Corns, like calluses, develop from an accumulation of dead skin cells on the foot, forming thick, hardened areas. They can develop due to bone pressure against the skin, and are common on the tops and sides of the toes and on the balls of the feet. Corns can be hard and dry or soft and mushy. Common causes of corns are boney prominence, sometimes due to arthritis, or poorly-fitting shoes.They contain a cone-shaped core with a point that can press on a nerve below, causing pain. Corns can become inflamed due to constant friction and pressure from footwear. Corns that form between the toes are sometimes referred to as soft corns.
Think of a balloon. If you push on it, it expands; your heel does the same. If it is encased in a callus, it can't expand, so it splits. Heel fissures can certainly be unsightly enough to make you want to enclose your feet in closed shoes instead of sandals, but the issue of cracked heels is more than a cosmetic consideration. Cracks in dry skin, such as heel fissures are also painful enough to interfere with exercise and even with the ordinary needs of life as they can make walking uncomfortable enough to be difficult. Moreover, over time heel fissures that remain untreated can worsen, splitting open more and more, getting both wider and deeper. In the worst case scenario, a heel fissure can begin to reveal underlying tissue, even exposing it to infectious agents if the fissure begins to bleed.