PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 



411 



It is evident that D xiii. and L 1 correspond to L 1 and L 2 

 of Man. It is also evident that the branches of the plexus are 

 liable to considerable variation in diflerent animals, and I found 

 some differences on both sides in my own. For example, the 

 obturator nerve came from L 2 and L 3 on the i-ight side, but 

 from L 1, L 2, L 3 on the left. 



The iliO'/iT/pogastric nerve (I-H.N) is the continuation of 

 Dxiii., and it is distributed as in Man. The ilio-inguinal 

 (I-I.N) and genito crural (G-C.jST) nerves are also as in Man ; 

 the former is large. 



The anterior crural nerve (A.O.N) divides into anterior and 

 posterior divisions in the upper part of Scarpa's triangle. The 

 former gi\^es ofl' a cutaneous patellar branch, the cutaneous 

 saphenous nerve and muscular branches to the sartorius, gracilis, 

 and pectineus. The posterior division supplies the quadriceps 

 extensor and the hamstring muscles *. 



The obturator nerve (O.N) divides into inner and outer parts 

 between the inner and outer heads of the adductor brevis. The 

 former emerges to the outer side of the superficial head of the 

 muscle and supplies the pectineus, gracilis, adductor longus, and 

 adductor brevis. The latter emerges to the inner side of the 

 superficial head and supplies the adductor magnus, adductor 

 brevis, and obturator externus. No branch accompanies the 

 popliteal artery. 



The lateral cutaneous nerve (E.O.N) branches off from the 

 anterior crural nerve, and is distributed as in Man. 



The great sciatic nerve (G.S.N) at first supplies the obturator 



* This distribution to the hamstrings was not observed in another Chimpanzee. 



