What are corns?

Answer 1

Corns (also called clavi) are specially-shaped calluses of dead skin that usually occur on thin or glabrous (hairless and smooth) skin surfaces, especially on the top of toes or fingers. They can sometimes occur on the thicker palmar or plantar skin surfaces. Corns form when the pressure point against the skin traces an elliptical or semi-elliptical path. The center of which is at the point of pressure, gradually widening. If there is constant stimulation of the tissues producing the corns, even after the corn is removed or the pressure surgically removed, the skin may continue to grow as a corn. The name callum comes from its appearance under the microscope. The hard part at the center of the corn resembles a barley hare, that is, a funnel with a broad raised top and a pointed bottom. "Corn" used to be a generic term for grain, and the name stuck. The scientific name is heloma. Hard corns are called heloma durum, while soft corns are called heloma molle. The place of occurrence differentiates between soft and hard corns. Hard corns occur on dry, flat surfaces of skin. Soft corns (frequently found between two toes) stay moist, keeping the surrounding skin soft. The corn's center is not soft, however.1

1. http://en.wikipedia.org/wiki/Callus