THE SENSE OF TOUCH 391 



THE SENSE OF TOUCH 



The structures essential to the appreciation of the 

 sense of touch are the skin and mucous membrane 

 of the mouth, etc., the end-organs therein and the 

 afferent nerves which convey the nerve impulses by 

 pathways through the cord and brain to the cells in 

 the tactile area of the cerebrum which are located in 

 the parietal lobes. 



The end-organs are the highly specialized organs 

 found not only in the skin, but in other sense organs. 

 They are the sensitive bodies intervening between 

 the surface coming in contact with the skin, etc., and 

 the terminal filaments of afferent nerves. They are 

 more sensitive than the terminals of afferent nerves 

 and receive specific stimuli which excite them to 

 activity; and they in turn transmit the impulses to 

 the afferent nerves. However, these end-organs are 

 usually spoken of as the terminations of afferent 

 nerves. 



Classification of End-organs. (1) Free Endings. 

 Club-shaped processes found in and among the cells of 

 the epidermis (upper layer of skin) ; they are termina- 

 tions of minute fibers of afferent nerves. 



2. Tactile Cells. They are oval, nucleated bodies 

 found in the deep layer of the epidermis. They are 

 embraced by a crescentic-shaped body (tactile disk) 

 which is directly connected with the afferent nerve. 



3. The Corpuscles of Meissner and Wagner. These 

 are found in the papillae of the derma (deep layer of 

 skin), especially in the palm of the hand and finger 

 tips. They are bodies which consist of numbers of 

 tactile disks surrounded by connective tissue and are 

 in connection with the terminals of afferent nerves. 



4. Hair Wreaths. They are minute nerve fibers, 

 consisting of a whole axis-cylinder, which surround 

 the hair follicle just beneath the opening of the seba- 



