What is the nail shell?

Crust is a flat nail structure on the back of human and ape's fingers (toes), which belongs to connective tissue. Its main component is keratin, which is the product of keratinization of finger (toe) epidermis and plays a role in protecting finger (toe).

The growth rate of nails not only varies from person to person, but also is influenced by age, climate, day and night cycle, menstruation, nutrition, gender and other factors. Baby's nails grow about 0.7 mm per week, and the growth rate will increase with age. In adulthood, their nails can grow by 1 ~ 1.4 mm per week on average, but most people will slow down after the age of 30.

Extended data:

Nail action

Nails are one of the appendages of the skin. Has its specific function. First of all, it has the function of "shield", which can protect the pulp of the distal phalanx from damage, maintain its stability, enhance the sensitivity of finger touch, and assist hands to grasp, hold, pinch and squeeze. The nail bed is rich in blood supply and has the function of regulating peripheral blood supply and body temperature.

Secondly, nails are the focus of hand beauty, and beautiful nails add charm to women. A patient with defective or deformed nails may hide his or her fingers from use because of inferiority even if he or she has a well-functioning finger.

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