36 
PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
with the flexor profundus digitorum. Schulze^ has described a similar 
condition. Turner records one case in which the bond of union passed 
in the opposite direction from the flexor profundus to the flexor longus 
pollicis. Wagstafife^ has described a case in which a muscle arose like 
the flexor longus pollicis, but was inserted into the deep flexor tendon 
to the index finger and was connected also with the fibrous structures 
about the wrist ; there was also a tendon on the palmar aspect of the 
first and second phalanges of the thumb, which, however, was attached 
above to the head of the metacarpal bone. Gegenbaur^ has recorded a 
case in which the flexor longus pollicis was absent from the thumb of 
man — the muscle had evidently fused with the flexor for the index 
finger; the thumb itself was very rudimentary, and presented an appear- 
ance very similar to that found in the apes. The abnormality was 
found on the left side of the body, the right flexor longus pollicis being 
normally developed. The importance of these facts concerning the 
absence of the flexor longus pollicis in the ape and its existence as a 
strongly developed structure in man is emphasized by Testuf^ when he 
says, “ De toutes les dispositions anatomiques qui dififerencient actuelle- 
ment I’homme des autres Primates, Tune des plus importantes est, sans 
conteste, la presence chez Thomme, I’absence chez les Singes d’un long 
flechisseur propre du pouce, completement distinct des autre flechis- 
seurs.” Testut holds that the flexor longus pollicis is present in the 
apes, arising as it does in man, but the peculiarity in apes is that it fuses 
with the flexor profundus and loses the characteristic individuality 
which is found in man where it passes as a distinct and separate muscle 
to the thumb. Testut himself, after examination of a large number of 
subjects, had never found the flexor longus completely absent from the 
thumb of man. 
Gratiolet and Alix^ describe a rudimentary muscle in the Chim- 
panzee arising from the ligaments over the anterior aspect of the carpus 
and inserted into the last phalanx of the thumb. 
The Pronator quadratus consisted of a number of muscle fibres 
passing transversely from the radius to the ulna ; in the upper part of 
1 F. Eilhard Schulze, “Die Sehnenverbindungf in der Planta des Menschen und der Saugethiere.” 
Zeitschrift fiir Wissenschaftliche Zoologie, Bd. 17, 1867, p. i . 
2 W. W. Wagstaffe, “ Partial Deficiency of the Tendon of the Long Flexor of the Thumh,” Journ. of 
Anat. and Phys., Vol. VI, 1872, p. 212. 
3 C. Gegenbaur, “ Ein Fall von mehrfachen Muskelanomalien an der oberen Extremitat,” Virchow’s 
Archiv fiir Pathol. Anat. und Phys., Vol. XXI, 1861, p. 382. 
4 L. Testut, “ Le Long Flechisseur Propre du pouce chez Thomme et chez les Singes,” Bulletin de la 
Soc. Zool. de France, Vol. VIII, 1883, p. 164. 
5 Loc. cit., p. 172. 
