WHEN YOU SAY "Good morning" at the breakfast table, the mechanical and electrical activity, and the intricate controls required to utter those words - any words - make the functioning of a space vehicle pale in comparison. When you swallow a spoonful of cereal, another series of precisely timed events occurs - whose precision can determine whether you live or die. I'm responsible for these miracles, yet you think of me simply as a short length of reddish garden hose connecting nose and lungs, mouth and stomach. Usually you are aware of me only when I am sore. Let's use a catchall term and call me your throat.
A simple piece of garden hose? Ha! I am a vastly complex transportation system, with elaborate switching devices designed to sort and move assorted cargo: air, fluids, and solids.
I was a finished piece of machinery ready to go to work at the time of your birth. Had I not been, you might well have strangled on your first sip of milk. And it is my eternal vigilance that keeps you functioning normally. Let anything disrupt my timing and you could be in deadly peril. Just try to laugh while swallowing a piece of meat, for instance, and instead of routing it to the stomach, I might let it slip into your windpipe - thus blocking breath. You would collapse from what would look like a heart attack. This so-called "cafe coronary" could kill you unless someone had the quick wit to dislodge the meat. In general, however my behavior is exemplary.
Perhaps the best way to tell my complicated story is to start with my structure. Your neck is a real traffic jam of nerves, blood vessels, vertebrae, other bits and pieces - and my tubes. The first tube is my five-inch-long pharynx - vaguely funnel shaped, the wide portion at the top - which begins behind your nose and ends behind your Adam's apple. Next is the larynx, my main switching point, which routes traffic in correct directions and also serves as the chief component of your speech apparatus. A tapered cylinder about 1 3/4 inches long, roughly bat-shaped when viewed from above, it is an intricate arrangement of nine cartilages, covered with mucous membrane and bound together by ligaments. Part of it protrudes in your neck as your Adam's apple. Next down come two tubes: the esophagus leads to the stomach; the trachea, to the lungs - both about an inch in diameter.
To see how I work, let's watch you swallow a mouthful of food. After it is chewed, your tongue maneuvers it to the back of your mouth. The uvula - that's the little red finger that hangs from the roof of the mouth at the rear - rises and helps shut off passages to the nostrils. (A spoonful of soup might otherwise dribble out of your nose.) Then the tongue humps up, gives a push, and the food is on the way down.
To prevent a cafe coronary every time you swallow, I have a special mechanism. If you touch your Adam's apple and swallow. You will note that it rises. This signals the closing of a flap valve (epiglottis) that sits perfectly over the windpipe. The mouthful slides safely by and into the ten-inch food tube, or esophagus. Richly muscled, the esophagus is able to produce wavelike pushes to finish the job of delivering the food to the stomach.
The food doesn't plop into your stomach directly. You might have rather severe indigestion if it did. As you eat, I open and close a valve like muscle where my esophagus enters your stomach, to pass along food only as fast as the stomach can handle it. If you wolf your food, too much may pile up and temporarily you will have a mildly distressing sense of "fullness." Occasionally, the valve balks and lets acid from the stomach leak upward to attack the delicate membranes of my esophagus. That can mean real discomfort. But hundreds of times a day you will swallow food, drink and saliva with no problems.
How do I manage speech? You think of my vocal cords as violin strings, set vibrating by air from the lungs. Actually, they are more like glistening, whitish lips that open and close as your voice changes pitch, much as your lips do when you whistle. Vocal "folds" would be a more descriptive name. Controlled by an intricate muscular system, the folds open wide to produce deep sounds and narrow to slits for high-pitched sounds. They close tightly when you swallow - that's why he can't talk while swallowing.
Anything - a polyp, tumor, cyst or inflammation - that prevents proper closure of my vocal folds distorts speech. When you yell yourself hoarse at a football game, your vocal folds have become tired, inflamed. The same thing happens to politicians who campaign too vigorously and to singers with too many bookings. My vocal apparatus also reflects emotions. Rage can make you speechless. This paralysis of vocal folds also sometimes hits grammar-school youngsters attempting a graduation address.
In a way my vocal tract-the seven inches from larynx to lips-performs much like a miniature pipe organ. As the column of air from the lungs passes through my vocal folds, the sound resulting depends on the width of the opening and also on how much the tough, fibrous vibrating bands at the edge of the folds stretch. When you go from a grumble to a screech, they stretch nearly a quarter of an inch. (Trained opera singers' bands can stretch nearly half an inch.) What I produce is raw sound, only partially refined into speech. Lips, tongue, nasal tract and palate put on the finishing touches.