CHARACTERISTICS OF SKIN 255 



Clinical notes. The insensitive and bloodless character of the epidermis 

 or cuticle is plainly demonstrated in the dressing of a blister, when it is 

 incised to allow the escape of serum which has accumulated between it and 

 the corium or true skin. Again, the fact of the pigment deposit in the deep 

 layers of the epidermis is shown when the blister is on the skin of a colored 

 person; the pigment comes away with the elevated epidermis. 



The surface of the epidermis is continually wearing away and new layers 

 of epithelial cells are exposed, to become dry and scaly, and to be shed in 

 their turn. It varies in thickness according to the degree of friction, or pres- 

 sure, or exposure which it encounters. Witness the palms of the hands and 

 the soles of the feet, the back of the neck and shoulders, the scalp, and in 

 contrast the thin skin of the flexor surfaces of joints, the groins, medial 

 surfaces of limbs, etc. (It is in these latter locations that inunctions are 

 given.) 



The vascularity of the skin is evident from the free flow of 

 blood after the slightest cut. There are two special networks 

 (rete) of capillaries, one just beneath the true skin, and one at 

 the bases of the papillae. 



The elasticity of the skin is demonstrated when a cut is made 

 through the corium. The edges retract and some effort is required 

 to bring them together again. The elasticity is due not only to the 

 elastic fibers in the deep layer of the corium, but to muscle fibers, 

 small though they be. 



The sensibility of the skin is very marked. Nerve-ends exist 

 in the corium for various sensations, a few fibrils being connected 

 with the deep layer of the epidermis. (See The Skin as the Organ 

 of Touch, p. 327.) 



The greater portion of the skin is loosely connected to the parts 

 beneath it by subcutaneous areolar tissue (see p. 5), so that it is 

 movable. When this contains fat it is called the panniculus 

 adiposus. There is no fat under the skin of the scrotum, eyelids 

 or posterior surface of the external ear. 



(The skin of the scalp is not very movable, except as the entire 

 structure is moved by the epicranial muscle.) 



The glands of the skin are in the corium; their ducts pass 

 through the epidermis to open upon the surface. They are of 

 two kinds the sebaceous glands and the sweat glands (sudoriferous 

 glands) . 



The sebaceous glands are found in the skin of all parts of the 

 body except the palms and soles. They are most numerous upon 

 the face. They produce an oily substance called sebum which 



