J. Plajfair McMurricli CI 



obliquely inwards, giving ofE branches to the tibialis posticus (TP), the 

 j.ronator tibia} (PT) and the flexor digitorum tibialis (FT), and then 

 continued its course downward between the tibialis posticus and the 

 flexor digitorum fibularis, without supplying either, and terminated near 

 the ankle joint, apparently in the periosteum of the lower part of the 

 tibia. The lowest of the branches which passed to the pronator tibia? 

 could be traced downwards in the muscle almost to the ankle joint and 

 seemed to end there in periosteal branches to the lower end of the fibula. 



The branch to the plantaris (pi) might be described as arising from 

 the internal plantar nerve (IP) but with this exception neither the inter- 

 nal nor the external (EP) plantar nerves takes any part in the innerva- 

 tion of the muscles of the crus. After they have passed into the foot 

 the external plantar gives off a branch, which passes mainly to the 

 abductor minimi digiti, but also gives two twigs to the flexor digitorum 

 accessorius. 



In the mouse (Fig. 14) the internal gastrocnemius is supplied by a 

 branch (GI) given off above the level of my highest section. The inter- 

 nal popliteal descends between the two gastrocnemii, gives off branches 

 to the gastrocnemius externus (GE) and to the popliteus (P), and 

 divides, opposite the knee joint, into three branches, two smaller ones 

 and one large one. The latter (tp) is comparable to the posterior tibial 

 nerve of human anatomy in many respects, although it takes no part in 

 the innervation of the crural muscles but descends unbranching to behind 

 the inner malleolus, where it divides into the external and internal 

 plantar nerves (EP and IP), the former sending a branch to the 

 flexor accessorius. 



Of the two smaller branches, one (Fig. 14, FF; Fig. 10, ff) shortly after 

 its formation gives branches to the plantaris (pi) and the soleus (5), but 

 passes mainly to the flexor fibularis. The other smaller branch (Fig. 10, 

 rp) gives off early in its course a branch to the popliteus (Fig. 14, P) and 

 probably supplies the flexor tibialis also, although neither one nor the 

 other of my series of sections permitted of perfect certainty of this point 

 in this form. The branch then descends between the flexor flbularis and 

 the tibialis posticus, giving off a branch to the latter, and, passing more 

 deeply between the two muscles as it descends, finally rests upon the 

 interosseous membrane and seems to terminate in the periosteum of the 

 lower part of the fibula. 



In the cat the arrangement of the nerves is in general the same as in 

 the mouse. A branch is given off from the sciatic, before its division, 

 to the internal gastrocnemius and another from the internal popliteal 

 soon after its formation passes to the external gastrocnemius. A little 



