A callus, or tyloma, on the foot is caused from repeated pressure and friction, leading to the build up of thickened skin. The callus, which maybe hard, dry or cracked, acts to protect the area underneath it. A corn is a built up of callous at a very particular area, mostly at the outside of the little toe or under the metatarsal area (middle part of the foot). The part of the corn that is visible is much bigger than the inside part. Pressure that get at the corn will accumulate to the bottom of the corn and presses on the bone’s skin (periost) .This nerve packed bone skin gets inflamed and that’s what we feel as the pain of a corn.