240 Journal of Comparative Neurology. 



2. Comparison of the areas for the cutaneous and for the mus- 

 cular fibers to the thigh. 

 A second interesting relation is brought to view by a com- 

 parison of the areas for the cutaneous and for the muscular 

 fibers to the thigh. 



In Table XIII, the measurements for all the cutaneous fibers 

 to the thigh are summarized. Both the crural and the sciatic 

 nerves convey cutaneous fibers to the thigh. The ramus cuta- 

 neus femoris lateralis is the first branch of the crural nerve, 

 and contains all the crural cutaneous thigh fibers. This branch 

 innervates the ventral aspect of the thigh. 



The ramus cutaneus femoris posterioris and the ramus 

 cutaneus femoris medialis are the ramifications of the sciatic 

 nerve which carry cutaneous fibers to the thigh. The ramus 

 cutaneus femoris posterioris is given off with the sciatic muscular 

 branch to the M. pyriformis, and innervates the dorsal aspect 

 of the thigh. The ramus cutaneus femoris medialis is the ter- 

 minal twig of the posterior division of the ramus profundus pos- 

 terior and innervates a portion of the median aspect of the 

 thigh. The point of section of the latter is not indicated in 

 Figure II, but can be identified in Figure .1 by the designation 

 S 6 b 2) s- The section was accomplished at the point at which 

 the twig, after piercing the M. gracilis minor, passes through the 

 subcutaneous tissue, and just before it separates into its cuta- 

 neous ramifications. 



The crural cutaneous fibers to the thigh have been studied 

 in connection with Table IX, where the average area for each 

 fiber of the crural nerve was computed. An average area was 

 there determined of 137 square micra for each crural cutaneous 

 fiber to the left thigh, and 144 square micra for each crural 

 cutaneous fiber to the right thigh. 



The first of the sciatic cutaneous branches to the thigh, 

 ramus cutaneus femoris posterioris, contains for the left thigh 

 169 fibers in an area of .02 of a square millimeter, and furnishes 

 an average area of 114 square micra for each fiber. The same 

 branch for the right leg furnishes an average area of 1 10 square 

 micra for each fiber. 



