Nail biology and nail science

Abstract

Synopsis The nail plate is the permanent product of the nail matrix. Its normal appearance and growth depend on the integrity of several components: the surrounding tissues or perionychium and the bony phalanx that are contributing to the nail apparatus or nail unit. The nail is inserted proximally in an invagination practically parallel to the upper surface of the skin and laterally in the lateral nail grooves. This pocket‐like invagination has a roof, the proximal nail fold and a floor, the matrix from which the nail is derived. The germinal matrix forms the bulk of the nail plate. The proximal element forms the superficial third of the nail whereas the distal element provides its inferior two‐thirds. The ventral surface of the proximal nail fold adheres closely to the nail for a short distance and forms a gradually desquamating tissue, the cuticle, made of the stratum corneum of both the dorsal and the ventral side of the proximal nail fold. The cuticle seals and therefore protects the ungual cul‐de‐sac. The nail plate is bordered by the proximal nail fold which is continuous with the similarly structured lateral nail fold on each side. The nail bed extends from the lunula to the hyponychium. It presents with parallel longitudinal rete ridges. This area, by contrast to the matrix has a firm attachment to the nail plate and nail avulsion produces a denudation of the nail bed. Colourless, but translucent, the highly vascular connective tissue containing glomus organs transmits a pink colour through the nail. Among its multiple functions, the nail provides counterpressure to the pulp that is essential to the tactile sensation involving the fingers and to the prevention of the hypertrophy of the distal wall tissue, produced after nail loss of the great toe nail.

Nail Surgery for Beginners

“…T›rnaklar, epidermisin dermis içine do¤ru cep gibi k›vr›mlanmas›yla gestasyonun 8. haftas›nda ilk olarak seçilirler ve 17. haftadan itibaren t›rnak pla¤›, t›rnak yata¤› üzerine oturur. ‹çeri do¤ru katlanm›fl bu epidermal invajinasyonun tavan›n› proksimal t›rnak katlant›s›, taban›n› ise t›rnak matriksi oluflturur 1 . T›rnak matriksi t›rnak yata¤› ile devam eder.…”

“…Distal matriks ise, t›rnak pla¤›n›n alt›nda beyaz yar›may www.turkderm.org.tr DOI: 10.4274/turkderm.44.123 fleklinde (lunula) görülür. T›rnak matriksi oblik bir aks› takip ederek keratinize olur; dolay›s›yla proksimal matriks, t›rnak pla¤›n›n dorsal yüzünü, distal matriks ise t›rnak pla¤›n›n ventral yüzünü oluflturur [1][2][3][4] . T›rnak matriks hücrelerinin keratinize olmas›yla t›rnak pla¤› oluflur.…”

“…T›rnak matriks hücrelerinin keratinize olmas›yla t›rnak pla¤› oluflur. T›rnak matriks epiteli, granüler katman oluflturmadan keratinize olmas›yla karakterizedir; dolay›s›yla t›rnak matriks histolojisinde stratum granülozum görülmez 1,3,4 . T›rnak pla¤›n› tamamen keratinize ölü hücreler, 'onikosit/korneosit' ler oluflturur.…”

“…T›rnak pla¤›n› tamamen keratinize ölü hücreler, 'onikosit/korneosit' ler oluflturur. T›rnak pla¤›, epidermisin stratum korneumuna benzetilebilir, sert keratindir 1,4 . Plak, t›rnak yata¤›na çok s›k› yap›fl›kt›r ve deskuame olmaz.…”

“…T›rnak ünitesi proksimal ve lateral kutanöz k›vr›mlarla çevrili, distalde hiponiflyum derisiyle devaml›d›r. Hiponiflyum, parmaklar›n, palmar bölge derisinin devam›d›r [1][2][3][4] . T›rnak matriksi t›rna¤› oluflturan üretim merkezidir.…”