Nail (anatomy)

: This article discusses the anatomical nail. For other uses of the term, see nail.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

In anatomy, a nail is a horn-like piece at the end of a human or animal finger or toe. See also claw.

Related Topics:
Anatomy - Horn - Finger - Toe - Claw

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Fingernails and toenails are composed of:

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

• the nail matrix or the root of the nail - this is the growing part of the nail still under the skin at the nail's proximal end.
• eponychium or cuticle which is the fold of skin at the proximal end of the nail.
• paronychium which is the fold of skin on the sides of the nail.
• hyponychium which is the attachment between the skin of the finger or toe and the distal end of the nail.
• nail plate which is what we think of when we say nail, the hard and translucent portion, composed of keratin.
• nail bed which is the adherent connective tissue that underlies the nail.
• lunula which is the crescent shaped whitish area of the nail bed.

Fingernails require 3 to 6 months to regrow completely. Toenails require 12 to 18 months. Any major illness will cause a groove to form in the nails, marking in time the past medical history of its owner. These are called Beau's lines.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nails grow at an average rate of 0.1 mm/day (1 cm every 100 days) {{ref|growthrate}}. The average is not constant, though, and actual growth rate is dependent upon age, season, exercise level, and hereditary factors.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Nails can become thickened (onychogryphosis), loosened (onycholysis), infected with fungus (onychomycosis) or degenerative (onychodystrophy); for further information see nail diseases.

Related Topics:
Onychogryphosis - Onycholysis - Onychomycosis - Onychodystrophy - Nail disease

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

 
Nail (anatomy): Care ►