The Secrets Inside Us

Illustration: Luca Zamoc
Illustration: Luca Zamoc

(Originally published in the NY Times)

WHEN the news broke recently that a team of Belgian scientists had “discovered” a new body part — a ligament located just outside the knee — the first place my mind went was to Padua.

Padua is the small city in northern Italy where the 16th-century Brussels-born scientist Andreas Vesalius taught anatomy and created his history-making masterpiece, “De Humani Corporis Fabrica” (“On the Fabric of the Human Body”), published in 1543. The old man would have been delighted by the news, I couldn’t help thinking.

Vesalius’s wasn’t the first book on anatomy, but it was the first detailed study based entirely on actual dissection of human cadavers — on scientific fact, not supposition. It systematically dismantled the error-filled doctrine of Galenism, which rested in part on animal rather than human anatomy and had held sway for 14 centuries. But in mapping the inner body, Vesalius didn’t get everything right.

He didn’t correctly grasp the circulation of the blood, a discovery that the English physician William Harvey made in the 17th century — nor was his work immediately embraced by all. Revered in retrospect, he was not immune to criticism, or skepticism, in his day.

May his fellow scientists in Belgium take this to heart.

Reactions to their announcement, published in The Journal of Anatomy, cycled quickly from excitement to heated debate and criticism.

Had the scientists discovered this ligament, or merely described it? Had they done anything more than confirm what earlier scientists had intimated? How could a ligament possibly have gone unnoticed all this time in any case? Some smelled a conspiracy: Was this just a ruse to create yet another opportunity for unneeded and expensive knee surgeries?

Graphics accompanying news articles made the so-called discovery seem all the more absurd: The anterolateral ligament (A.L.L., for short, as they named it), which is one of a number of ligaments binding the femur to the tibia at the knee, looked in illustrations as obvious as the nose on one’s face. Vesalius we could forgive — he didn’t have access to M.R.I.s, X-rays, or countless cadavers — but how could modern anatomists, orthopedists, physical therapists and personal trainers have missed such a vital part?

This is where I wanted to raise my hand.

A few years ago, I had the privilege of participating in anatomical dissections alongside medical students, and let me tell you: Open up a human body, and you will be very surprised by what you see. Nothing is as perfectly clean and clear as anatomical illustrations suggest. The body is murky. Muscles don’t neatly separate for you in order to display their various parts. What lies beneath the chiseled beauty that is a six-pack, to cite one example, is wet and messy.

The precise point where a tendon turns to muscle, and ligament attaches to bone, isn’t always obvious. Parts are closely bound together in a body (indeed, “ligament” comes from the Latin for “to bind”), packed in tight and padded within clumps of protective fat, or bunched together with fascia, the corporeal equivalent of cellophane. You have to dig around to find what you’re looking for, and know what it is you are looking for.

We were encouraged not only to study our “own” cadaver, but to go from one to another, to another, to compare. “You’re always going to find variation,” I remember one of my anatomy professors telling me. “Everyone’s got the same parts, essentially, but they’re put together in different ways.”

What’s more, aging, injury, disease and scarring change things internally. Even that most recognizable of anatomical parts, the human heart, does not look the same in every body. Yes, the poets were right: Everyone’s heart really is different.

These variations aren’t always obvious. When it comes to soft tissue like muscle, tendons and ligaments, we may be talking about differences measured in millimeters. And this is one point — an important point — that the Belgian scientists were making with their study of the A.L.L.

As they acknowledged, the French surgeon Paul Segond first described this “pearly, resistant, fibrous band” at the knee joint in an 1879 paper, and other, more precise descriptions followed. But there had been lingering ambiguity as to whether it was part of an adjacent ligament — almost like a freeway offshoot — or a distinct ligament with a specific role in stabilizing the knee.

And this is what their paper tried to answer. A close analysis of 41 dissected cadavers found that the A.L.L. was, indeed, a ligament that consistently appeared in the same place, originated and inserted at the same spots and measured approximately the same length in all of the bodies studied.

Whether this is the answer, the final answer, remains open to debate. Continuing studies will further clarify the ligament’s biomechanical function, and whether there are clinical implications.

Meanwhile, the rest of us can be our own Vesalius and discover this newly, precisely described body part on our own: Put a hand to the outside of one knee, right at the ledge of the shallow pit next to your kneecap. Extend, bend, stand, crouch, twist. All the while, picture this: right beneath your fingers is a pearly piece of tissue, about an inch-and-a-half long, helping to make all of this happen.

Now, take a step. Take a moment. Appreciate it.

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