Nail (anatomy)

Your nails are hard plates.

They sit on your fingers and toes. They help protect your fingertips.

Nails grow from a part under your skin. This part makes new cells. The new cells push old cells forward. The old cells become flat and hard.

This makes your nails strong. They can help you pick up tiny things. Your nails are also tools for scraping.

Fingernails grow faster than toenails. It takes months to grow back. You should trim them often.

Nails stay healthy with good food. They help keep your hands safe.

Your nails are hard plates on your fingers and toes.

They are made of a tough protein called alpha-keratin. This is the same stuff found in horns and hooves. Nails help protect your fingertips from injury. They also help you pick up small things.

Nails grow from a part under your skin called the matrix. This matrix makes new cells. As new cells are made, they push old cells forward. These old cells become flat and hard. This creates the nail plate, which is the visible part of the nail. The white, moon-shaped part at the base is called the lunula.

Under the nail plate is the nail bed. This is the skin where the nail rests. It has blood vessels that give your nails a pink color. Fingernails grow faster than toenails. It takes about three to six months for fingernails to grow back. Toenails take much longer, between twelve and eighteen months. You should trim your nails often to keep them healthy.

Your nails are more than just hard parts on your fingers. They are protective plates found on the tips of digits. Almost all primates have them, except for marmosets.

These plates are made of a tough protein called alpha-keratin. This same protein makes up the claws, hooves, and horns of many animals. Nails help protect your fingertips and the soft tissues around them. They also help you do delicate tasks, like picking up a tiny splinter.

Nails grow through a step-by-step process. It all starts in the nail matrix, which is active tissue under the skin. This matrix produces new cells. As these new cells are made, they push the older cells forward. These older cells become compressed, flat, and translucent. This creates the hard nail plate you can see. The shape of your fingertip bone even decides if your nail is flat or arched.

There are many specific parts to a nail. The lunula is the small, white, moon-shaped area at the base. It looks white because light reflects where the matrix and nail bed meet. Beneath the nail plate sits the nail bed. This is the skin where the nail rests. It contains blood vessels that give your nails a pink color. The hyponychium, or "quick," is the seal under the free edge. This seal protects the nail bed from germs.

Nails grow at different speeds depending on where they are. Fingernails grow much faster than toenails. On average, fingernails grow at a rate of about one month. It takes three to six months for them to grow back completely. Toenails grow about half as fast as fingernails. It can take twelve to eighteen months for a toenail to regrow.

Interestingly, nails do not actually grow after death. The skin just dries and tightens, making them look longer.

Your nails can tell you a lot about your health. Doctors can look at the nail bed to check how well blood is flowing. If you press the nail and it stays white, it may take time to turn pink again. Changes in color or shape can show if a person is sick. For example, bluish nails might mean a lack of oxygen. You can also see lines or spots caused by diet or injury. Taking care of your nails by trimming them helps keep them strong.

A nail is a protective plate found at the tips of the digits. These digits include your fingers and toes. Almost all primates possess nails, though marmosets are a notable exception.

These plates are composed of a tough, rigid protein known as alpha-keratin. This same polymer is what forms the claws, hooves, and horns of many other vertebrates. Beyond mere protection, nails serve as vital tools for life. They allow for an extended precision grip, which helps humans perform delicate tasks like pulling out a splinter. They also provide counter-pressure against the pulp of the finger. This counter-force increases the sensitivity of the fingertip when touching objects.

The growth of a nail is a continuous biological process. It begins in the nail matrix, also called the matrix unguis or onychostroma. The matrix is the active tissue that generates new cells. As these cells are produced, they move outward from the nail root toward the nail plate. During this movement, the cells harden and become compressed, flat, and translucent. This compression is why the nail plate is see-through. The width and thickness of your nail are determined by the size of your matrix. Meanwhile, the shape of your fingertip bone determines if the plate is flat, arched, or hooked.

Several distinct parts make up the nail unit. The visible hard area is the nail plate, or corpus unguis. At the base of the nail, you may see the lunula. This is the whitish, crescent-shaped area often called the "small moon." The lunula appears white because light reflects where the matrix and nail bed meet. Beneath the plate lies the nail bed, which is the skin where the nail rests. The nail bed contains nerves, lymph, and blood vessels. These vessels supply nourishment to the entire unit. Because the nail plate is translucent, the capillaries in the nail bed make the nail look pink.

Protective seals are essential to maintaining nail health. The eponychium is a band of living skin cells that extends from the nail wall. It produces the cuticle, which is a layer of dead skin cells that covers the back of the nail plate. While people often remove the cuticle during a manicure, the living eponychium should not be touched. This prevents pain, bleeding, and infection. At the other end of the nail is the hyponychium, or the "quick." This is the epithelium located beneath the free edge. It forms a seal that protects the nail bed from outside elements.

Nail growth rates vary significantly across the body. In humans, fingernails grow much faster than toenails. On average, fingernails grow at a rate of about one month. It takes three to six months for a fingernail to regrow completely. In contrast, toenails grow about half as fast. It can take twelve to eighteen months for a toenail to fully regrow. Growth rates also change based on age, sex, season, diet, and exercise. Interestingly, nails do not actually grow after death. Instead, the skin dehydrates and tightens, which makes the nails appear longer.

Nails can act as indicators for various medical conditions. Healthcare providers sometimes use the nail bed for the capillary refill test. They press the nail to turn it white and then release it. The time it takes for the pink color to return can indicate how well blood is flowing. A delay might suggest a state of shock. Other changes, such as discoloration or unusual shapes, can signal illness. For instance, bluish or purple nail beds might indicate peripheral cyanosis, a sign of oxygen deprivation. Deep horizontal grooves, known as Beau's lines, can result from disease or aging.

Maintaining nail health involves regular care and awareness of the environment. Trimming and filing the nails helps prevent them from becoming rough or snagging on materials. Nails are also more permeable than skin, meaning they can absorb substances. They contain between 7% and 12% water. This allows water, certain lotions, and even some chemicals like bleach to penetrate the nail. Infections can occur due to yeasts or molds, often caused by tight footwear or dirty socks.

By understanding these biological structures, we can better care for these essential tools of the human body.