CHAPTER XI 



THE SKIN 



The skin, or integument, consists of an outermost ectodermal layer 

 of stratified squamous epithelium, the epidermis (cuticle), and a sub- 

 jacent mesodermal layer of dense connective tissue, the corium or derma 

 (derma vera, cutis vera), homologous with the tunica propria of the 

 mucous membranes. The corium contains the nerves and the nerve end 

 organs of special sense, and rests upon a subcutaneous layer of areolar 

 and adipose connective tissue which, blending with fascia or periosteum, 

 unites the skin to the underlying muscles and bones. 



The skin serves a composite function : protection, regulation of body 

 temperature, tactile sensation, and excretion. Its excretory role is in 

 fact accessory to the kidney. 



The skin is typically a stratified organ, and for convenience of 

 description may be divided into the following layers : 



SKIN. 



I. Epidermis. 



'1. Scaly layer. 



2. Flattened cell layer. 



3. Eleidin-containing layer; 



stratum lucid um 



4. Granular layer; stratum^ 



granulosum. 



5. Prickle cell layer. 



6. Cylindrical cell layer. 

 1. Papillary layer. 



J3. Eeticular layer. 

 III. Subcutaneous tissue. 



Horny layer; 

 stratum corneum. 



Germinal, Mal- 

 pighian or mu- 

 cous layer. 





II. Derma. 



THE EPIDERMIS 



The epidermis (cuticle) or scarf skin serves for the protection of 

 the more sensitive corium or 'true skin/ It is formed by a dense layer 

 of stratified epithelium and varies in thickness in different portions 



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