The Anatomist - Bill Hayes [60]
Ten
HENRY GRAY CALLED IT THE MENTAL PROCESS.
Modern-day anatomists call it the mental protuberance.
Either way, I call it confusing. What does the bump of bone at the base of the chin have to do with using your mind?
I ask Dr. Topp one day as she passes by our dissecting table, and she answers the question with a visual. “Think of Rodin’s The Thinker,” she says, clearly trying to be helpful, though it seems she’s just adding feathers to my pillow fight.
She then adopts the classic pose of deep thought—chin resting on fist—and the air is immediately clear. Of course. But then—
“Well, that’s not literally why.” She explains that mental actually comes from mentum, the Latin word for “chin,” but by this point, the mnemonic has stuck.
“Now you’ll never forget it.”
I have come to love this quality about Dr. Topp—Kim, as she has said we can call her. She is pro-mnemonics, pro-etymologizing, pro-whatever-it-takes to get you to remember the correct anatomical term, which I consider a very Henry Gray–like trait. He often supplies in his text the derivation or translation of terms as well as memorable visual descriptions. At the same time, though, this makes Kim the polar opposite of Dana, who is anti-mnemonics. Too often students use them as a crutch, as a shortcut that bypasses true understanding, Dana believes. But the two instructors are of one mind when it comes to the end result. If the phrase “Tom, Dick, And Nervous Harry” helps you remember the Tibialis posterior muscle, the flexor Digitorum longus muscle, the posterior tibial Artery, the tibial Nerve, and the flexor Hallucis longus muscle—the anatomical mouthful that converges in the lower leg—that’s fine, but don’t stop there. You have also got to be able to identify these structures in a body, know their function, their point of origin, and so on. As for myself, once learning becomes knowing, mnemonics become superfluous, I have found, and at the end of the day, nothing makes knowing come faster than doing a dissection yourself.
I make the first cut for the four of us, a shallow incision from the top of the forehead down to just below the Adam’s apple. In a sense, this is like the imaginary line drawn down the center of a room that siblings must share—Becky and Jenny have their side, and Rachel and I, ours—but there is no rivalry here. Indeed, we share a bond forged by the intensity of what lies ahead: taking apart the face.
Becky and I wield the scalpels for our teams. We both start at the same place, the skin at the cleft of the chin, and cut in opposite directions. The underlying bone here is the mental process. About an inch below each of the lower canines (the pointiest teeth of the lower jaw) is a tiny hole—the mental foramen—through which passes a tiny nerve, the mental nerve. We burrow for our respective holes. The nerve at each site supplies the lower jaw and lip, and when anesthetized during a dental procedure, for instance, causes localized sensory loss. Becky finds hers first, though I am soon behind. Each looks like a threaded needle, a small white fiber poking through a tiny eye.
The next procedure is more delicate: exposing the facial artery, the major blood vessel supplying the face. Just as Henry Gray describes, “This vessel, both in the neck and on the face, is remarkably tortuous,” though, for the dissector, “torturous” could apply as well. An offshoot of the carotid, the facial artery starts in the neck, curves over the mandible, gives off branches to the lips and nose, then terminates at the inner “canthus” (from the Greek kanthos, meaning the corner of the eye). For Becky and me both, dissecting its winding branches takes considerable time and care. But once finished, what is revealed is far more than the twisting vessels themselves. Her side and my side mirror each other, an unexpected and remarkable display of the body’s inner symmetry.
Next, we go our separate ways. This is the last lab of the course and, for the students, a chance to review areas of difficulty before the final