Nail Anatomy

Structure, Function & Growth

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Nails serve two important purposes: they serve as protective plates and they enhance the sensation of the fingertips and toes. Our fingers and toes contain nerve endings that allow us to process the volumes of information we receive every time we touch something. Furthermore, the nail acts as a counterforce, providing even more sensory input when we touch an object.

Nail Growth

Our nails are constantly growing, but the growth rate slows down due to poor circulation and with age.

Fingernails grow faster than toenails at a rate of 3 millimeters per month. It takes 6 months for a fingernail to grow from the root to the free edge. Toenails grow much slower, at just 1 millimeter per month. It takes a toenail 12 to 18 months to grow from root to tip.

Nail Structure

The structure of the nail is divided into six parts: the root, nail bed, nail plate, eponychium, paronychium, and hyponychium. Each of these six components has a specific function, and if a component is disrupted it can result in the abnormal appearance of the nail.

  • Nail Root: The root of the fingernail is also known as the germinal matrix. Its edge appears as a white crescent, known as the lunula. The root portion of the nail lies below the skin, underneath the fingernail, and it extends several millimeters into the finger. It produces most of the volume of the nail and the nail bed.
  • Nail Bed: The nail bed is also referred to as the sterile matrix. It extends from the edge of the nail root, or lunula, to the hyponychium. The nail bed contains blood vessels, nerves, and melanocytes that produce melanin. As the root grows the nail, the nail streams down along the nail bed and adds material to the underside of the nail to make it thicker. When the nail grows properly, the nail bed is smooth, but if it doesn't grow correctly, the nail may split or develop ridges that aren't cosmetically attractive.
  • Nail Plate: The nail plate is the actual fingernail, and it's made of translucent keratin. The pinkish appearance of the nail comes from the blood vessels underneath it. The underside of the nail plate has grooves that run along the length of the nail and help anchor it to the nail bed.
  • Eponychium: The eponychium is more commonly known as the cuticle. The cuticle is situated between the skin of the finger and the nail plate. It fuses these structures together and provides a waterproof barrier.
  • Perionychium: The paronychium is the skin that overlaps onto the sides of the nail plate, also known as the paronychial edge. The paronychium is the site of hangnails, ingrown nails, and paronychia, a skin infection.
  • Hyponychium: The hyponychium is the area between the nail plate and the fingertip. It is the junction between the free edge of the nail and the skin of the fingertip. It also provides a waterproof barrier.

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