Skin Histology Epidermal Derivatives J.F. Thompson, Ph.D. Chapter 5 Skin Histology Epidermal Derivatives J.F. Thompson, Ph.D.

Hair Distribution Varies Over the Body Surface

Hair Follicles

Hair Anatomy Shaft Root Follicle - surrounds root medulla - inner layer cortex - middle layer, pigments, air spaces cuticle - outermost layer, hard keratin Root similar to shaft, but within dermis Follicle - surrounds root Sheath - supports shaft & root Bulb - enlarged layered structure at base where hair is generated papilla - areolar connective tissue, blood vessels supply nutrients matrix - germination layer of papilla (stratum basale) builds hair shaft Sebaceous glands – release oil Arrector Pili – smooth muscle

Hairs & Lice egg crab louse head louse

Arrector Pili (smooth muscle)

Sweat Glands

Sebaceous Glands

Nails tightly packed, hard, keratinized cells nail matrix - under root of nail site of nail growth transforms normal skin cells into nail cells which push forward 1mm/week in fingers; slower in toes the longer the finger the greater the growth rate

Nails Tightly packed cells with hard keratin Nail matrix - under root of nail site of nail growth transforms normal skin cells into nail cells which push forward 1mm/week in fingers; slower in toes the longer the finger the greater the growth rate

Hypodermis

Skin Histology Epidermal Derivatives End Ch 5 Skin Histology Epidermal Derivatives