Skin Anatomy

Divided into epidermis and dermis
- Epidermis is ectodermal in origin - within it are sweat glands, sebaceous glands, hair and nails.
- The dermis is mesodermal in origin - within it is fat and collagen, blood vessels and lymphatics.

Layers of the epidermis - “Come, Let’s Get Sun Burned”

Stratum corneum - consists of 15-20 layers of flattened dead cells with no nuclei.
Stratum lucidum - consists of dead keratinocytes filled with eleidin (intermediate form of keratin), and a clear.
Stratum granulosum - thin layer of keratinocytes
Stratum spinosum
Stratum basale - is the basal layer. Have large nuclei which occupy the majority of the cell.

Layers of the dermis

Papillary dermis - intertwines with rete ridges of the epidermis and is composed of loose areolar connective tissue.
Reticular dermis - lowermost part of the dermis. Composed of dense collagen rich connective tissue.

Sweat glands

Distributed everywhere except on the lips, nipples, glands penis and labia minora
Apocrine glands are large, modified sweat glands confined to the axillae, areolae, periumbilical, genital and perianal regions; their ducts open into hair follicles or directly on to the skin surface. Their odourless secretion acquires a smell through bacterial action

Are a type of hard keratin
Each hair is formed from the hair matrix, a region of epidermal cells at the base of hair follicle which extends into the dermis.
A erector pili muscle is attached to the hair follicle.

Nail consists of a nail plate, the nail matrix, and the nail bed below it.
Nail matrix is the active tissue that generate cells.
The cells harden as they move outward from the nail root to the nail plate.
As new nail plate cells are made, they push older plate cells forward
The lunula (“small moon”) is the visible part of the matrix.
The nail bed is beneath the nail plate
The nail root is located just under the skin at the proximal nail fold.
The nail plate is from the nail root to the free edge, and is made of dead, compacted cells which are keratin dense.