To start at the beginning, our gradual evolution to a bipedal posture created complex and difficult extra functions for our feet. On top of weight bearing now on only two points, the complexity of constantly balancing our entire body while also performing the myriad movements necessary for walking, running, playing. Even basic standing is impressive work. The strength, flexibility, and constant adjustments required to perform all of this is extraordinary.
Contrary to what we may think, our feet do not simply rest flat on the ground. The structural arrangement of all of these bones, ligaments, and tendons that have developed to support all of this work has resulted in three arches, which are crucial in giving the feet their required flexibility, shock absorbing ability, and weight distribution capacity. When we are simply standing, the weight of the body is essentially distributed among three points in each foot:
- The posterior inferior tuberosity of calcaneus (heel bone) receives most of the weight.
- The secondary weight bearing point is the head of the first metatarsal, a comparatively large bone, relative to the other bones in the foot. This is what we’d recognize as the largest part of the ball of our foot.
- The third point, which supports the last of the weight, is the head of the fifth metatarsal, which is the outer, opposite side of the ball of our foot from the first metatarsal.
Take a second and stand on one foot, then pay attention to the way your foot unconsciously and automatically redistributes your weight among these three points. You’ll appreciate how quickly and constantly the body is making mechanical adjustments in the feet in order to maintain your balance.