400 



HITCHCOCK'S ANATOMY 



others, since some portions of the skin are more fully crowded 

 with nerve fibers than others. We are conscious of resistance 

 if we place a substance in contact with any part of the body ; 

 and although we are able with the tips of the fingers to tell, 

 whether a body, which is pressed on them, is circular or rect- 

 angular, yet we can not with certainty decide the same thing, 

 if the substance be pressed upon any other part of the body. 



734. The Direct Instruments of Touch— The direct in- 

 struments of sensation are minute loops of nerve fibers from 

 the posterior roots of the Spinal Column, lying in the true 



Fig. 365. 



Nerves of Sensation at the Extremity of the Human Thumb. 



skin, which are covered only by the Epidermis, as is seen in 

 Fig. 365. These nerves of sensation are never known to ter- 

 minate in a free extremity, but always in loops; and in the 

 hand and foot are associated with the Pacinian Corpuscles, 

 described under the nervous system. 



735. P a p i 1 1 sc — Those 

 parts of the skin which are 

 the most sensitive, are cov- 

 ered with minute projections 

 called Papillse, which seem 

 to be mere elevations beyond 

 the general surface of the 



Fig. 366. 



Papillae of the Palm of the Hand. 



What is said of the whole cutaneous surface ? 734. What are the immediate instru- 

 ments of touch? How do the sensitive nerves always terminated T35. Describe the 

 papillaB. 



