34G ANATOMY FOR NURSES [Chap. XVIII 



The papillae seem to exist chiefly for the purpose of giving the 

 skin its sense of touch, being always well developed where the 

 sense of touch is exquisite. They are specially large and numerous 

 on the palm of the hand and the tips of the fingers, and on the cor- 

 responding parts of the foot. 



(2) The reticular layer of the corium is a continuation of 

 the papillary layer, there being no real division between them. 

 It is made up of bundles of white fibrous and elastic tissue. 



The derma is attached to the parts beneath it by a layer 

 of areolar tissue, here named subcutaneous, which layer, with 

 very few exceptions, contains fat. The connection in some 

 parts is loose and movable, as on the front of the neck ; in others, 

 close and firm, as on the palmar surface of the hand and the sole 

 of tlic foot. 



Blood-vessels. — The blood-vessels of the skin are found in the 

 derma only. They form a network of capillaries in which the ves- 

 sels are very close to each other, and send branches to the papilhe 

 and glands of the skin. The capillaries of the skin r.re capable of 

 holding from one-half to two-thirds of the blood contained in the 

 body. The amount of blood they contain is dependent on their 

 calibre, and this is regulated largely by the vasomotor nerves. 



Nerves. — The skin is provided with a great variety of nerves. 

 They are classified as follows : — 



(1) Vasomotor nerves, which are distributed in the walls of the 

 blood-vessels. 



(2) Two sets of nerves concerned in the temperature sense, 

 which terminate in the hot and cold spots of the skin. 



(3) The nerves concerned in the sense of touch or pressure. 



(4) Nerves which are stimulated by pain. 



(5) Motor nerves, which are derived from the sympathetic sys- 

 tem and distributed to the glands and the arrector muscles. 



Nearly every nerve centre in the body may be affected by sensa- 

 tions arising in the skin, because of the number of afferent nerves 

 which lead from the skin to centres in the brain and spinal cord. 

 It is for this reason that hydrotherapeutic applications, heat, cold, 

 and counter irritants excite so many and such varied reflexes. 



