112 THE STRUCTURE OF MAN 
Chimpanzee and Gorilla they are not so markedly dorsal in 
position as in Ateles, Inwus, and the Orang; the latter therefore 
are, in this respect, the nearest to Man. 
The adductor hallucis with its caput obliquum and _ trans- 
versum [usually described as a distinct muscle, the transversus 
pedis] originally forms one mass; this points back to the time 
when it was more strongly developed, and when the great toe was 
capable of more extensive movement (cf. ante, p. 85). The fifth 
toe also once moved more freely, as 1s indicated by the opponens 
minimi digiti, which is only secondarily differentiated during 
embryonic life from the mass of the flexor brevis minimi digiti. 
The former muscle is, comparatively speaking, much stronger in 
embryonic life than later, when it may entirely disappear.’ 
MUSCLES WHICH APPEAR OCCASIONALLY, AND MAY BE 
CONSIDERED ATAVISTIC 
In dealing with this group of muscles, we may confine our- 
selves to those which point back to lower grades of organisation, 
through which the ancestors of Man may have passed phylogene- 
tically. I wish to insist on this, since nothing is gained by 
simply labelling muscles “theromorphic,” and since, in my 
opinion, in dealing with such muscles, Testut and certain other 
authors have exceeded the bounds of moderation. 
One of these apparently atavistic muscles, the cleido-occipitalis, 
which forms a connecting tract between the trapezius and the 
sterno-cleido-mastoid, has already been mentioned (ante, p. 102). 
To the same category belong certain muscle bundles which here 
and there partly fill up the interval between the pectoralis 
major and the latissimus dorsi. A typical example of these has 
been lately described by my pupil Endres (Anat. Anzeiger, Bd. 
vill. p. 387), the morphological significance of the so-called 
Langer’s arch being incidentally discussed. 
A muscle which very rarely occurs in Man is the latis- 
simo-condyloideus (dorso-épitrochlearis of French authors), an 
appendage of the latissimus dorsi, branching off from the 
latter shortly before it is inserted into the humerus. From 
1 The opponens minimi digiti seems to attain development only in the Chim- 
panzee among Anthropoids. [Incidentally to this topic and to that of the reduc- 
tion and co-ossification of the penultimate and terminal phalanges of the little 
toe (cf. ante, p. 89), it is interesting to observe that the muscles of the little toe 
are more reduced in the higher Apes than in Man. ] 
