Skin Appendages -- epidermal derivatives such as hair follicles, glands, etc. whose distribution, arrangement, and structural details vary greatly in skin on different parts of the body.

Examine several hair follicles cut transversely on slides 17 and 36.

In the hair shaft itself, identify if possible the

• Medulla,
• Cortex, and
• Cuticle.
  • Not all layers may be evident, depending on the plane of section.
• Identify the internal and external root sheathes of the follicle.

Examine hair follicles cut longitudinally, and again identifying as many layers as possible. Identify

• Sebaceous glands, pictured to the right, and
• Arrector pili muscle associated with hair follicles.

What is the function of the “pilosebaceous unit” in the skin?

Examine the structure of nails and their association with other parts of a digit as shown on the demo slide (Fig. 18-14).

How does the structure of a nail and nail bed compare with that of a hair follicle?

Next is the cartilage and bone.