1. Nail Structure & Growth
Chapter 9
Nail Structure & Growth 1

2. Learning Objectives
Describe the characteristics of normal, healthy nails.
Describe the nine basic parts of the nail unit.
Discuss how nails grow.
WHY STUDY NAIL STRUCTURE AND GROWTH?
Understanding the structure and growth of natural nails allows you to expertly groom, strengthen, and beautify nails.
It is important to know the difference between the nail cuticle and the eponychium before performing nail services.
Understanding the structure and growth cycles of the natural nail will prepare you for more advanced nail services. 2

3. Introduction
You cannot perform professional nail services without understanding the structure and growth of the natural nail.
Specializing in nail services will add extra revenue to your pocket and give you another way to express your creative talent.
By becoming familiar with the anatomy and physiology of the nail, you will be able to better recognize abnormalities and disorders that can and cannot service in a salon.
INTRODUCTION
You probably know that the natural nail has a cuticle. Do you know whether the cuticle is living or dead skin? And do you know where the plate and the bed are located in the natural nail? This chapter gives you the answers to these questions and more.
• You cannot perform professional nail services without understanding the structure and growth of the natural nail.
• Specializing in nail services will add extra revenue to your pocket and give you another way to express your creative talent.
• By becoming familiar with the anatomy and physiology of the nail, you will be able to better recognize abnormalities and disorders that can and cannot service in a salon. 3

4. Distinguish the Structure of the Natural Nail
Onyx – the technical term for natural nail
The onyx is the hard protective plate composed mainly of keratin, the fiber-shaped protein found in skin and hair.
DISTINGUISH THE STRUCTURE OF THE NATURAL NAIL
The keratin in natural nails is harder than the keratin in skin or hair.
The natural nail is located at the end of the finger or toe. It is an appendage of the skin and is part of the integumentary system, which is made up of the skin and its various organs.
Nail plates protect the tips of the fingers and toes, and their appearance can reflect the general health of the body.
(continues) 4

5. Distinguish the Structure of the Natural Nail (continued)
A normal, healthy nail is firm but flexible.
Surface is shiny, smooth, unspotted.
Whitish and translucent in appearance, with the pinkish color of the nail bed below showing through.
Water content is between 15 and 25 percent
DISTINGUISH THE STRUCTURE OF THE NATURAL NAIL (continued)
A healthy nail also is whitish and translucent in appearance, with the pinkish color of the nail bed below showing through.
The water content directly affects the nail’s flexibility.
The lower the water content, the more rigid the nail becomes.
Using an oil-based nail conditioner or nail polish to coat the plate can reduce water loss or prevent excessive absorption and improve flexibility. 5

6. [Insert ICON4 here] 6 LESSON ACTIVITY 1
Ask students to review their own nails now to determine the health and well-being of their nails.
Ask them to answer these questions in a group discussion:
Is the nail firm and yet flexible, or is it rigid and inflexible?
What does the surface of your nail look like?
Does your nail look hydrated, or is it lacking in hydration? 6

7. Identify Nail Anatomy Nail plate (nail body) Eponychium Free edge
Nail bed
Matrix
Lunula
Cuticle
Eponychium
Perionychium
Hyponychium
Specialized ligaments
Nail folds
Sidewall
IDENTIFY NAIL ANATOMY
The natural nail unit is composed of several major parts, including the:
Nail plate
Nail bed
Matrix
Cuticle
Eponychium
Perionychium
Hyponychium
Specialized ligaments
Nail folds
(continues) 7

8. Identify Nail Anatomy (continued)8

9. Nail Plate The most visible and functional part of the nail unit
Rests on/slides across nail bed
Formed by matrix cells
Constructed in layers
Free edge extends over tips of finger or toe
NAIL PLATE
The nail plate is a hardened keratin plate that sits on and covers the nail bed.
It is the most visible and functional part of the nail unit.
The nail plate is relatively porous and will allow water to pass through it much more easily than through normal skin of equal thickness.
As it grows, the nail plate slowly slides across the nail bed.
The nail plate is formed by the matrix cells. The sole job of the matrix cells is to create nail plate cells.
The nail plate may appear to be one solid piece, but is actually constructed of about 100 layers of nail cells.
The free edge is the part of the nail plate that extends over the tip of the finger or toe. 9

10. Nail Bed Skin supporting nail plate as it grows toward free edge
Extends from lunula to just before free edge
Attached to nail plate by a thin layer of tissue called bed epithelium
Supplied with many blood vessels
NAIL BED
The nail bed is the portion of living skin that supports the nail plate as it grows toward the free edge.
Because it is richly supplied with blood vessels, the nail bed has a pinkish appearance from the lunula to the area just before the free edge of the nail.
The nail bed contains many nerves, and is attached to the nail plate by a thin layer of tissue called the bed epithelium.
The bed epithelium helps guide the nail plate along the nail bed as it grows.
As a professional, you should understand the difference and use the proper names for the parts of the nail unit—for example, nail polish is applied to the nail “plate,” not the nail “bed.” 10

