Nail technicians work on skin as much as on nails, and the exam's skin-structure questions are straightforward once you know the layers from the outside in.
Three layers
- The epidermis is the outermost layer. It is about 1.5 mm thick on the palms and soles, and only 0.05 mm on the eyelids.
- The dermis lies beneath it and contains nerve endings, sweat glands, oil glands and hair follicles. It is held together by collagen, made by fibroblasts, while elastin lets the skin spring back and stay flexible.
- The subcutis (hypodermis) is the fatty layer of subcutaneous tissue underneath.
Inside the epidermis
- The stratum corneum, or horny layer, is the outermost part: 10 to 30 thin layers of dead cells that continually shed.
- The basal layer (stratum germinativum) is the deepest. Its cells continually divide and push older cells up.
- Melanocytes in the basal layer produce melanin, which gives skin its color and helps protect the deeper layers from the sun.
Keratin: the link to nails
Keratinocytes produce keratin, a tough protective protein that makes up most of the skin, hair and nails. Nails are layers of hardened keratin, which is why a nail hardener works by bonding with it.
Glands
Sebaceous (oil) glands are attached to hair follicles and found everywhere except the palms of the hands and the soles of the feet.
Why it matters on the job
Melanoma can occur in the nail bed, so a new or changing dark streak under a nail is a reason to refer the client to a doctor. Our guide to nail and skin disorders covers when to refer.