Anatomy, Physiology, and Histology of the Skin
Build the skin from the inside out
The subcutaneous layer is fat and insulation. The dermis has two parts: the papillary layer, which holds capillaries and feeds the skin, and the reticular layer, packed with collagen and elastin for strength and elasticity. The epidermis is avascular - it has no blood vessels and is nourished by diffusion from the dermis. That single fact answers a lot of exam items.
Epidermal layers, bottom to top
Stratum basale (mitosis happens here, and melanocytes live here), stratum spinosum, stratum granulosum, stratum lucidum (palms and soles only), stratum corneum (keratin, shedding). Cells to name: keratinocytes (the majority), melanocytes (pigment), Langerhans cells (immune defense), Merkel cells (touch).
Appendages and glands
Sebaceous glands attach to hair follicles and secrete sebum. Sudoriferous glands are sweat glands: eccrine (whole body, temperature control) and apocrine (axillae and groin, associated with body odor). The hair follicle holds the bulb, papilla, and arrector pili muscle.
Nerves, muscles, bones
Cranial nerve V, the trigeminal, carries sensation from the face; cranial nerve VII, the facial nerve, is motor and controls expression. Masseter and temporalis are muscles of mastication, not expression. Bones of the face include the frontal, zygomatic, maxilla, mandible, nasal, and temporal.
Traps
Expect distractors that put blood vessels in the epidermis, melanocytes in the corneum, or stratum lucidum everywhere on the body. Sebaceous versus sudoriferous is a favorite swap.
Rule of thumb
Epidermis = protection, no blood supply; dermis = structure and nourishment; subcutis = fat and cushion. Match each layer to its job and the distractors fall away.