70 
PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
The opponens hallucis is not always present in the Orang, and often- 
times it is extremely weak. Testut states that an opponens is sometimes 
found in man. “ On trouve quelquefois, au-dessous de lui (i.e., brevis 
hallucis), quelques fibres profondes, inserees sur le metatarsien et con- 
stituant un veritable opposant du gros orteil, homologue de I’opposant du 
pouce ; mais ce muscle est rarement bien differencie.”^ 
The Adductor obliquus hallucis and the Adductor transversus hallucis 
had a continuous origin from the bases of the third, fourth and fifth 
metatarsal bones, from the fascia over the interossei muscles, from the 
sheath of the peroneus longus and from a fibrous arch extending from 
the base of the fifth metatarsal to the middle of the second metatarsal 
bone. These muscles are inserted into the whole of the fibular and the 
greater part of the plantar aspect of the base of the proximal phalanx. 
The transverse and oblique muscles could be readily separated from one 
another, and a third portion was defined which had an insertion into the 
lower border of the first metatarsal bone. This, no doubt, represented 
the “second opponens” described by Brooks as derived from the 
adductor obliquus. 
Fick^ holds that the main function of the adductor hallucis in the 
Orang is opposition and not adduction. Brooks^ describes in the Orang 
a portion of the adductor obliquus (inseparable at its origin from the 
rest of that muscle), which ended in a rounded tendon and which passed 
between the two heads of the flexor brevis, and running along in a well 
marked sheath in the middle line of the digit, was inserted into the base 
of the ungual phalanx. It took the place of the absent long flexor 
tendon. This may be compared with the description of similar con- 
ditions found in the hand of anthropoids and already noted (p. 44). A 
somewhat similar tendon is described by Gratiolet and Alix^ in the 
Chimpanzee and the Orang ; the muscle arose along with the adductor 
transversus, and, passing over the proximal phalanx, was inserted into 
the base of the last phalanx. It was looked upon by these authors as 
representing the long flexor. BischoIT found in the Frankfort Orang on 
the left side a small tendon which in course and insertion corresponded 
to the flexor longus hallucis, but it arose from the fascia over the ball of 
the great toe.® 
The tendency for intimate connection of the adductor hallucis with 
1 Loc. cit., Vol. I, Pt. 2, p. 882. 
2 Loc. cit. I, p. 47. 
3 Loc. cit., p. 87. 
4 Loc. cit., p. 102. 
5 Loc. cit. I, p. 234. 
