NERVES OF THE SKIN 



1289 



disturb the metameric arrangement. In the other group the arteries are intrinsically for the 

 supply of other organs but give off small end twigs to the skin, e. g., the arteries to the superficial 

 muscles. 



The arteries enter the corium from the subcutaneous tela, break up into smaller branches 

 anastomose freely and in the deepest layer of the corium form a network, the cutaneous rete 

 (subcutaneous plexus), rete arteriosum cutaneum, from which small branches are given off to 

 supply the fat and sweat glands and also to the i)apillary layer of the corium. Here another 

 network of arteries is formed, the subpapillary rete, rete arteriosum subpapillare. From the 

 subpapillary plexus, minute twigs pass to the papilla, to the hair follicles, and to the sebaceous 

 and sudoriferous glands. 



The cutaneous veins like the arteries may be divided into three groups: (1) small radicals 

 which accompany the corresponding arteries and go to make up veins whose main function is to 

 collect the blood from the muscles; (2) larger branches accompanying the arteries whose main 

 course is in the subcutaneous tela as the inferior superficial epigastric vein; (3) large veins which 

 run in the subcutaneous tela but have a course independent of the arteries such as those seen 

 through the skin on the hands and arms. These large vessels will be foimd described in con- 

 nection with the general description of the veins (Section V). 



Minute venules arise from the capillaries of the papillae, accompany the arteries and form 

 parallel with the surface of the skin a series of closely connected plexuses. Four such plexuses. 



Fig. 1049. — Cutaneous Nerves of the Middle Finger and Lamellous (Pacinian) Cor- 

 puscles (From Toldt's Atlas ) 



i\'^}UF''~'n 



Twig from n. digitalis 

 volaris proprius 



Lamellous(Pacinian'> cor 

 puscles with nerves 



terdigital fold 



Cut edge of skin along 

 mid-hne of dorsal sur- 

 face of finger 



Finger nail 

 Mid-line of volar surface of finger 



more distinct than the arterial, may be recognised in some situations. Of these retia venosa 

 one is situated just beneath the papillae, and another at the junction of the corium and subcu- 

 taneous tela. They receive branches from the fat, hair follicles, and glands, and empty into the 

 large veins of the skin situated in the subcutaneous tissue. 



Lymphatics of the skin. — The cutaneous lymphatic vessels are found in the skin of all parts 

 of the body but are more abundant in certain places. The lymph-vessels of the skin are 

 developmentally among the first lymph-vessels to appear. The larger vessels and glands of the 

 subcutaneous tela will be found described in connection with the general lymphatic system 

 Section VI). In the corium the lymphatics from the papilte form a subpapillary network 

 which opens into a subcutaneous plexus connected with the larger lymph-vessels of the subcu- 

 taneous tela. There are no lymph-vessels in the epidermis, but this is supposed to be nourished 

 by the lymph in the tissue spaces between the cells and these spaces connect indirectly with the 

 lymph-vessels. 



The nerves. — The skin has one of the richest nerve supplies of the body. The nerves are in 

 greater proportion in those parts which are most sensitive. The various skin areas are supplied 

 by specific (segmental) nerves with much greater regularity than in the case of the arteries. The 

 nerves supplying adjoining areas overlap so that there is an intermediate space suppUed by both. 

 The variations consist in an extension of one area and a corresponding contraction of an adjoin- 

 ing area. The distribution of the nerves in the skin shows, especially on the trunk and neck, a 

 marked metameric arrangement. The arrangement of these nerves in the subcutaneous tela 



