THE DERMA 203 



divisible into two strata, a deeper reticular layer in which coarse 

 fibre bundles interlace to form a loose connective tissue network, 

 and a superficial papillary layer in which the finer bundles of con- 

 nective tissue form a more closely meshed network. 



The Papillary Layer. The surface of the papillary layer pre- 

 sents numerous conical elevations, the papillce of the corium, which 

 project into corresponding cup-shaped cavities in the under sur- 

 face of the epidermis. Many of the connective tissue papillae 

 contain tactile end organs (touch corpuscles of Meissner), and 

 terminal filaments of the nerve fibres. They may therefore be 

 regarded as the special organ of tactile sensation. Other papillae 

 contain no touch corpuscles but are richly supplied with capillary 

 blood vessels. Two types are thus distinguished, the tactile papillce 

 and the vascular papillce. 



Papillae are most abundant in the palms of the hands and the 

 soles of the feet, where they are mostly arranged in rows which 

 are responsible for the fine lines and ridges visible to the naked 

 eye. In other portions of the body they are less numerous and are 

 often less regularly disposed. 



The papillary layer consists entirely of white fibrous and elastic 

 connective tissues which form a supporting membrane for the 

 finer branches of the cutaneous blood vessels and nerves. The 

 elastic tissue supplies a rich network of fine fibrils to all portions 

 of the papillary layer, and just beneath the epidermis it forms a 

 delicate elastic membrane whose fibres intermingle with the hya- 

 line cuticular deposit of the columnar epidermal cells to form a 

 firm resistant basement membrane. Many of the elastic fibres of 

 the papillae, especially the more superficial ones, pursue a peculiar 

 archiform course from the base to the apex of the conical papillae. 

 In this way they surround and inclose the centrally situated capil- 

 laries and the tactile corpuscles of the papillae. 



The Reticular Layer. The deeper portion of the corium con- 

 sists of interlacing bundles of connective tissue fibres which form 

 a dense reticulum. These bundles are much coarser than those 

 of the papillary layer with which they are imperceptibly blended. 

 The reticular layer contains the larger blood vessels of the corium, 

 many small nerve trunks, the ducts and parts of the secreting 

 portions of the sweat glands, the more superficial sebaceous glands, 

 and many of the smaller hair follicles. Pacinian corpuscles and 

 nerve end organs of Ruffini are also found in this layer. 



The skin of the face contains many striated muscle fibres 



