At the front of your foot, you’ll find the toes, and the five long, curved metatarsal bones that they connect to. At the back, the prominent ankle bone (talus) sits atop the large and sturdy heel bone.

But we’re not finished yet. In the middle, you’ll find a strange clump of five irregular, funny-looking bones—the cuboid; the navicular; and the medial, intermediate, and lateral cuneiform bones. If you didn’t know better, you might think you were looking at a small pile of moon rocks, rather than an important part of the human skeleton.

Yet despite its odd appearance and lack of publicity, the midfoot (also known as the Lisfranc complex) performs an extremely important role in your life. The five irregular midfoot bones—alongside the adjoining muscles, ligaments, and other support structures—form the arch of the foot. The midfoot must be strong enough to support your weight, but flexible enough to absorb and cushion the impact of each landing, and “springy” enough to transfer the forces generated by the powerful calf muscles all the way to the front of the foot with every step.