We have all seen them, beautiful, envious nails. They come in different sizes and shapes and you have once or twice wondered, why don’t my nails look like that? On many occasions, you have found yourself asking, what are they made of?
Why do they look like that? Why don’t they bleed when we trim them and yet hurt when we hit them? Some people say they are made of dead cells, others say they are made of weak bones. And I’m sure you have wondered the same at some point. So read on to find out…
Nails are made of keratin, a common protein rich in sulfur. This substance is what makes nails hard. It makes up most of the epidermal appendages such as nails, claws, hair, beaks, horns, and feathers. Cells that are made of keratin are referred to as “dead tissues” but they are the toughest biological materials as evidenced by their presence in nails, horns, scales, and claws.
The basic definition of the nail provided on Wikipedia is “a horn-like keratinous envelope covering the tips of the fingers and toes in most primates.”
However, it is important to note that this horn-like substance is present in more than just fingers and toes of most primates. It is also found on horns, beaks, and claws. So yes, we do share a few things with birds, reptiles, and other mammals.
Also, it is important to note that there is more to the nail than just the nail plate; the nail plate is what we put nail polish on. The rest includes the nail matrix, the nail bed, and the grooves found around it.
- Parts of the Nail
The Nail Plate
The nail plate is to be found atop the nail bed and this is the part that’s made of keratin. Even though this section of the nail looks like one continuous or solid piece, scientists say that it is actually composed of over 100 layers of flattened dead cells that come from the nail bed.
Specifically, these layers of dead cells spring from the germinal matrix epithelium of the nail bed. The cutting margin, the part of the nail that we trim off is called the hyponichium or the free edge or distal edge.
Surprisingly, research indicates that this part of the nail is more permeable than the skin, which allows water to pass through. As a matter of fact, your nails absorb more water than your skin does.
The nail plate appears pinkish in color because it has blood capillaries, whose blood supply comes from the radial and digital arteries. These blood capillaries are also responsible for some of the sensations on our nails.
The Nail Bed
This is the part right under the nail plate, and unlike the nail plate, this part is made of living skin. It starts from the distal margin of lunula and has blood capillaries.
Also, the nail bed is where the nerves are located, which are responsible for sensations. It is this part that registers pain when we hit out toe on a table or chair. Below is an accurate figure of nail structure and anatomy
The above image is obtained from the work of Kumar, Sharma, Naveen, & Jalwal (2017) in their research article published in International Journal of Medical and Health Research
The nail bed, on the distal end, contains sweat glands. However, the nail bed has no fat, sebaceous or follicular appendages but demonstrates firm collagenous. Also, the nail bed shows a limited rate of growth, and its keratin cells are not terminally differentiated like those of the skin.
The Nail Matrix
This is the source of the nail plate and is located right under the proximal end of the nail and is also referred to as the root of the finger nail (see figure above).
This part of the nail is basically specialized epithelial structure with basal cells that once differentiated become the spinous cells and eventually into orthokeratotic cells, which make up the nail plate.
Also, the nail matrix is responsible for the creation of almost all the keratinocytes under the nail. Keratinocytes are the cells that produce keratin, the primary element of nails.
Research by Berker (2013) shows that the nail matrix is primarily responsible for the production of the hard keratin (K31) and more than 81% of cells on the nail plate come from the proximal nail matrix.
Also, it is from the nail matrix that melanocytes and melanocyte-containing cells originate. However, this section of the nail lacks a granular layer.
- The Lunula
This part of the nail is often referred to as the half-moon since it appears as a whitish semi-circle at the base of the visible nail. The reason that this section of the nail is white (unlike the other pinkish sections) is because at this point, the nail bed is tightly packed with keratin. Such high amounts of keratin mask the visibility of block capillaries, hence no pinkish color. This part is invisible for the little finger, but is biggest in the thumb.
When a person’s nails have no lunula, they might be suffering from anemia, malnutrition, of limited levels of cellular oxygen. Also, if this part of the nail is pale blue, this may herald diabetes mellitus while azure lunula indicate Wilson’s disease.
This section is also referred to as the eponychium and emerges from the proximal nail bed. It merges to the nail bed, and is the part removed during a manicure. It works in alignment with the proximal nail fold to protect the nail matrix from potential irritants.
Formation of Nails
During fetal development, the nails can be seen as early as during weeks, and is visible simply as a ridge along the fingers and toes. According to Johnson, Sinkler, & Schmieder (2020), the proximal folds of the nail are develop by 14 weeks while the basic nail unit becomes clear by 16 weeks. The researchers point out that at 5 months, the embryo has a well-formed nail plate covering the nail bed.
According to research, the finger tips and nails present an embryologic connection that shifts after birth and continues to evolve throughout a person’s life. Therefore, molecules such as morphogenic proteins may have a critical role in how nails and bone structures in the fingers are formed.
What Does a Healthy Nail Look Like?
According to research, a health nail should be
- hard yet flexible
- have a whitish surface, that is shiny, smooth, and with no splits, pits, or ridges
- it should have the appearance of being translucent that allows the pinkish hue of the nail bed to show.
- It should grow at rate of 2.5-3 mm (1/10 inch) per month
Surprisingly, even when nails look dry, a healthy nail has a water content of between 15-25
percent. Also, flexible nails have more water content than rigid ones.
Why Do We Have Nails?
Have you ever wondered why we have nails? I mean, it’s not like we use them to tear flesh from our prey, unless you count cat-fights.
One of the purpose of nails is to aid grabbing things, surprisingly, if we had no nails it would be impossible to grab and hold onto objects with precision or accuracy. Also, nails serve to protect finger tips from potential injuries. Furthermore, nails exert counter pressure to the flesh of the fingers, which helps to enhance delicate movements of the fingers. Shockingly, without nails, the sensitivity of the fingertips would be limited. Nails provide a counterforce when fingers touch something, hence increased sensitivity.
Quick Facts about Nails
- The nail on your index finger grows faster than that of your pinkie
- Children’s nails grow faster than those of children. The rate of nail growth decrease as we age
- Your nails grow the fastest during summer than in winter and other seasons
- Nails grow faster during the last trimester of pregnancy
- Nails do not grow after death
- The color and shape of your nails can indicate your overall health.
- Genetics, exercise, weather seasons, age, nutrition, and sex affect the overall growth of your nails
Sources Used in this Article
Berker, D. D. (2013). Nail anatomy. Clinics in Dermatology, 31(5), 509-515 https://www.sciencedirect.com/science/article/abs/pii/S0738081X13001351.
Johnson, C., Sinkler, M. A., & Schmieder, G. J. (2020). Anatomy, Shoulder and Upper Limb, Nails. https://www.ncbi.nlm.nih.gov/books/NBK534769/.
Kumar, V., Sharma, S., Naveen, & Jalwal, P. (2017). A Comprehensive Review on Human Nail. International Journal of Medical and Health Research, 3(10), 72-74 Retrieved from http://www.medicalsciencejournal.com/download/621/3-10-28-175.pdf.