336 MICROSCOPIC ANATOMY OF THE ORGANS. 



quadrangular. Passing deeper, the veins form a third network 

 in the lower part of the corium, with large irregular meshes. 

 The fourth plexus is formed between the corium and subcutis. 

 These are all shown in the reconstruction taken from the work 

 of Spalteholz (Fig. 257). The circular muscle layer disappears 



FIG. 257. 



1 Venous nctiroi-L 



2 Venous network .^r-r^ 

 f$*bpapiUary. 



'.', ]'t'nonx 



network 





Eeconstruction of blood-vessels of the skin of the human foot. (Spalteholz.) 



in the arteries in the middle of the cutis, and in the veins ap- 

 pears in the fourth plexus, where valves also are found first. 



The lymph-vessels form a fine, close plexus spread out in 

 the stratum papillare, from which loops are sent to the papillae. 

 The larger vessels passing into the depths from this plexus 

 anastomose in the stratum subcutaneum, to give rise to a 

 second coarser network. 



Nerves are present everywhere in the skin, while certain 

 regions are supplied specially (e. g., soles of the feet, palms of 

 the hands, external genitals). Numerous forms of nerve- 

 endings are present. We find free intra-epithelial nerve- 

 endings, and Merkel's tactile corpuscles in the epidermis ; 

 Meissner's tactile corpuscles, and end bulbs in the papillae; 

 and Vater-Pacinian, Ruffini's, and other corpuscles in the 

 subcutis. 



