Diseases of the foot generally are not limited, that is they are related to or manifest elsewhere in the body. However, the foot is often the first place some of these diseases or a sign or symptom of others appear. This is because of the foot's distance from the central circulation, the heart and its constant exposure to pressures from the ground and the weight of the body. The foot may look simple but is a complex structure with 26 bones, 33 joints, numerous muscles, nerves and different ligament types. Any part of the foot can be affected. Some foot disorders may present with just a mild ache, but other foot disorders can be very serious and limit ability to walk or bear weight. Most minor cases of foot pain respond to home care treatments except when severe pain is present as it is a disabling condition and usually needs some type of medical attention. If foot pain is not treated in time, it can lead to long term disability and continuing damage to the foot. Causes The most common cause of foot pain is wearing ill fitting shoes. Women often wear tight shoes that are narrow and constrictive, and thus are most prone to foot problems. Tight shoes often cause overcrowding of toes and result in a variety of structural defects. The next most common cause of foot disease is overuse or traumatic injuries. Diagnosis Besides a physical examination, an x-ray MRI or an ultrasound study may be obtained to assess the soft tissues and blood vessels. Standardized questionnaires and scoring systems, like the American Orthopaedic Foot & Ankle Society (AOFAS) foot and ankle questionnaires, can help elicit the history and physical exam necessary to make and accurate diagnosis of foot and ankle conditions. Skin and nails Often there is a distinction made between conditions of the dorsal skin and plantar skin. Common examples include callus thickened skin, fungal infections of the skin (athlete's foot) or nails (onychomycosis), viral infection of verrucae, and ingrowing toenails that may cause bacterial nail infections (paronychia). Corns and calluses are chunky tough layers of skin that develop on the foot to protect underlying skin from pressure and friction. Corns and calluses are very common and do not look pleasant. Corns and calluses generally need treatment only if they cause problems. For most people, the best treatment of corns and calluses is to eliminate