NEKVE SUPPLY 291 



vessels. Branches from this plexus pass to the papillary layer, where they 

 form a second (subpapillary) plexus from which terminal arteries are 

 distributed to the capillaries of the papillae. 



The distribution of the veins is similar to that of the arteries. The 

 primary plexus is found in the papillary layer; occasionally a second 

 plexus immediately underlies the first, and from these, venules pass to 

 the deeper part of the corium, whence after free anastomosis they pro- 

 ceed to the subcutaneous tissue, collecting on the way the venules return- 

 ing from the hair follicles and secreting glands, and from the subcuta- 

 neous connective tissue. The very rich capillary network in the papilla 

 of the hair bulb is worthy of special mention. 



The lymphatic vessels of the skin begin as a terminal lymphatic 

 plexus in the corium, which collects the lymph from the tissue spaces 

 of both derma and epidermis. The vessels of this plexus communicate 

 with a subcutaneous lymphatic plexus of larger vessels which follow the 

 course of the blood-vessels on their way to reach the neighboring groups 

 of superficial lymph glands. 



NERVE SUPPLY 



The skin is abundantly supplied with large nerve trunks, both sympa- 

 thetic and cerebrospinal (sensory), which find their way along the sub- 

 cutaneous fat and send branches directly to the larger blood-vessels, 

 the hair follicles, the sebaceous and sudoriparous glands, to the cor- 

 puscles of Pacini, Ruffini, and Golgi-Mazzoni, and to the end bulbs of 

 Krause, which lie in the connective tissue. 



In the cutis vera the nerve trunks form a plexus of delicate fiber 

 bundles in the reticular layer, with a secondary, more closely meshed 

 plexus of finer nerve bundles in the papillary layer. From these 

 plexuses fibrils are distributed to the smaller blood-vessels and to the 

 papillae, where many end in tactile corpuscles. Other fibrils penetrate 

 the epidermis, terminating as naked fibrils or on tactile cells. 



In the region of the hair follicle small branches form a network 

 of fibrils in the dermal root sheath. Branches (pilomotor nerves) are 

 also distributed to the arrectores pilorum muscles. 



In the sudoriparous glands the nerves form a fine plexus about the 

 membraua propria (epilamellar plexus), from which naked axis cylin- 

 ders penetrate the basement membrane and terminate between the 

 secreting cells. 



