INGBERT, Cutaneous Innervation in Man. 217 
according to my addition of his results) to innervate the 
303,566 mm?. of the dermal surface of the lower limb, or on 
the average one cutaneous nerve fiber for every 3.7 mm”. of 
skin. If my addition of his results be correct this will give 
one cutaneous nerve fiber to every I.g mm?. of skin. 
3. Author's Estimate. Since the cadaver from which the 
spinal roots used in my count of the nerve fibers was that of 
a man weighing 180 lbs. or 81.6 kg., I have made use of 
MEEn’s data, as already given, for the heaviest man measured 
by him, one weighing 78.3 kg. 
A. Body as a whole: 
Area of one side of body, 1,121,740 mm?. 
Deduction for skin of the head innervated by the 
cerebral nerves, (24 of 80,360) 53,573 mm?. 
Corrected area, 1,068,167 mm?. 
Number of cutaneous nerve fibers (79.22% of 653,627) 517,827 
1,068,167+517,827= 2.05 mm?, 
Hence, every cutaneous nerve fiber in the dorsal roots 
innervates on the average 2.05 mm”. of the dermal surface. 
Be) Armi: 
Area of the arm, 199,860 mm?. 
Number of cutaneous nerve fibers in dorsal roots, 
C. V.—Th. I (79.22% of 193,095) 152,970 
199,860+152,970—= 1.30 mm?, 
Hence, every cutaneous nerve fiber in the roots C. V— 
Th. I innervates, on the average, 1.30 mm? of the dermal 
surface of the arm. 
C. Head and Neck: 
Areaof one side of neck, 45,060 mm?. 
Area of one-third of head on one side, 26,786 ‘§ 
Total, 72,446 mm!. 
Number of cutaneous nerve fibers in dorsal roots of 
C. I.—IV (79.22% of 84,404) 66,865 
72,453+66,865= 1.08 mm?, 
Hence, every cutaneous nerve fiber in the dorsal roots of 
C. I—IV innervates, on the average, 1.08 mm’. of the dermal 
surface of the neck, and that part of the head not innervated 
by cerebral nerves. 
D. Leg: 
Area of surface of one leg, 501,680 mm?. 
Number of cutaneous nerve fibers in the dorsal roots 
L. I—Coc. I (79.22% of 258,502) 204,785 
501, 680+ 204,785= 2.45 mm?. 
