Overview
The nail is a cornification product of the epidermis, the uppermost layer of the skin. The curved and approximately 0.5-mm-thick nail plate of the fingernails and toenails rests on the nail bed, which is bounded laterally and proximally by the nail wall, a fold of skin. The nail bed is covered by epithelium (stratum basale, spinosum) and lies on the dermis (leather skin). The nail arises from the nail root and is formed by specialized keratinocytes of the nail matrix. It slides forward on the nail bed. Nails consist of dense and glued horny scales. Their main component is hard keratin, a water-insoluble and stable fibrous and structural protein. The proximal whitish area is called the lunula. It is partially covered by the eponychium, the epithelial cuticle. Nails have an important protective and communicative function and enable the grasping of small objects and scratching.
Diseases of the nails
Typical diseases and changes of the nails include, for example (selection):
- Nail fungus
- Nail psoriasis
- Torn nails
- Brittle nails
- Soft nails
- Circulation
- Ingrown nail
- Nail biting
- Discolored nails, e.g. browning of the nails.
- White spots on the nails
- Longitudinal and transverse grooves
- Injuries, bleeding under the nail, pinched nail, loss of the nail.
- Growth disorders
- Aging
