110. Meniscus, noun. From Greek meniskos, “crescent,” diminutive form of mene, “moon.” In physics, the curved upper surface (either concave or convex) of a liquid in a cylinder, which forms as a result of surface tension between the liquid molecules and those of the container. In optics, a lens with one concave surface and one convex surface. In anatomy, a semilunar piece of cartilage found in several joints of the human body, including the knee.
The pair of menisci—one inner, one outer—that cushion the bones of each knee help to steady the joint as you walk or run. If one is torn, it can cause pain and swelling and make walking difficult or impossible. Amazingly, until the second half of the twentieth century these rubbery crescents were considered vestigial: leftover scraps of embryonic development that served no useful function. If one was torn, it was frequently totally removed (“meniscectomized”). Although this relieved the pain, it left the knee unstable and subject to further injury.
Ready for summer walks, I monitor my body, mapping pains. I have, at thirty-three, much strength—still, opportunities for breakdown seem to multiply each year. But four half moons absorb the shock of every step: fantastic satellites. How fine, these little curves.