Hair follicle

Function

The hair follicle is a mini-organ: a shaft factory with a dermal papilla commanding the matrix, a sebaceous gland emptying into the neck, an arrector pili muscle to goose-bump, and a bulge of stem cells that regrow it cycle after cycle and repair wounded epidermis.

Its depth anchors it through the dermis into the hypodermis — the reason deep burns that spare follicles heal, and the reason hair-bearing donor sites supply grafts.

Blood supply

Dermal papilla and perifollicular plexus.

Nerve supply

Sympathetic pilomotor fibres; follicular nerve endings detect the slightest hair bend.

Clinical relevance

Acne

Androgen-driven sebum plus follicular occlusion breeds Cutibacterium acnes — the inflammation of the adolescent follicle.

Folliculitis

Surface infection of follicles — the itchy pustules of occluded skin, hot tubs and shaving.

Related conditions

• Acne vulgaris