CUTANEOUS DISTRIBUTION TO TRUNK AND LIMBS. 



349 



thumb, is supplied by the fifth and sixth cervical nerves ; and the postaxial side, 

 from the little finger to the axilla, by the eighth cervical and first and second dorsal 

 nerves. The seventh cervical nerve does not become superficial on the ventral 

 aspect until the hand is reached, although on the dorsal aspect it appears earlier in 

 the lower external cutaneous branch of the musculo-spiral, but here it is probably 

 distributed to the lower part of the area of that nerve. The digits are supplied 

 by the sixth, seventh, and eighth cervical, and first dorsal nerves, in this order, 

 from the radial (preaxial) to the ulnar (postaxial) side. 



In the lower limb (figs. 222 and 223) the skin of the hip receives its nerves from 

 the lateral cutaneous offsets of the last dorsal and first lumbar nerves, and from the 

 posterior primary divisions of the lumbar and sacral nerves, while the anterior 

 division of the first lumbar nerve reaches the upper part of the thigh in front. The 

 nerves of the preaxial and postaxial borders of the limb are not so readily traced as in 

 the case of the upper limb, owing to the displacement which has taken place with 

 the marked rotation of the lower limb during development, and the great extension 



L.R 



LM 



Fig. 227. THE SEGMENTAL CUTANEOUS AREAS FROM THE SECOND TO THK FIFTH LUMBAR. (Head.) 



The second lumbar ai*ea is marked in cross lines, the third in vertical lines, the fourth with circles, 

 and the fifth with dots. 



of the area supplied by dorsal branches of the limb-nerves, with a corresponding 

 reduction of the ventral area. The preaxial border may be represented by a line 

 following the course of the internal saphenous vein from the groin along the inner 

 border of the sartorius to the knee, and thence along the inner border of the tibia to 

 the ankle and inner border of the foot ; and the postaxial border by a line running 

 from the coccyx along the lower border of the gluteus maximus, thence down the 

 postero-lateral aspect of the thigh to the back of the head of the fibula, and descend- 

 ing along the leg over the external malleolus to the outer border of the foot (Paterson). 

 Along the preaxial border, as thus defined, are the second, third, and fourth lumbar 

 nerves, while along the postaxial border are found the first, second, and third sacral. 

 It will be observed that both of the lines are overstepped to some extent by nerves 

 of dorsal origin, and that the area supplied by ventral nerves is reduced to a strip 

 along the postero-internal part of the thigh, over but not completely covering the 

 hamstring and adductor muscles, and along the back of the leg, but spreading out 



VOL. III., PT. 2. Z 