11. Matrix Where nail plate cells are formed
Composed of matrix cells that produce nail plate
Contains nerves, lymph, and blood vessels to nourish nails
Extends from under nail fold at base of nail plate
MATRIX
The matrix is the area where the nail plate cells are formed.
It is composed of matrix cells that produce the nail plate cells.
The matrix area contains nerves, lymph, and blood vessels to nourish the matrix cells. As long as it is nourished and healthy, the matrix will continue to create new nail plate cells.
The matrix extends from under the nail fold at the base of the nail plate.
Growth and appearance of the nails can be affected if an individual is in poor health, if a nail disorder or disease is present, or if there has been an injury to the matrix. 11

12. Lunula Visible part of matrix Whitish, half-moon shape at base of nail
Color caused by reflection of light off matrix surface
Some are hidden under eponychium
LUNULA
The lunula is the visible part of the matrix that extends from underneath the living skin.
It is the whitish, half-moon shape underneath the base of the nail.
The whitish color is caused by the reflection of light off the surface of the visible part of the underlying matrix. The lighter color of the lunula shows the true color of the matrix.
Every nail has a lunula, but some lunulas are short and remain hidden under the eponychium. 12

13. Cuticle
Dead, colorless tissue attached to nail plate from underside of skin that lies above natural nail plate
Sticks tight to the nail plate; difficult to remove from nail plate
Seals the space between the natural nail plate and living skin above to prevent entry of foreign material and microorganisms
CUTICLE
The cuticle is the dead, colorless tissue attached to the natural nail plate.
The cuticle comes from the underside of the skin that lies above the natural nail plate.
This tissue sticks tight to the nail plate and is difficult to remove.
Its job is to seal the space between the natural nail plate and living skin above (the eponychium) to prevent entry of foreign material and microorganisms and to help avoid injury and infection. 13

14. Eponychium The living skin at base of nail plate covering matrix
Often mistaken for cuticle
Cannot be trimmed or cut by nail technician
EPONYCHIUM
The eponychium is the living skin at the base of the natural nail plate covering the matrix area.
The eponychium is often mistaken for the cuticle. They are not the same.
The cuticle is the dead tissue adhered to the nail plate; the eponychium is living tissue that grows up to the nail plate.
The cuticle comes from the underside of this area where it completely detaches from the eponychium and strongly attaches to the new growth of nail plate.
It pulls free to form a seal between the natural nail plate and the eponychium. 14

15. [insert ICON4 here] 15 LESSON ACTIVITY 2
Assign students to work in pairs and review the FYI checklist in the textbook regarding the differences between cuticle and eponychium. Have them examine each other’s nails and identify which part of the nail structure is cuticle and which part is eponychium. Have them report their findings to the full class and discuss their questions. 15

16. Perionychium
The living skin bordering the root and sides of a fingernail or toenail
PERIONYCHIUM
The living skin bordering the root and sides of a fingernail or toenail 16

17. Hyponychium
The slightly thickened skin that lies between the fingertip and the free edge
Protective barrier that seals the free edge, preventing microorganisms from invading and infecting the nail bed
HYPONYCHIUM
The hyponychium is the slightly thickened layer of skin under the nail that lies between the fingertip and the free edge of the nail plate.
It forms a protective barrier that prevents microorganisms from invading and infecting the nail bed. 17

18. Specialized Ligaments
Tough bands of fibrous tissue that connect bones or hold an organ in place
Attach the nail bed and matrix bed to underlying bone
Located at base of matrix and around edges of nail bed
SPECIALIZED LIGAMENTS
A ligament is a tough band of fibrous tissue that connects bones or holds an organ in place.
Specialized ligaments attach the nail bed and matrix bed to the underlying bone.
These ligaments are located at the base of the matrix and around the edges of the nail bed. 18

19. Nail Folds Folds of normal skin surrounding nail plate
Form nail grooves or furrow on each side of the nail
NAIL FOLDS
Folds of normal skin surrounding nail plate
Form nail grooves or furrow on each side of the nail 19

20. Sidewall Also known as the lateral nail fold
The fold of skin overlapping the side of the nail
SIDEWALL
Also known as the lateral nail fold
The fold of skin overlapping the side of the nail 20

21. Discuss Nail Growth
Growth is affected by nutrition, general health, and exercise.
Nails grow forward, starting at matrix and extending over fingertip.
Nails grow in a variety of shapes.
Average growth is 1/8 to 1/10 of an inch per month.
Growth is faster in summer than winter.
Children’s nails grow faster than adults’ nails.
DISCUSS NAIL GROWTH
A normal nail grows forward from the matrix and extends over the tip of the finger.
Normal, healthy nails can grow in a variety of shapes, depending on the shape of the matrix.
The length, width, and curvature of the matrix determine the thickness, width, and curvature of the natural nail plate.
(continues) 21

22. Discuss Nail Growth (continued)
Middle fingernail grows fastest.
Thumbnail grows slowest.
Toenails grow slower than fingernails.
Nails are not shed automatically like hair is. 22

