50 PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
adductor brevis, longus and pectineus, extending as high up on the shaft 
as the lower limit of the upper fifth of the bone. The muscle is 
supplied by the obturator nerve. The femoral vessels crossed over 
the anterior surface of the adductor longus near its insertion, and passed 
through the adductor magnus. 
'Yh.Q Adductores femoris are, according to Bischoff, particularly strongly 
developed in all apes. In the Orang he was only able to distinguish the 
adductors longus and magnus ; in all other apes investigated by him, 
including the Gorilla, Chimpanzee and Gibbon, he found the adductor 
group in five muscles, not only the pectineus, adductor magnus, longus 
and brevis, but an additional muscle arising from the crest of the pubis. 
This additional muscle from the crest Duvernoy^ described in the 
Gorilla as a part of the pectineus. 
The floor of Scarpa s triangle. From without inwards, the floor was 
formed by the iliacus, psoas, pectineus and adductor longus. The 
adductor brevis was entirely hidden from view, and there was a triangular 
interval between the psoas and pectineus (with the base uppermost), the 
floor of which was formed by the anterior ligaments of the hip joint 
covering the head of the femur. Passing down in the inner portion of 
the triangle was the femoral vein, lying in direct contact with the ramus 
of the pubis, and the anterior capsule of the hip joint and the femoral 
artery lying upon the inner edge of the psoas. The anterior crural 
nerve was separated from the femoral vessels by an interval of 2 cm. at 
the base of Scarpa’s triangle, and lay upon the iliacus muscle. 
The Psoas arose from the bodies of the lumbar vertebrae, and from 
the transverse processes. A well-developed Psoas parvus lay on the 
anterior aspect of the psoas. It arose from the body of the first 
lumbar vertebra and was inserted into the pubis. Hepburn found a 
psoas parvus in each of the four anthropoids. Fick also found it in 
the Orang and Bischoff in the Gorilla. The Iliacus arose from the 
concavity of the ilium. These two muscles (constituting the ilio-psoas) 
were inserted into the lesser trochanter of the femur. They lay in the 
same plane at the base of Scarpa’s triangle, but afterwards the psoas 
came to lie in front of the iliacus and was inserted into the upper part 
of the lesser trochanter; the iliacus on the other hand, fully four times as 
wide as the psoas, was inserted into the lesser trochanter and into the 
shaft of the femur for i cm. below. 
The Rectus femoris (Plate VI, fig. 8, rect.) arose by a single head from 
Loc. cit., p. 85. 
