6o 
PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
The Peroneus longus arose from the head of the fibula on its outer 
aspect,' and from the intermuscular septum, the line of origin being 
2 cm. long. The musculo-cutaneous nerve passed between the upper 
part of the muscle and the fibula ; the muscle became tendinous at the 
junction of the lower and middle thirds of the leg ; the tendon grooved 
the cuboid bone, and passing inwards across the sole of the foot, it was 
inserted into the base of the first metatarsal bone at the junction of the 
plantar and outer margins. The peroneus longus had also a very defin- 
ite slip of insertion into the fifth metatarsal bone. Fick^ also describes 
this double insertion in the Orang. 
The Peroneus brevis arose over 4.5 cm. of the outer side of the fibula, 
along an oblique line extending from above and in front, downwards 
and backwards to the posterior aspect of the bone immediately above 
the external malleolus. The upper limit of its origin was as high as the 
junction of the upper and the middle thirds of the bone. It was 
inserted into the base of the fifth metatarsal bone, and into a tendinous 
arch extending from the os calcis to the base of the fifth metatarsal 
bone (“ abductor ossis metatarsi quinti ” of Huxley). This extensive 
and strong insertion band of the muscle gives rise to certain fibres of 
the abductor minimi digiti. Some of the tendon fibres of the peroneus 
brevis were directly continuous with the peroneus longus tendon in the 
sole. 
Bischofif,^ in comparing the peroneus longus in man and apes, 
refers to the fact that on account of the saddle shape of the joint 
between the cuneiform and the first metatarsal, and of the more isolated 
position of the great toe in the ape as compared with man, the peroneus 
longus in the ape acts in bringing the great toe into opposition with the 
other toes, whilst in man it acts on the anterior part of the foot as a 
whole. 
Bischoff describes another muscle in the ape, the Peroneus 
parvus.^ This muscle, he says in lower apes exists as a fourth per- 
oneus. It lies between the longus and brevis arising from the fibula. 
It becomes tendinous in the leg, and extending to the outer margin of 
the foot passes to the first phalanx of the little toe, where it unites with 
the tendon of the flexor digitorum communis longus. This muscle, 
Bischoff states, evidently corresponds with the well-known tendon which 
almost always in man goes from the tendon of the peroneus brevis and 
1 Loc. cit. I, p. 42. 
2 Loc. cit. I, p. 229. 
3 Loc, cit. I, p. 230. 