23. Nail Malformation
This can be a temporary or permanent condition caused by disease, injury, or infection that has affected the matrix.
The shape or thickness of the nail plate can appear altered or deformed.
Nail malformation can cause a person to shed a nail.
Replacement of a natural fingernail takes 4 to 6 months.
Replacement of a toenail takes 9 to 12 months.
NAIL MALFORMATION
If the nail is abnormal in shape or form it is called nail malformation.
This can be a temporary or permanent condition caused by disease, injury, or infection that has affected the matrix.
In this case, it can change the shape or thickness of the nail plate and can appear altered or deformed.
In fact, these conditions are generally the only reason a person will shed a nail. 23

24. Aging
As a person ages, parts of the nail matrix begin to permanently slow down production, causing the plate to develop a series of narrow grooves running down the length of the plate.
AGING
As a person ages, parts of the nail matrix begin to permanently slow down production, causing the plate to develop a series of narrow grooves running down the length of the plate. 24

25. [INSERT ICON4 HERE] 25 LESSON ACTIVITY 3
Ask students to think back to the last nail malformation they noticed either on their own hands or on the hands of someone else.
Ask them to write down a description of the malformation and to use the information in the chapter to determine the cause of the malformation. 25

26. Know Your Nails
Many cosmetologists are interested in nails because of the creative opportunities they present.
As with every other area of cosmetology, this creativity must be grounded in a full awareness of the structure and physiology of the nails and the surrounding tissue.
KNOW YOUR NAILS
Working on strong, healthy nails can be a pleasure.
Remember that as a licensed cosmetologist, you are allowed to work only on healthy nails and skin with no visible signs of disease or infection. 26

27. Summary and Review
Well-manicured nails, whether natural or artificially applied, have always been recognized as an indication of good grooming; nails originate in the epidermal layer of the skin and, like hair, their condition is dependent upon the individual’s overall health.
A balanced diet filled with the daily required vitamins and nutrients will help produce healthy, disorder-free nails.
Remember that your creativity in providing quality nail services must be grounded in a thorough knowledge and awareness of the structure and physiology of the nails.
SUMMARY AND REVIEW
• Well-manicured nails, whether natural or artificially applied, have always been recognized as an indication of good grooming
Nails originate in the epidermal layer of the skin and, like hair, their condition is dependent upon the individual’s overall health.
• A balanced diet filled with the daily required vitamins and nutrients will help produce healthy, disorder free nails.
• Remember that your creativity in providing quality nail services must be grounded in a thorough knowledge and awareness of the structure and physiology of the nails.

28. Chapter Review Questions
What is the technical term for the natural nail?
What is the major protein that makes up the natural nail?
Describe the appearance of a normal, healthy nail.
Name the basic parts of the nail unit.
CHAPTER REVIEW QUESTIONS
1. What is the technical term for the natural nail?
Answer: The technical term for the natural nail is onyx.
2. What is the major protein that makes up the natural nail?
Answer: The natural nail is comprised mainly of keratin, the same fiber protein found in skin and hair.
3. Describe the appearance of a normal, healthy nail.
Answer: A normal, healthy nail is firm but flexible and shiny. Its surface is smooth and unspotted, with no hollows or wavy ridges. A healthy nail also should be whitish and translucent in appearance, with the pinkish color of the nail bed below showing through.
4. Name the basic parts of the nail unit.
Answer: The basic parts of the nail unit are the nail bed, matrix, nail plate, cuticle, eponychium, perionychium, hyponychium, specialized ligaments, and nail folds.
(continues) 28

29. Chapter Review Questions (continued)
5. Explain the difference between the nail plate and the nail bed. 6. What part of the nail unit contains the nerves, lymph, and blood vessels? 7. What is the difference between the cuticle and the eponychium?
CHAPTER REVIEW QUESTIONS (continued)
5. Explain the difference between the nail plate and the nail bed.
Answer: The nail plate is the most visible and functional part of the nail unit. It is the hardened keratin plate that sits on and slowly slides across the nail bed while it grows. The nail plate is formed by matrix cells. The nail bed is the portion of living skin that supports the nail plate as it grows toward the free edge.
6. What part of the nail unit contains the nerves, lymph, and blood vessels?
Answer: The matrix contains nerves, lymph, and blood vessels to nourish the matrix cells.
7. What is the difference between the cuticle and the eponychium?
Answer: The cuticle is the dead, colorless tissue attached to the nail plate. The eponychium is the living skin at the base of the nail plate covering the matrix area.
(continues) 29

30. Chapter Review Questions (continued)
8. Why are cosmetologists not allowed to cut the skin around the base of the nail plate, even if the client requests this during the service? 9. What can affect the growth of the nail plate?
CHAPTER REVIEW QUESTIONS (continued)
8. Why are cosmetologists not allowed to cut the skin around the base of the nail plate, even if the client requests this during the service?
Answer: The eponychium is living skin at the base of the nail plate covering the matrix area. Clients cannot give cosmetologists permission to perform any medical procedures (i.e., cutting living skin). Cosmetologists are only permitted to gently push back the eponychium.
9. What can affect the growth of the nail plate?
Answer: The growth of the nail plate is affected by nutrition, exercise, seasons, pregnancy, and a person’s general health, including their age. 30