Hair and Scalp Anatomy, Disorders, and Treatments
This domain tests the structure and growth cycle of hair, the layers of the shaft, and the scalp and hair conditions a barber will see. The exam expects you to recognize what is cosmetic, what is contagious, and when the correct answer is to refer.
Structure and growth
- Each hair grows from a follicle; the bulb sits at the base, fed by the papilla's blood supply, with a sebaceous gland and arrector pili muscle attached.
- The shaft has three layers: the cuticle (outer protective scales), the cortex (bulk, where disulfide bonds and pigment live), and the medulla (central core, sometimes absent).
- Hair types are lanugo (fetal, shed before birth), vellus (fine, unpigmented), and terminal (thick and pigmented).
- The growth cycle: anagen (active, two to seven years, about 90 percent of hair), catagen (transition, two to three weeks), telogen (rest, three to four months), then shedding. Losing 50 to 100 hairs a day is normal.
Scalp and hair conditions
- Pityriasis capitis (dandruff): flaking, not contagious; medicated shampoo is appropriate.
- Seborrheic dermatitis: red, greasy scales; refer if severe or inflamed.
- Tinea capitis (ringworm): fungal, contagious; scaly circular patch, broken hairs, sometimes pustules - do not service, refer.
- Pediculosis: lice and nits; do not service, refer.
- Folliculitis, furuncle, carbuncle: bacterial; avoid the area and refer.
- Alopecia areata: smooth, well-defined patches, autoimmune and not contagious; refer.
- Androgenetic alopecia: pattern thinning; traction alopecia follows tight styling; trichorrhexis nodosa is splitting from overprocessing.
Hair analysis
- Porosity: hair that floats then sinks slowly is normal; hair that sinks fast is highly porous.
- Elasticity: wet hair should stretch and return; poor elasticity means breakage risk.
- Density (thin, medium, thick) and texture (fine, medium, coarse) guide tool and product choices.
Worked example
A client has a circular scaly patch with broken hairs and itching. Do not shampoo or cut over it, do not treat it with dandruff shampoo, refer the client to a physician, and disinfect all tools afterward. Reasoning: barbering is cosmetic; diagnosing and medicating a suspected fungal infection is outside scope, and servicing could spread it.
Traps that cost marks
- Treating tinea capitis as ordinary dandruff.
- Assuming alopecia areata is contagious.
- Confusing lanugo with vellus hair.
- Calling every hair loss normal shedding.