A&P Honors: Ch. 5.6 — Nails

What does a nail form?

Protective covering on the dorsal surface of the distal part of a finger or toe.

What does each nail have?

A proximal root, a nail plate or body, and a free edge.

What is a proximal root?

The part of the nail embedded in the skin.

What is the nail plate or body?

The part that is visibly attached.

What is the nail bed?

Where the nail rests.

What does the nail bed contain? Why?

Only deeper layers of the epidermis, because the nail itself corresponds to the superficial keratinized layers.

What is the nail matrix?

The thickened proximal portion of the nail bed that is responsible for nail growth.

Why do nails appear pink?

Because of the rich bed of capillaries in the underlying dermis.

What is the lunule?

The region that lies over the thick nail matrix that appears as a white crescent.

What are nail folds?

The proximal and lateral borders of the nail that are overlapped by skin folds.

What do the proximal nail folds project onto the nail body as?

The cuticle or eponychium.

What is the hyponychium?

The thickened region beneath the free edge of the nail where dirt and debris tend to accumulate.

What secures the free edge of the nail plate at the tip of the finger or toe?

The hyponychium.

What do yellow tinged nailed indicate?

A respiratory or thyroid gland disorder.

What does an outward concavity of the nail or koilonychia (spoon nail) signal?

An iron deficiency.

What are horizontal lines along the nail called?

Beau’s lines

What can Beau’s lines be a sign of?

Severe illness that affects the whole body such as uncontrolled diabetes, a heart attack, or cancer chemotherapy.