The Anatomist - Bill Hayes [28]
“Can anyone identify the root of the tongue?” Dana asks from the distance.
I move down to the mouth area and see what looks like a gargantuan mushroom rooted in the lower jaw. Laura uses a metal probe to point at the base of this mass, and Dana nods.
A tongue in profile does not remotely resemble the one you see in your bathroom mirror; it is far thicker and longer than you would ever expect. Beyond the pebbly portion at the back of the mouth, there is a full third you never see, which curves down into the pharynx, the top of the throat. The tongue is composed of hundreds of taste buds and eight different muscles and is animated by a major cranial nerve. Best known as the organ of taste, the tongue is also a natural contortionist, able to roll and fold, in many cases, and to wag and probe, making it ideally suited for its supporting roles in chewing, mouth cleaning, speaking, and swallowing.
The act of swallowing had taken up a good deal of Dana’s earlier classroom lecture. Sitting in the lecture hall, I had tried to record every detail as she spoke, but this was like trying to notate the choreography of a dance while watching it for the first time. I finally set my pen down and tried a new tack, swallowing while I listened and listening while I swallowed, trying to feel each step Dana described. Still, I could not quite visualize a gulp from start to finish.
But with the hemihead to illustrate, I can now see how the various parts all come into play, how, in order to swallow something—say, a pill—the tip of your tongue first presses up against the roof of your mouth, nudging the pill backward. Next, the back of the tongue rises up to force the pill to the back of the mouth. This automatically stimulates nerves that send your soft palate (the fleshy parts at the back roof of the mouth) upward, sealing off the nasal passageway. Now the pill and the water you are swallowing it with won’t shoot out your nose. But in order for it to go down your throat, a number of complicated maneuvers still have to occur. As the hemihead shows, the pharynx is a common pathway for both air and food, but the epiglottis, just below the far curve of the tongue, closes off the opening into the windpipe so the pill does not head to the lungs. At virtually the same time, the voice box moves up and the muscles of the pharynx contract, pushing the pill past the epiglottis and—gulp—into the esophagus, the muscular tube feeding into the stomach.
By the time the imaginary pill drops into my hypothetical abdomen, a very real but unexpected transformation has taken place: the hemihead has lost much of its gruesomeness—so much so that, when Dana proposes, “Okay, now let’s talk about the gag reflex,” I think it a fine idea. Which is not to say I suddenly find it pleasant to look at. But, by comparison with our adventures in the abdominal cavity, the hemihead is neat and clean, practically free of fat, and looks carefully packaged. Each part has its own tidy little chamber. It is hard to imagine how a headache could ever fit in there.
After Dana leaves to work with another group, we make our way through all twenty-eight items on the lab list, from the sphenoid sinus (the deepest part of the nasal cavity) to the dangling uvula to the vocal cords. Before going home for the day, though, we have one last bit of business: returning the hemihead to its container. I offer to take care of this while Massoud and the others agree to clean the instruments and rewrap the cadaver.
I gently lift the specimen with both hands. It is heavy, which surprises me. A typical human head weighs about twelve pounds; this feels closer to a twenty-pound dumbbell. To protect the hemihead for storage, I need to bundle it in gauze, but first I turn it just enough so that I can look at the face. A pale bushy eyebrow perches above the closed eye. The nose must have been