Anatomy, Physiology, and Skin Disorders
Anatomy, Physiology, and Skin Disorders
This domain tests head, face, and neck anatomy, skin and hair structure, growth cycles, and recognition of lesions that require referral. You must know what is normal, what is treatable in the shop, and what is out of scope.
Core rules
- Skin layers: epidermis, dermis, subcutaneous tissue. The follicle, sebaceous gland, arrector pili muscle, and nail are appendages.
- Hair growth cycle: anagen (growth), catagen (transition), telogen (rest). Growth rate and shedding vary by site and person.
- Key muscles include frontalis, temporalis, masseter, and the muscles of facial expression. The trigeminal nerve supplies sensation to the face; know its main branches for safe service.
- Lesion terms: macule (flat color change), papule (raised), pustule (pus-filled), cyst (sac-like), wheal (hives), and fissure (crack). Primary lesions are initial; secondary are changed by scratching or healing.
- Contagious or suspicious findings-tinea barbae, impetigo, lice, herpes with active sores, undiagnosed growths-require no service and referral.
Worked example
A client has pustules and ingrown hairs along the beard area after shaving. This looks like pseudofolliculitis barbae, not necessarily infection. You avoid close shaving over the area, recommend a physician if it is painful or spreading, and use gentle exfoliation advice. You do not lance or treat the pustules.
Traps
Diagnosing skin disease; treating lesions; massaging over infection; shaving over active herpes; confusing a normal mole with a dangerous growth; ignoring lymph nodes or spreading redness.