262 Ross Granville Harrison 



structures ot the leg are also normal. The only anomaly observed 

 was in the origin of the r. cutaneus cruris posterior. 



The distribution of the n. tibialis is also the same as in normal 

 limbs. First the nerve divides into a smaller r. superficialis and 

 a larger r. profundus (Fig. 10). The latter then gives off a w^ell 

 developed trunk, the r. cutaneus cruris medialis superior which 

 may be traced for some distance down the shank. The two rami 

 of the tibial may be followed into the tarsal region and show nor- 

 mal relations to the muscles (Fig. 11). The ramus profundus 

 passes into the planta pedis in the proximal part of W'hich it breaks 

 up into the four nn. interstitiales plantares. The manner in which 

 these nerves arise is slightly different from the normal as described 

 by Gaupp (Fig. 12). The r. circumflexus could not be traced. 



' — r.prafn.tibialis.- 



r.ciratmfl— 



y^„ 



ji III 



Fig. li Diagram of nen^e supply to the planta pedis: A, according to Gaupp; B,as found in the 

 primary "aneurogenic"' limb in Experiment I. I, II, III, IV, nn. interstitiales plantares. 



The accessory limb receives from the plexus a much smaller 

 n. ischiadicus than the primary limb (Figs. 9 and 10). In addition 

 to this it receives several short twigs that run subcutaneously along 

 the inner posterior surface of the thigh, supplying an area of skin 

 normally innervated by the r. cutaneus femoris posterior and to 

 some extent by the r. cutaneus femoris medialis. The former 

 nerve is small (Fig. 10), and arises in the normal way from the 

 sciatic high up in the thigh. No traces of the n. cruralis have been 

 found. The sciatic gives off a distinct though small ramus pro- 

 fundus posterior, though I have been unable to detect a ramus 

 profundus anterior, which normally also arises from the sciatic. 



In the lower part of the thigh the sciatic nerve divides as usual 



