Anatomy of the nail and its applied aspects

The nail is a versatile tool in human beings and part of one of the most important sensory organs, the digital tip. Its anatomy is complicated and explains the way many nail changes develop. It is made up of 4 epithelial components and perionychial connective tissue, rich in nerves and specialised nerve endings and well equipped with blood vessels. Its full function depends on the digital bone, tendons and ligaments. Although being the ‘toughest’ skin appendage, it is very sensitive to chronic and repeated stress and strain, and the nail alterations resulting from orthopaedic abnormalities are often mistaken for a fungal infection and are difficult to treat. The various anatomical structures of the nail apparatus may jointly or independently alter or be altered by many various mechanical factors that require mechanical intervention, as they are not amenable to drug therapy; this becomes clear when considering the difficulties in the therapy of a mycosis in a malformed nail. This article describes applied aspects of nail anatomy in the form of nail changes seen with anatomical and orthopaedic changes of the distal phalanx, the toes or fingers, and the foot.