DISEASES OF THE SKIK 



By M. E. Trumbower, D. V. S. 

 [Revised in 1904 by Leonard Pearson, B. S., V. M. D.] 



The shin consists of two parts- — a superficial layer, the epidermis, or 

 cuticle; and the deep, or true, skin, the dermis, cutis vera, or corium. 



The epidermis, cuticle, or scarf skin, is an epithelial structure, form- 

 ing a protective covering to the corium. It varies in thickness, is 

 quite insensible and nonvascular, and consists of a sheet of cells. 



The epidermis is divided into a firm and transparent superficial and 

 a deep soft layer. The latter is the rete mucosum, in whose cells the 

 pigment exists which gives color to the skin. The deep surface of the 

 epidermis is accurately molded on the papillary layer of the true skin, 

 and, when removed by maceration, presents depressions which, corre- 

 spond to the elevations on the dermis. From the cuticle tubular pro- 

 longations pass into the sebaceous and sudorific glands; thus the 

 entire surface of the body is inclosed by the cuti3le. 



The dermis, or true skin, is vascular and highly sensitive, contain- 

 ing the tactile ends of the nerves of touch. It is covered by epi- 

 dermis, and attached to the underlying parts by a layer of areolar 

 tissue, which usually contains fat. The cutis consists of fibro-areolar 

 tissue and vessels of supply. It is divided into two layers, the deep 

 or true corium and the upper or papillary. The corium consists of 

 strong interlacing fibrous bands, chiefly white; its meshes are larger 

 and more open toward the attached surface, giving lodgment to the 

 sweat glands and fat. The papillary, or superficial, layer is formed of 

 a series of small conical eminences or papillfe, which are highly sen- 

 sitive, and consist of a homogenous transparent tissue. The blood 

 vessels form dense capillary plexuses in the corium, terminating by 

 loops in the papillae. The papillary nerves run in a waving manner, 

 usually terminating in loops. 



Hair is an appendage of the skin and forms its external covering. 

 It is a special modification of epidermis, having the same essential 

 structure. It consists of a root, shaft, and point. The root has a bulb- 

 ous extremity, is lighter and softer than the stem, and lodged in a 

 recess or hair follicle, which may either be in the corium or subcuta- 

 neous areolae. The follicle is dilated at the bottom to correspond with 

 the root bulb, and the ducts of one or more sebaceous glands open into 

 it. At the bottom of each follicle is a conical vascular papilla, similar 

 in every respect to those on the surface of the dermis; this papilla fits 

 into a corresponding depression in the root of the hair. The shaft con- 

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