TY - CHAP M1 - Book, Section TI - Nail Findings A1 - Ubriani, Ravi A2 - Ali, Asra Y1 - 2015 N1 - T2 - McGraw-Hill Education Specialty Board Review Dermatology: A Pictorial Review, 3e AB - Nail plate (Fig. 3-1)Forms from keratinization of the nail matrix epithelium and is firmly attached to the nail bedDorsal nail plate is produced by the nail matrixVentral portion is produced by the nail bedNail thickness depends on the length of the nail matrix and nail bedPink color owing to underlying nail bed blood vesselsOnychocorneal band: most distal portion of firm attachment of the nail plate to the nail bedOnychodermal band: pink band that lies between the onychocorneal band and the nail plate white free edgeProximal nail foldDorsal portion: thinner than skin of the digit, devoid of pilosebaceous unitsVentral portion: in continuity with the matrix, adheres to the nail plate surface, and keratinizes with a granular layerHorny layer forms the cuticle and prevents the separation of the plate from the nail foldDermis contains numerous capillaries that run parallel to the surface of the skin; morphology can be altered in connective tissue diseasesNail matrixLies above the midportion of the distal phalanxKeratinization of the proximal nail matrix cells produces the dorsal nail plateKeratinization of the distal nail matrix cells produces the ventral nail plateLunula: where the distal matrix is not completely covered by the proximal nail fold but is visible through the normal nail plate as a white half-moon-shaped areaCells are able to synthesize both “soft,” or skin-type, and “hard,” or hair-type, keratins—the matrix expresses keratins Ha1, K1, K10Alteration in the color of lunula can be an indication of either a cutaneous or systemic disorder or a systemic drug side effectNail bedExtends from the distal margin of the lunula to the onychodermal bandCompletely visible through the nail plateEpithelium is adherent to the nail plate, 2 to 5 cell layersNail bed keratinization produces a thin horny layer that attaches to the ventral nail plateThe bed expresses keratins K6, K16, K17No granular layer is presentHyponychiumAnatomic area between the nail bed and the distal groove, where the nail plate detaches from the dorsal digitDermisNo subcutaneous tissue, no pilosebaceous unitsCondensed connective tissue that forms a tendon-like structure connecting the matrix to the periosteum of the phalangeal boneBlood and nerve supplyBlood supply provided by the lateral digital arteries, arches supply the matrix and nail bedSensory nerves: originate from the dorsal branches of the paired digital nerves, run parallel to the digital vesselsNail growthFingernails: 3 mm/mo, 0.1 mm/d, take 5 to 6 months to regrowToenails: 1 mm/mo, 0.03 mm/d, take 12 to 18 months to regrowAfter nail plate is avulsed, it takes 40 days before new fingernail will first emerge SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - dermatology.mhmedical.com/content.aspx?aid=1176104442 ER -