongue to easily touch the back of the upper frontal incisors.
So, the jaw of singing is fundamentally different from the jaw of biting, chewing, clenching, or teeth grinding. However, since chewing (along with swallowing and other activities) is such a fundamental lower brain function, we may revert to it unconsciously for the wrong reasons at unexpected times.
A common example is bruxism, or tooth grinding. The causes for this behavior are many, including allergies and psychological tension—the jaw is a favorite place to manifest stress. The grinding often occurs at night, the patient unaware except when she wakes up in the morning with a sore, stiff, and difficult-to-open jaw. Apart from the pain and tension in the jaw muscles and damage to the teeth, bruxers generally carry excess tension in their jaw, tension which influences the muscles of the neck and the larynx. The well known neurological phenomenon of “reinforcement” prevails: tension in any muscle causes increased tone and tension in other muscles, both neighboring and distant. It is therefore almost impossible for a clencher and grinder to sing easily with a low larynx and an open throat.
The treatment for such muscle tension can be short term, such as massage, exercises, or physical therapy. Longer term, the cause should be identified and treated. This often involves a nocturnal dental appliance which reduces the powerful tooth-chipping, clenching force developed during bruxism.
There are other causes. Allergies may cause a sensation of chronic itching in the nasopharynx and can result in nocturnal tooth grinding. Moving the jaw, especially protracting it, opens the back of the throat, and some allergic patients will grind at night until they are placed on appropriate allergy treatment.
Patients who preferentially chew on one side may develop asymmetric tension in the jaw. We all have a “favorite” side to chew on, one that has developed either by habit or because perhaps years ago we had a tooth ache on the other side? Often the cause is forgotten but the habit remains. And, rarely, dentists might leave a filling too high and we need to realign our bite to get optimal approximation during chewing. While not as dramatic as bruxism, an asymmetric bite or preferential chewing pattern can also heighten jaw tension, elevate the larynx, raise the floor of the mouth, and impede tongue relaxation and unfettered movement.
It is difficult to overestimate the impact of such asymmetric jaw tension. Years ago, one of my acupuncture teachers pointed out that the side of preferred chewing (and increased jaw tension) typically corresponds with the side on which the leg is shorter, probably due to increased muscle contraction down the entire side of the body. So, for singers, there are also consequences in terms of posture, breathing, and support.
I recently saw a young singer sent to me by his teacher who could not get his throat to relax and his voice to open. On examination, he had a short lingual frenum, or tongue tie. This slip of tissue, which connects the undersurface of the tongue to the floor of the mouth, is usually long enough to allow us, with mouth fully open, to raise the tip of the tongue and touch it against the back of the upper frontal incisors.
The condition is not uncommon in kids. In most cases, the diagnosis is obvious—children have clear articulation problems in speech. In cases of a short frenum, also called ankyloglossia or “tongue tie,” the tethering tissue can be snipped to free the tongue—a minor procedure often done in young children, usually at the suggestion of speech therapists.
But some less severe cases slip through. These patients (now adults) learn to speak by partially elevating their lower jaw, bringing it closer to the upper jaw to allow their tethered tongue tip to reach up. They speak with jaws held rigidly and only partially open, like a gangster from a 1930’s movie. In this case, my singing patient overcame his restriction by learning to also sing with his jaw partially open. Apart from chronically increased muscle tension, the acoustic effect on oral and pharyngeal resonance was obvious, and the jaw tension increased the level of tension in his adjacent vocal tract muscles.
We occasionally see patients who, for no physical reason, speak with the jaw half-clenched—the so-called Larchmont lockjaw is one example (see http://tiny.cc/54663 for a humorous piece on this), but is also seen in other geographic regions and is usually cultural.
I mentioned earlier that the jaw is a favored site for somaticising stress-induced tension. When we need to do an unpleasant task, suppress an emotional response, or face up to a stressful situation, we are often invited to “grit our teeth” or “bite the bullet,” and then “smile, though your heart is breaking.” This tendency to suppress may be cultural—I have frequently found it in Asian, and especially Korean, singers. And this is not just a personal observation—the commonest Botox indication in Korea is for injection of the masseter muscle at the sides of the jaw, to reduce both tension and bulk.
In all of the above, we have not addressed the long-term effects of increased jaw tension and bruxism on the TMJ (temporomandibular joint) itself. This joint is complex—it not only opens and closes like hinge, but also slides forwards and backwards to accommodate the complex multidirectional movements required for biting and chewing. Once the joint becomes damaged (which may be due to multiple causes), the patient will become aware of a click or grinding sound on moving the jaw and will also often feel pain. With this, the tension in the jaw muscles increases further, and singing with a relaxed jaw, flat tongue, and open throat becomes even more difficult.
How to manage your jaw? I have a few suggestions. First, avoid chewing gum if you can. While this is relaxing and stress relieving for some, it does increase the wear and tear on your jaw, especially if the gum is hard or a large bolus. So, no “jaw breakers”! If nothing else, effortful constant chewing heightens the resting tension in your muscles of mastication.
If you do need something in your mouth (and many deal with the dilemma of a need for oral stimulation balanced with a need to avoid excess food) sucking on a (sugar-free) candy may be better, since the swallowing action, which is vagally mediated, will also help you to relax without the constant grind.
Keep your teeth in good shape. Make sure your occlusion is good, and then consciously try to distribute your food to both sides of your mouth as you chew. Your dentist can help identify asymmetric patterns of wear on your teeth and can also tell you whether you grind your teeth at night.
Treat any head and neck condition that might contribute to jaw tension, such as allergies.
And, finally, gain awareness of where your jaw is and how it feels. Singers in general learn to acquire a higher sense of proprioceptive awareness in the head and neck, and this needs to include your jaw. Where is it? What is the level of tension? Remember, monitoring your jaw includes considering how you handle tension. Yoga, meditation, and possibly therapy are perhaps avenues to consider if you need to deal with emotional stress and have a tendency to somaticise tension by clenching.
