File:A practical treatise on diseases of the skin, for the use of students and practitioners (1897) (14784179015).jpg

Identifier: practicaltreati00hyd (find matches)
Title: A practical treatise on diseases of the skin, for the use of students and practitioners
Year: 1897 (1890s)
Authors: Hyde, James Nevins, 1840-1910 Montgomery, Frank Hugh, 1862- joint author
Subjects: Skin
Publisher: Philadelphia, New York, Lea brothers & co.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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tion it is easy to understand that the nail is consti-tuted of horny filaments, or coherent strata of cornified cells, passingfrom the matrix or floor of the nail-fold. The upper surface of thenail grows, therefore, from the bottom of the nail-fold; the undersurface from the lunula; and the intermediate layers proportionatelyfrom the parts between, that interlock with corresponding grooves onthe upper face of the bed. ANATOMY AND PHYSIOLOGY OF THE SKIN. 49 The Nail-fold, crescentic iu shape, clasps the nail posteriorly andlaterally. It is formed of connective tissue, whose bundles are inter-penetrated by numerous coil-glands and fat-columns. The epidermisbeneath the nail exhibits prickle, granular, and horny layers. As thenail is gradually liberated from its bed both at the sides and point, thecornification of the horny layer becomes more complete, so that finally,as the nail-plate is pushed forward, it no longer rides over the cells ofthe rete, but over a completely cornified tissue.
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Implantation of the nail at its border: P, papillae decreasing in size toward the middle line;R, rete mucosum, which broadens toward the border of the nail, and forms irregular prolonga-tions; R, E, epidermal layer; N, plate of the nail. Magnified 500 diameters. (After Heitzmann.) If the pulp of any nail-bearing phalanx be pressed with moderateforce against any firm object, the naked eye can detect upon the surfaceof the nail, just behind its free border, a yellowish-white band, convexanteriorly and somewhat increasing in width laterally. This line isalso visible when no pressure is exerted upon the digit, its width vary-ing under the conditions described. This border represents the spacein which the three layers of the epidermis from the skin of the pointof the finger, viz., the horny, the granular, and the prickle-layer, suc-cessively come in contact with the under surface of the nail. The lunula is the relatively light-colored space extending from themiddle part of the nail-fold po

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