Skin appendages (or adnexa of skin) are anatomical skin-associated structures that serve a particular function including sensation, contractility, lubrication and heat loss in animals. In humans, some of the more common skin appendages are

hair Hair is a protein filament that grows from follicles found in the dermis. Hair is one of the defining characteristics of mammals. The human body, apart from areas of glabrous skin, is covered in follicles which produce thick terminal and f ...

s (sensation, heat loss, filter for breathing, protection),

arrector pilli The arrector pili muscles, also known as hair erector muscles, are small muscles attached to hair follicles in mammals. Contraction of these muscles causes the hairs to stand on end, known colloquially as goose bumps (piloerection). Structure ...

(smooth muscles that pull hairs straight),

sebaceous gland A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number ...

s (secrete sebum onto hair follicle, which oils the hair),

sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...

s (can secrete sweat with strong odour (

apocrine Apocrine () glands are a type of exocrine gland, which are themselves a type of gland, i.e. a group of cells specialized for the release of secretions. Exocrine glands secrete by one of three means: holocrine, merocrine and apocrine. In apocrine ...

) or with a faint odour (

merocrine Merocrine (or eccrine) is a term used to classify exocrine glands and their secretions in the study of histology. A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelia ...

or eccrine)), and nails (protection). Skin appendages are derived from the

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...

, and are usually adjacent to it. Types of appendages include hair, glands, and nails.

Glands

Sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial sur ...

s are distributed all over the body except nipples and outer genitals. Although the nipples do have the mammary glands, these are known as ''modified sweat glands''. *

Sebaceous gland A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number ...

s are typically found in the opening shaftn of hair. They are not on the palms of the hands or the soles of the feet. These glands secrete an antibacterial moisture known as ''sebum fluid''. The sebum also softens the hands. The secretion activity is related to hormonal release. If acne is occurring, it is because these gland ducts are blocked. * Eccrine (merocrine) glands are most common. The secretions are very watery that contain some electrolytes *

Apocrine gland Apocrine () glands are a type of exocrine gland, which are themselves a type of gland, i.e. a group of cells specialized for the release of secretions. Exocrine glands secrete by one of three means: holocrine, merocrine and apocrine. In apocrine ...

s produce a fatty secretion, thus giving away an odorous smell. These are located in the inguinal and axillary regions of the body, and include the mammary glands as well as the creaminess variants.

References

Skin anatomy {{dermatology-stub