Nail Anatomy

Aka: Nail Anatomy, Fingernail, Toenail, Nail Growth, Hyponychium, Eponychium, Nail Cuticle, Toe Cuticle, Finger Cuticle

II. Anatomy

  1. Images
    1. DermNailAnatomy.jpg
    2. dermNailBaseGrayBB943.gifLewis (1918) Gray's Anatomy 20th ed (in public domain at Yahoo or BartleBy)
  2. Cuticle
    1. Intersection between nail plate and overlying skin at proximal nail
  3. Germinal matrix
    1. Root of the nail
    2. Forms nail plate from base of nail bed
    3. Distal matrix produces deeper nail plate
      1. Disruption may cause deep nail ridges
    4. Proximal matrix produces superficial nail plate
      1. Disruption may cause superficial Nail Pitting
  4. Eponychium
    1. Skin just proximal to cuticle
    2. Dorsal fold at proximal surface of nail
    3. Binds nail to underlying skin at proximal margin
  5. Paronychial edge or Perionychium
    1. Lateral borders of nail
    2. Site of hangnails and Paronychia
  6. Hyponychium
    1. Area beneath free edge of nail
    2. Junction where nail bed meets tip of digit skin
  7. Nail Plate
    1. Hard and translucent
    2. Composed of dead keratin
    3. Surrounded by perionychium
  8. Nail Bed (Sterile Matrix)
    1. Adheres to underside nail with squamous epithelium
    2. Makes nail plate thicker and stronger
    3. Contains blood vessels and nerves

III. Physiology: General

  1. Nail is keratinized squamous cells
  2. Forms protective plate
    1. Prevents infection of underlying skin
  3. Enhances fingertip sensation
    1. Nail acts as counterforce to fingertip
    2. Two Point Discrimination decreased when nail absent
  4. Attachment of nail to skin
    1. Proximal: Eponychium
    2. Distal: Anterior ligament, distal nail fold
    3. Lateral: Lateral nail folds

IV. Physiology: Nail Growth

  1. Normal Nail Growth
    1. Fingernails
      1. Grow 3 mm per month
      2. Require 6 months for complete re-growth
    2. Toenails
      1. Require 12-18 months to replace (2-3 times as long to re-grow as Fingernails)
  2. Arrested Nail Growth
    1. Caused by any systemic illness
    2. Results in deep transverse grooves (Beau's Lines)

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Related Studies

Ontology: Eponychium (C0221994)

Concepts Body Part, Organ, or Organ Component (T023)
SnomedCT 24631007
English Eponychium, Eponychium (body structure)
Spanish eponiquio (estructura corporal), eponiquio, eponychium
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Structure of hyponychium (C0221998)

Concepts Body Part, Organ, or Organ Component (T023)
SnomedCT 89699003
English Hyponychium, Structure of hyponychium (body structure), Structure of hyponychium
Spanish estructura del hiponiquio (estructura corporal), estructura del hiponiquio, hiponiquio, hyponychium
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Structure of nail of finger (C0222001)

Definition (NCI_CDISC) The nail at the end of a finger. (NCI)
Definition (NCI) The nail at the end of a finger.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D009262
SnomedCT 400133005, 91456000
HL7 FINGN, NAILF
Portuguese Unhas das Mãos
Spanish Uñas de las Manos, estructura de uña de dedo de la mano (estructura corporal), estructura de la uña de un dedo de la mano (estructura corporal), estructura de la uña de un dedo de la mano, estructura de uña de dedo de la mano, uña de dedo de la mano
French Ongles des doigts
German Fingernägel
English Finger nail, Nail plate of finger, Nails of fingers, Finger nails, Set of nails of fingers, fingernail, fingernails, FINGERNAIL, Fingernail, Nail of finger, Structure of nail of finger (body structure), Structure of nail of finger, Nail of finger, NOS, Finger Nail, Fingernails, Nail, Finger
Italian Unghie delle dita delle mani
Norwegian Fingernegler
Czech nehty na rukou
Dutch Vingernagels
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Structure of nail of toe (C0222007)

Definition (NCI_CDISC) A thin, horny translucent plate covering the end of each toe. (NCI)
Definition (NCI) A thin, horny translucent plate covering the end of each toe.
Concepts Body Part, Organ, or Organ Component (T023)
MSH D009262
SnomedCT 76578001
HL7 TOEN, NAILT
LNC LP30554-7, MTHU015074
French Ongles des doigts de pied, Ongles des orteils
Portuguese Unhas dos Pés
Spanish Uñas de los Pies, estructura de la uña del dedo del pie, estructura de uña de dedo del pie (estructura corporal), estructura de la uña del dedo del pie (estructura corporal), estructura de uña de dedo del pie, uña del dedo del pie, uña de dedo del pie, uña del pie
German Zehennägel
English Set of nails of toes, Toe nail, Toe nails, Nail plate of toe, Nails of toes, toenail, toenails, TOENAIL, Nail of toe, Toenail, Structure of nail of toe (body structure), Structure of nail of toe, Nail of toe, NOS, Toe Nail, Toenails, Nail, Toe
Italian Unghie delle dita dei piedi
Norwegian Tånegler
Czech nehty na nohou
Dutch Teennagels
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Eponychium of finger (C0930791)

Concepts Body Part, Organ, or Organ Component (T023)
English Finger eponychium, Eponychium of finger, Cuticle of finger, finger cuticle, eponychium of finger, cuticles finger
Derived from the NIH UMLS (Unified Medical Language System)

Ontology: Eponychium of toe (C0930793)

Concepts Body Part, Organ, or Organ Component (T023)
English Cuticle of toe, Eponychium of toe, Toe eponychium
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Anatomy

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