Fingernails are small plates on the tips of the fingers or toes. They are made of keratin and perform different functions. Diseases or abnormalities of the fingernails may provide information about certain diseases of the associated body.
What are fingernails?
Schematic diagram showing the anatomy and structure of fingernails. Click to enlarge. Fingernails are the curved plates at the tip of the fingers or toes of primates (and therefore humans). They are located at the top of the finger or foot tip and are slightly translucent. Consisting of keratin, a water-insoluble horny substance, fingernails perform several functions in everyday life. They continue to grow unceasingly throughout life and thus need to be trimmed regularly. In many cultures, they are specially groomed or designed or decorated, for example, to express prosperity. Fingernails can show various diseases or also abnormalities, which not infrequently also indicate an existing underlying disease of the affected person. It is therefore not only worthwhile for the attending physician to take a look at the fingernails and their condition.
Anatomy and structure
Primate fingernails are horny plates on the upper tip of the fingers or toes, formed from the epidermis (cuticle). They consist of up to 150 layers of horn cells and are about 0.75 mm thick in adults. On average, they grow between 0.5 and 1.2 mm per week. The rate of growth decreases with age. At the end of each fingernail is the nail pocket. Under the nail itself is the nail bed, which consists of connective tissue. On the sides, the fingernail is surrounded by the so-called nail wall, also called nail fold, which also covers the non-visible parts of the same. This layer of skin gives the nail support and at the same time provides protection against tearing. The fingernail itself does not have any sensory or nerve cells.
Function and tasks
Fingernails perform different tasks in primates. On the one hand, they serve as protection and can be used as a weapon, for example, to defend against attackers. In humans, of course, this purpose is used comparatively rarely. Here, the fingernails play a decisive role in the grasping function, because they support the so-called finger berries. These are tactile pads on the inside of each fingertip. They are very well supplied with blood and have a large number of nerve cells. A large part of the touching or feeling takes place over this important area of the finger. The fingernails are now, on the one hand, a kind of abutment for the fingertips. On the other hand, they are very sensitive, especially in the area of the fingertip skin under the actual nail, because there is a sensory cell fringe there. Touching an object with the fingernail provides information about its hardness and texture, for example. Last but not least, the fingernails are also used in numerous everyday activities and actions. For example, they can be used to pluck, tear or scratch and are thus suitable for opening packages or removing adhesive labels.
Diseases, ailments and disorders
The most common damage to fingernails occurs as a result of trauma caused by injuries or accidents. If the nail bed is affected, the damage usually remains visible forever. If an injury cannot heal and/or the nail root is permanently damaged, the nail will fall out and not grow back. If the fingernails show damage or abnormalities that are not related to trauma, the cause may be nail fungus or vitamin H deficiency, for example. Then, among other things, brittle and splintering nails occur. Psoriasis can also affect the nail and lead to spots. Spots can also appear when certain medications are taken over a long period of time. A hangnail, a stuck piece of skin on the side of the nail, is harmless but can lead to painful inflammation if not removed. Frequent use of aggressive nail polish removers can cause damage to the fingernails. If changes in the nails occur for which no cause is known, it is advisable to consult a doctor and have them clarified.
