7.1 Skin Structure of the Hands and Feet
Key Takeaways
- The NIC Nail Technology Theory Examination used for Arkansas manicurist licensure weights Anatomy and Physiology at 15 percent and asks for functions, parts, and structure of the skin.
- Stratum corneum is the dead outer keratin layer; stratum germinativum, also called stratum basale, is the living mitotic layer that produces new epidermal cells.
- Palms and soles have a thicker stratum corneum, a stratum lucidum, dense eccrine sweat glands, and no hair follicles or sebaceous glands.
- A callus is a broad pressure thickening of the corneum; a corn is a smaller, often painful cone over a bony prominence, and neither finding is a wart.
- Blood vessels and most sensory receptors live in the dermis and subcutaneous tissue; the epidermis is avascular.
Arkansas manicurist candidates take the National-Interstate Council of State Boards of Cosmetology (NIC) Nail Technology Theory Examination. On the NIC Candidate Information Bulletin effective September 1, 2025 (revised March 1, 2026), Scientific Concepts — Anatomy and Physiology is 15 percent of the 100 scored items. That domain asks you to identify the functions, parts, and structure of the skin, then to recognize disorders in a separate cluster of objectives. This section stays on healthy structure so you can describe what you are looking at on a palm, a nail fold, or a plantar pad before you decide whether a service is even appropriate.
The Arkansas Department of Health Cosmetology Section licenses this work under the manicurist title. Independent OpenExamPrep teaching for that license walks through the skin architecture the NIC outline names. It is study material for the written exam and for safer chair-side decisions. It is not a diagnosis service, and it does not replace the bulletin posted by your exam provider.
Skin is an organ, not a coat of polish. On the hands and feet it is the barrier between the client and water, files, primers, monomer vapor, and your hands. Items will mix structure stems (which layer divides?) with function stems (which role depends on sweat?) and regional stems (what is missing on the sole?). If you only memorize five Latin names, a palm-versus-dorsum question will still beat you.
The three-layer model
From the surface inward, name epidermis, dermis, and subcutaneous tissue (hypodermis). Keep their tissue types straight:
- The epidermis is stratified epithelium. It has no blood vessels. Nutrients diffuse upward from dermal capillaries.
- The dermis is connective tissue. It holds vessels, nerves, glands, and — where hair exists — follicles.
- The subcutaneous layer is mostly adipose and loose connective tissue. It pads bony points, stores energy, and helps insulate.
A common trap is to park blood, lymph, or "the sweat gland itself" inside the epidermis. Gland openings reach the palmar surface; the gland coils and the supporting vessels sit in dermis or subcutaneous tissue.
Epidermis: corneum and germinativum first
Two names dominate nail-exam items.
Stratum corneum (horny layer) is the outermost sheet of flattened, keratin-filled cells that are no longer living. It is what you see as dry scale, what a dehydrator dries, and what stacks into a callus. Palms and soles grow a much thicker corneum than the back of the hand, which is why a foot file and a nail buffer are not interchangeable tools.
Stratum germinativum, also called stratum basale, is the deepest epidermal layer: a single row of living cells that divide by mitosis. Daughter keratinocytes move toward the surface, fill with keratin, flatten, and become corneum. Melanocytes in this layer produce melanin. Salon work should never chase this living layer with a blade, bit, or acid. Bleeding, or a shiny moist pink surface after aggressive filing, means you have gone too far.
Learn the remaining strata so distractors cannot hide:
| Layer (outside to inside) | Exam-useful fact |
|---|---|
| Stratum corneum | Dead keratin; thickest on palms and soles; the surface of a callus |
| Stratum lucidum | Clear extra layer on palms and soles; extra toughness under the corneum |
| Stratum granulosum | Granules of keratin-forming material; cells flattening |
| Stratum spinosum | "Spiny" keratinocytes; immune Langerhans cells live here |
| Stratum germinativum / basale | Mitosis; melanocytes; the living factory of the epidermis |
| Papillary dermis | Friction ridges, capillary loops, light-touch receptors |
| Reticular dermis | Collagen, eccrine glands, follicles on hairy skin, deeper nerves |
| Subcutaneous tissue | Adipose padding under heels, metatarsal heads, and palms |
Stratum lucidum is the palm-and-sole extra. It is a thin, clear band of extra keratin between corneum and granulosum, prominent on palmar and plantar skin and typically not a distinct layer on thin dorsal skin. That extra sheet is one reason the ball of the foot feels glassy after a soak and files as a dense pad rather than as thin facial-type skin.
The epidermis replaces itself continuously. You do not need a histology timer on the exam, but you do need the logic: the surface you buff is dead; the factory is basal; pigment and mitosis live deep; vessels do not.
Dermis: papillae, glands, and feeling
The dermis begins at the basement membrane under the basal layer.
