DISEASES OF THE SKIN. 



By M. R. Tbumbower, D. V. S. 

 [Revised in lf»04 by Leonard Peiiison. B. S.. V. M. D.] 



The skin consists of two parts — a superficial layer, the epidennis, 

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

 corium. 



The epidermis^ cuticle, or scarf skin, is an epithelial structure, 

 forming a protective covering to the coriimi. 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 mucoswn. 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 correspond to the elevations on the dermis. From the cuticle 

 tubular prolongations pass into the sebaceous and sudorific glands; 

 thus the entire surface of the body is inclosed by the cuticle. 



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 of papillae, which are highly 

 sensitive, and consists of a homogenous transparent tissue. The 

 blood vessels form dense capillary plexuses in the corium, terminat- 

 ing 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 

 bulbous extremity, is lighter and softer than the stem, and lodged in 

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

 cutaneous areolae. The follicle is dilated at the bottom to correspond 

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

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