The upper part of the foot has sometimes been named the “saddle” as it is believed to look like the back of the horse where the saddle might be placed. You can see a distinct deformity or bump that could develop on the top of the feet, which is why this is sometimes termed a Saddle Bone. https://fitofithealth.com/saddle-bone-deformity-throw-the-kitchen-sink-at-it/