480 DR. R. W. SHUFELDT ON [Nov. 16, 
After we have cut away the ¢ibialis anticus, we find another, and 
only one other, muscle occupying the anterior aspect of the tibia. 
This is the extensor longus digitorum. 
The extensor longus digitorum (Plate XLY. fig. 1, e./.d) arises 
from the anterior aspect of the in-half of the tibial shaft as high up 
as the ¢idialis anticus muscle, which covers it; it also arises from a 
tense fascia which comes off from the lower free edge of the pro- 
cnemial crest of the tibia; and finally from a longitudinal line ex- 
tending obliquely down the front of the shaft of the tibia to its 
lower third. This obliquity finally brings the tendon in which the 
extensor longus digitorum terminates to the middle line. 
Just above the condyles of the tibia, it here passes through the 
little bony bridge ; emerging from which it crosses the ankle-joint in 
front, then passes down the anterior aspect of the tarso-metatarsus 
bone, overlying the short extensor. At the upper end of this last- 
named bone, and over the ankle-joint, this tendon is firmly bound 
down by a fibrous fascia. In some birds we know a special bony 
span exists for it on the upper part of the tarso-metatarsus, as in 
certain Owls. When the tendon of this muscle arrives at the 
anterior aspect of the trochlew of the distal end of the tarso-meta- 
tarsus, it expands and bifurcates. The tendinous expansion becomes 
more or less attached to the underlying tissues, while each bifur- 
cation passes one over the second, and the other over the third toe, 
for their entire lengths, to become inserted into the upper points of 
their ungual phalanges. 
Now from the side of the tendon that goes to the third toe 
another slip is differentiated off in a very peculiar manner, owing to 
the reversion of the toe in question. For it not only passes over the 
top length for insertion of this fourth digit, as in the case of the 
others, but its slip also splits off to make a separate insertion at the 
extremity of the basal phalanx of the third digit. I have had the 
opportunity of dissecting three feet, with the view of studying this 
point, and I find it to obtain in all of them. 
The extensor brevis digitorum (Plate XLV. fig. 1, e.6.d). Thisisa 
muscle I find that, in common with many other authors, I have de- 
scribed in my MSS. as the extensor hallucis brevis, from the fact that 
its tendon goes to the hallux alone. But here, so extraordinary is its 
development, that no such term would be either adequate or appro- 
priate. 
Even here the short extensor of the hallux has a certain amount 
of individualization, though it is not fully differentiated from the 
other part of this extensor brevis. It, however, is not attached 
more than halfway down the anterior aspect of the shaft of the 
tarso-metatarsus, at which point it terminates in a delicate thread- 
like tendon; this passes directly over the upper border of the 
accessory metatarsal, and along the top of the basal joint of the 
hallux, to become inserted in the usual manner in the base of the 
claw-joiat. Now the remainder of the ewtensor brevis digitorum is 
attached down the shaft of the tarso-metatarsus, as far as the distal 
trochlez ; the outer portion of it developing a tendon about halfway 
down, which is concealed by the carneous fibres which overlie it. 
nie Y 
