THE SKIN 325 



arteries coursing through the subcutaneous tissues. 

 These form minute capillary plexuses which send off 

 branches to form other plexuses in the corium and 

 papillary layer; from the latter branches pass to the 

 papilla, sweat glands, sebaceous glands, fat, and hair 

 follicles. 



The Appendages of the Skin. They are the nails, 

 hairs, the sudoriferous or sweat glands, and sebaceous 

 glands. 



The Nails. These are flattened, elastic structures 

 of a horny texture, placed upon the back surface of 

 each distal extremity of each finger and toe. The 

 nail is implanted by means of a portion called the 

 root, within a groove in the skin. The rest of the con- 

 vex surface of the nail is called the body. Beneath the 

 root and body is a portion of the cutis called the 

 matrix. This is the part from which the nail grows. 

 The white, crescentic-shaped area of the nail seen 

 behind the matrix and above the root is called the 

 lunula. Its color is due to its being less vascular 

 compared to the remaining portion of the nail. The 

 nail can be injured, and if any cells of the Malpighian 

 layer remain, a new nail will develop from these 

 cells. 



The Hairs. They are found in certain regions of 

 the body. They act as a protection to the part; pre- 

 vent friction; prevent foreign bodies from entering the 

 organs they protect, as the eyes, nose, etc. We speak 

 of hairs of the head, of the eyebrows, of the axilla, of 

 the eyelids, of the nose, of the pubes, and of the skin. 

 They vary much in length, thickness, and quality. 

 In some individuals the hair is straight, in others 

 curly. Hairs usually are oblique to the surface from 

 which they arise. 



Hairs are modifications of the skin (epidermis) and 

 consist essentially of the same structure as it. Hair 

 consists of the root, the part implanted in the skin; 



