920 



TOUCH. 



Richerand, Fodera, and Mayo considered the lingual nerve alone to be the gustatory 

 nerve. Magendie showed, however, that after section of this nerve, the posterior 

 part of the tongue retained its taste-sensation. Panizza (1834) designated the 

 glossopharyngeal as the gustatory, the lingual as the tactile, and the hypoglossal 

 as the motor nerve of the tongue. 



TOUCH. 



TERMINATIONS OF THE SENSORY NERVES. 



The tactile corpuscles, discovered by Meissner in 1852, are ellipsoidal in form, 

 from 40 to 200 , long, and from 60 to 70 fj. wide, and they lie in the papillae of the 

 corium. They are abundant in the palm of the hand, and on the sole of the foot, 

 likewise on the fingers and toes (21 to each sq. mm. of skin, or-io8 for each 400 

 vascular papillae). They are less abundant on the back of the hand and foot, on 



the mammilla, the lips, 

 and the tip of the 

 tongue; rare on the 

 glans clitoridis, isolated 

 on the volar aspect of 

 the forearm (also in 

 anthropoid apes and the 

 raccoon) . 



The tactile corpus- 

 cles have in their in- 

 terior an ellipsoidal 

 inner bulb composed of 

 nucleated epithelial cells. 

 The supplying nerve- 

 fiber loses the sheaths 

 of Henle and of Schwann 

 at the base of the inner 

 bulb, and these in turn 

 surround and enclose the 

 bulb. The nerve-fiber, 

 at first medullated, then 

 nonmedullated, makes 

 spiral turns around the 

 inner bulb, after which 

 it breaks up into fibrils 

 and penetrates the bulb. 

 Here the isolated nerve- 

 fibrils terminate with 

 nodular enlargements 

 between the cells of the 

 bulb. 



Arth. Kollmarm dis- 



-- *-- -o -- " *-"- wji^/uo^ic, c, lin-me corpuscle; /, nerve- 

 deck?) transversely; g, cells of the Malpighian layer (Biesia- 



FIG. 332 r _ r _ t ^ 



fiber passing ( to the tactile "corp"usde; e, tactile corpuscle; /,' nerve- 



, Vascular papilla; b, touch-papilla; c, blood-vessel; d, n 



tinguishes especially on 

 the hand three princi- 

 pal tactile areas: (i) 



thi v S or P usc ! esf J.each 10 mm. of length; ( 2 ) tfhree^iiinTnc2 



the palm behind the mterdigital spaces, where there are from 5.4 to 2.7 

 ptir 0rpUS ? ? I? GVery X ? mm - f len ^ h; (3) the thenar and hypothenar 

 The fiJ tx 6 there . ^ 1 fr m 3-* to 3-5 tactile corpuscles for each mm. 



vvo areas contain also numerous corpuscles of Vater, the third onlv a 



lesl' numerous mmg ^ ^ hand the nervous end-organs are much 



in tL C 3! U8 ? eS f \ ater and Padni (Fi S' 333) are from i to 2 mm. long, and 



fiLTrs and to?, r? eOUS ^ lSS1 f e ' es P e , ciall y on the nerves of the flexor aspect of the 



SVfaLS^nte ! M 00 ' m the mam millary region, in the neighbor- 



the tendons on th I 5 ' On ^ inte Jsseous membrane, on the perimysium, on 



>ns, on the plexuses of the abdominal sympathetic, at the side of the 



