PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
77 
direct our attention to the muscles which Cunningham has called the 
“ intrinsic muscles of the foot ” when compared with a similar group of 
muscles in the hand. We find that homologies are best established here 
by referring the muscles of the hand or foot in man to a more gen- 
eralized type and through the arrangement there found we may institute 
comparisons and establish homologies. Cunningham has done this for 
us in his work upon the marsupials. 
One is aided greatly in appreciating the morphological significance of 
these muscles by reference to the conditions obtaining in the foot and 
hand of apes 'and mammals lower in the scale. Reviewing briefly 
Cunningham’s observations on the subject we may first of all state that 
Cunningham^ excludes from the intrinsic group those muscles which in 
man, or as homologous structures in other animals, take origin beyond 
the limits of the foot, and in the human foot he gives the following list 
of intrinsic muscles : 
a. The four short 
muscles of the- 
Great Toe. 
1. 
2 . 
3 - 
. 4 - 
Flexor brevis hallucis. 
Abductor hallucis. 
Adductor hallucis (adductor obliquus.) 
Transversalis pedis (adductor transversus.) 
b. The short mus- 
cles of the 
little toe 
:: 
Flexor brevis minimi digiti. 
Abductor minimi digfiti. 
The occasional opponens minimi dig-iti. 
The occasional abductor ossis metatarsi minimi dig-iti. 
c. The Interossei 
Four dorsal. 
Three plantar. 
In establishing homologies here, we must not place too much import- 
ance upon nerve supply as an aid to correct conclusions. Thus 
Cunningham joins issue with Ruge of Heidelberg, who regarded a 
muscle as the end organ of a nerve, and that, therefore, when a muscle 
altered its position and connections, its origin and typical relations can 
always be identified by its nerve supply. Cunningham admits that 
nerve supply is a most valuable aid to one’s endeavours to discover the 
history of a muscle, but that it is an infallible guide is contrary to fact. 
In this connection Cunningham observes^ that wherever two nerves 
approach one another and reach the confines of their distribution there 
is a tendency to variation in nerve supply. He quotes Brooks’ results as 
to his investigation regarding the variation in nerve supply of the flexor 
brevis pollicis in man, thus — 
1 Loc. cit., (Marsupial Report), p. 48. 
2 Cunning-ham, “The Flexor Brevis Pollicis and the Flexor Brevis Hallucis in Man.’’ Anatomischer 
Anzeiger VII, 1892, p. 206. 
