Crescent is not as healthy as everyone usually agrees. Healthy nails should be translucent, glossy, tough and not easy to break. They can show the light pink color of the nail bed under the nails. It's not so scientific to say that crescent moon reflects physique.
We usually say that the crescent, known as nail half moon or half moon mark, is a natural phenomenon in the process of nail growth.
How is crescent formed?
The part of the nail that grows under the skin is called methyl, and the root of the nail is also in this range. The newly produced keratinocytes are still fresh, round and white. These new cells push the previous generation outward. As they push their way up to the base of the nail, the cells of the previous generation are squashed and flattened, dying and hardening at the same time. When the previous generation of cells entered the visible part of the nail, most of the keratin cells had been 'squeezed' to fade white and become translucent, and had become as hard as a small shield.
Because the growth rate of methyl decreases from the center to both sides, and the time required for keratinocytes to become translucent does not change due to the different positions, thus forming the arc of white and translucent junction. If the white arc just shows up, it's the half moon of armour, which is what we call the crescent moon.
That is to say, the crescent is just a fingernail without full horniness.
If the nail growth rate is slow, or the methyl group is relatively backward, then it is normal to not see the crescent. That is to say, there are only invisible crescent and no non-existent crescent.
Similarly, if the nail wears fast, it grows naturally, such as the thumb. Therefore, the crescent is easy to be pushed out. This explains that most people's thumbs have crescent teeth because of the high frequency of thumb use. Compared with the other four fingers, the little finger is less labor loving, so the growth speed of the little finger nail is slower than the other four fingers. Therefore, the crescent of little finger is rare.
But there are exceptions to everything. Because those who often play the piano and violin use their little fingers more frequently than ordinary people, and their fingernails grow faster, so the crescent will also appear. Some people's nails are born to grow fast, so the little finger will also have crescent.
Of course, although crescent is not a strong evidence of physical health, sometimes some changes of crescent can also reflect some health problems:
If in a short period of time, you suddenly have a lot of full moon teeth from no moon teeth, or your full moon teeth suddenly become invisible, maybe there is a thyroid problem. Hyperthyroidism, the body's metabolism will become rapid, including the growth of nails.
As a result, there will be a lot of keratin that is a little hard but not yet translucent. In this way, people without crescent will have full crescent, and people with crescent will become larger and larger.
If it is hypothyroidism, on the contrary, the metabolism of the whole body becomes very slow, and the growth of nails slows down or even tends to stop. If the keratin is mature and there is no new one to supplement, the crescent naturally becomes smaller and smaller until it disappears.
When suffering from serious illness or malnutrition, methyl can't get enough nutrition to make keratin cells, which may also make crescent teeth disappear. In addition, with the growth of age, the body's metabolism is becoming slower and slower, and the crescent teeth are also a little smaller than when you were young.