Accessory Structures of the Skin

apocrine sweat gland

type of sweat gland that is associated with hair follicles in the armpits and genital regions

arrector pili

smooth muscle that is activated in response to external stimuli that pull on hair follicles and make the hair "stand up" (i.e. "goose bumps" )

apocrine sweat gland

type of sweat gland that is associated with hair follicles in the armpits and genital regions

arrector pili

smooth muscle that is activated in response to external stimuli that pull on hair follicles and make the hair "stand up" (i.e. "goose bumps" )

cortex

in hair, the middle layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb

cuticle

in hair, the outermost layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb

eccrine sweat gland

type of sweat gland that is common throughout the skin surface; it produces a watery sweat for thermoregulation

eponychium

nail fold that meets the proximal end of the nail body, also commonly called the cuticle

hair

keratinous filament anchored by its root in the dermis of the skin

hair bulb

structure at the base of the hair root that surrounds the dermal papilla

hair follicle

cavity or sac from which hair originates; the hair follicle is composed of epithelial cells derived from the epidermis

hair matrix

layer of basal cells from which a strand of hair grows; area with a high rate of cell division (mitosis)

hair papilla

mass of connective tissue, blood capillaries, and nerve endings at the base of the hair follicle

hair root

part of hair that is below the epidermis and anchored to the follicle

hair shaft

part of hair that is above the epidermis but is not anchored to the follicle; it is the part of the hair that you can see, which like the outer layer of skin, is composed of dead, keratinized cells

hyponychium

thickened layer of stratum corneum that lies below the (distal) free edge of the nail

lunula

basal part of the nail body that consists of a crescent-shaped layer of thick epithelium; it appears white (take a look at your own nails!)

medulla

in hair, the innermost layer of keratinocytes originating from the hair matrix

nail bed

layer of epidermis upon which the nail body forms

nail body

main keratinous plate that forms the nail; it is composed of dead, keratinized cells; it is the part of the nail that you can see

nail cuticle

fold of epithelium that extends over the nail bed, also called the eponychium

nail fold

fold of epithelium at that extend over the sides of the nail body, holding it in place

nail root

part of the nail that is lodged deep in the epidermis from which the nail grows

sebaceous gland

type of oil gland found in the dermis all over the body and helps to lubricate and waterproof the skin and hair by secreting sebum; it is always associated with a hair follicle

sebum

oily substance that is composed of a mixture of lipids that lubricates the skin and hair

sudoriferous gland

sweat gland; types are eccrine and apocrine