86 ANATOMY OF THE WOOD RAT 



of its head adjoining. Its tendon, which is the stoutest of 

 all the peronei, passes over the external malleolus and is 

 inserted upon the peroneal process at the base of metatarsus 

 five. 



M. peroneus digiti quarti (figs. 6, 17, 18, 32) usually 

 has origin (as in fig. 17) from a tenuous aponeurosis invest- 

 ing the lateral belly of the peroneus quinti. Occasionally, 

 however, the muscle extends farther proximad and has 

 origin from the head of the fibula superficial to the peroneus 

 quinti. Its tendon passes over the external malleolus and 

 is inserted upon the lateral border of digit four. It is not 

 until its tendon is followed proximad that this muscle is 

 distinguishable from the peroneus digiti quinti. 



In Teonoma the tendon divides into two, a branch ex- 

 tending to either side of digit four. 



M. peroneus digiti quinti (figs. 17, 18, 32) has tenuous 

 origin from the proximal portion of the latero-caudal head 

 of the fibula. Its tendon, passing over the external mal- 

 leolus with those of the other peronei, is inserted onto the 

 lateral border of digit five. 



The peroneal muscles are innervated by the N. peroneus 

 superficiafis. 



D. MUSCLES OF THE FOOT 



The interrelationship of some of the smaller muscles of 

 the sole of the foot is so exceedingly close, and they are so 

 tenuous, that it is not always possible without painstaking 

 microscopical investigation to be absolutely certain in 

 regard to their definition. The exposition of the muscles 

 as here presented has been decided upon only after the 

 dissection of a number of specimens, and the homology of 

 all of them is not certain. 



The muscles of the hind foot that were dissected with 

 satisfactory certainty number eleven, as follows: 



Mm. extensor digitorum brevis abductor digiti quinti 



flexor digitorum brevis flexor digiti quinti brevis 



