Examining the Fingernails When Evaluating Presenting Symptoms in Elderly Patients

Human fingernails, located on the dorsal aspect of the terminal 40% of the distal phalanx of each finger, are complex structures involving 3 different layers: The nail plate (the nail). This is the keratinized structure, which grows throughout life; The nail bed (ventral matrix, sterile matrix). This is the vascular bed that is responsible for nail growth and support. It lies protected between the lunula (the "half moon" seen through the nail) and the hyponychium (the posterior part of the nail bed epithelium); and The eponychium (cuticle). The epidermal layer between the proximal nail fold and the dorsal aspect of the nail plate. The primary purpose of the nail is protection. Abnormalities of the nail are often caused by skin disease and infection (most often fungal) but may also indicate more general medical conditions. This discussion does not address localized trauma or nail infections but offers examples of nail abnormalities that may occur with systemic disease.