RT Book, Section
A1 Tosti, Antonella
A1 Piraccini, Bianca Maria
A2 Goldsmith, Lowell A.
A2 Katz, Stephen I.
A2 Gilchrest, Barbara A.
A2 Paller, Amy S.
A2 Leffell, David J.
A2 Wolff, Klaus
SR Print(0)
ID 56050454
T1 Chapter 89. Biology of Nails and Nail Disorders
T2 Fitzpatrick's Dermatology in General Medicine, 8e
YR 2012
FD 2012
PB The McGraw-Hill Companies
PP New York, NY
SN 978-0-07-166904-7
LK accessmedicine.mhmedical.com/content.aspx?aid=56050454
RD 2024/09/20
AB The  nail  apparatus  consists  of  a  horny  “dead”  product,  the  nail  plate,  and  four  specialized  epithelia:  (1)  the  proximal  nail  fold,  (2)  the  nail  matrix,  (3)  the  nail  bed,  and  (4)  the  hyponychium  (Fig.  89-1A).  The  nail  apparatus  develops  during  the  9th  embryonic  week  from  the  epidermis  of  the  dorsal  tip  of  the  digit  as  a  rectangular  area,  the  nail  fold  that  is  delineated  by  a  continuous  groove.1  The  proximal  border  of  the  nail  fold  extends  downward  and  proximally  into  the  dermis  to  form  the  nail  matrix  primordium.  By  the  15th  week  the  nail  matrix  is  completely  developed  and  starts  to  produce  the  nail  plate,  which  will  continue  to  grow  until  death.  The  nail  apparatus  lies  immediately  above  the  periosteum  of  the  distal  phalanx.  The  intimate  anatomic  relationship  between  the  nail  and  the  bone  is  responsible  for  the  common  occurrence  of  bone  alterations  in  nail  disorders  and  vice  versa.  The  shape  of  the  distal  phalangeal  bone  also  determines  the  shape  and  the  transverse  curvature  of  the  nail.