Papillary dermis is the thin upper zone. Dermal papillae interlock with the epidermis. On palmar and plantar surfaces those ridges become friction ridges — fingerprints and footprints — that improve grip and make each client's pattern unique. Capillary loops in the papillae feed the avascular epidermis. Light-touch receptors here explain why a client flinches at a cuticle pusher long before you reach muscle.
Reticular dermis is thicker, with denser collagen and elastin. Here you find eccrine (sudoriferous) sweat glands, sebaceous glands on hairy skin, hair follicles, deeper pressure receptors, and the vascular net that flushes a hand pink in a warm room.
If a stem asks which layer contains the nerves and blood vessels of the skin, choose dermis (with some continuation into subcutaneous tissue), not epidermis. If it asks why a nervous client's palms are wet, think dermal eccrine glands emptying onto palmar skin — not sebaceous oil. Palms and soles do not have sebaceous glands.
Subcutaneous tissue
The subcutaneous layer is the fat-rich pad over the calcaneus, under the metatarsal heads, and in the palm. It cushions, insulates, and lets skin glide when you massage. Thin padding over a bunion, hammertoe, or prominent metatarsal head is why those sites corn: bone and shoe meet with less adipose in between. You do not "break up" this layer, inject it, or treat a bruise or abscess in it. Swollen, hot, or dusky subcutaneous tissue is a medical finding, not a massage target.
Functions you must be able to name
NIC language asks for functions as well as parts. Keep these five ready; a sixth, absorption, appears when chemistry chapters discuss products entering broken skin.
- Protection. Intact corneum, melanin, and an acid mantle limit microbes, actinic damage, and many chemicals. Over-filing, cracked heels, and hangnails remove that armor.
- Sensation. Receptors for touch, pain, pressure, and temperature sit in dermis and subcutaneous tissue. They are why hot paraffin, a spinning bit, or a tight clipper must be checked against what the client actually feels.
- Temperature regulation. Dermal vessels dilate or constrict; sweat evaporates. Palms and soles are sweat-forward surfaces.
- Excretion. Eccrine sweat carries water, salts, and small wastes onto the skin. Items use "excretion" for that gland activity; it is not a claim that the skin replaces the kidney.
- Vitamin D production. Ultraviolet light on the skin starts vitamin D synthesis. Hands may see sun; feet in closed shoes usually do not. You will not dose vitamin D in a salon; you may see it listed among skin functions.
Sebum secretion is a function of hairy skin. Do not assign oil glands to palms or soles.
Hands and feet: the regional rules
Thicker stratum corneum. Repeated gripping and weight-bearing stimulate keratin. A bakery worker in Little Rock and a guitarist will not present the same pads. Plantar skin under the metatarsal heads is a specialized, thick epidermis.
No hair follicles on palms or soles, and therefore no sebaceous glands there. Dorsal hands and feet can have hair. A question that plants a follicle in the center of the palm is a trap.
Eccrine sweat glands are dense on palmar and plantar skin. Moisture affects polish and tip adhesion, massage slip, and shoe odor. The next section treats hyperhidrosis, bromhidrosis, and anhidrosis as disorders of this system.
Callus versus corn. Both are hyperkeratosis of the corneum. They are not viruses and not, by themselves, abscesses.
- A callus (keratoma) is a broader, more even thickening from repeated friction or pressure — the ball of the foot, the radial thumb that opens jars. It is often painless until it fissures.
- A corn (clavus) is a smaller, deeper, conical thickening, often over a joint or hammertoe, often painful because the core presses nerve endings. Hard corns sit on dry dorsum or toe apices; soft corns sit in moist web spaces.
Do not reduce bleeding, draining, or spreading lesions. Do not treat a wart as a callus. Gentle reduction of intact, clearly non-infectious callus can be part of a pedicure within manicurist scope; coring a painful unidentified cone is not.
Salon picture
A client who stands on concrete has even, yellowish thickening under the metatarsal heads and a pinpoint, sharp pain on the dorsum of the fifth toe where a dress shoe rubs. Those are two findings: occupational plantar callus, and a suspected corn over a bony point. File only dry, intact, non-viral-looking keratin; stop at pink or blood; refer a lesion you cannot identify.
Traps to retire before test day
Do not place blood vessels in the epidermis. Do not swap stratum corneum (dead surface) with stratum germinativum or basale (living mitosis). Do not give palms hair or oil glands. Do not call a corn a wart. Confirm current domain wording on the NIC bulletin your Arkansas provider posts; this chapter teaches the skin facts those items use.
A client asks why the skin on the palms feels tougher than the skin on the back of the hand. Which layer is the outermost keratin sheet most responsible for that toughness?
Which statement about palmar and plantar skin is accurate for nail services?
Compared with a corn, a callus is typically which finding?