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The gastrocnemius internus (Pl. XIV. x) has two powerful heads, one from the femur, 
the other from the tibia; the first (x)+ arises fleshy from the internal condyle of the 
femur, expands as it descends, and receives additional fibres from the lower edge of the 
accessorius semitendinosi, About one-fifth down the tibia this muscular origin in the 
right leg terminated in a flattened tendon (x*), which became attached to the inner 
side of the tibial portion of the gastrocnemius internus (n**). In the left leg the tendon 
soon divided ; one portion passed to the soleus, the other went to join the tibial portion 
of the gastrocnemius internus. The second head, which is separated from the preceding 
by the insertion of the semitendinosus, arises partly from the internal and anterior part 
of the strong fascia of the knee-joint by short tendinous fibres, which almost immediately 
become fleshy, and partly from a well-defined triangular surface (r**) on the inner and 
anterior aspect of the head of the tibia: the fleshy fibres converge, receive the tendinous 
slip from the femoral portion, and end on the inner side of the muscle in a strong flat- 
tened tendon, about two-thirds down the leg: this joins the tendon of the gastrocnemius 
externus (nk e), and is inserted as described above. 
Soleust (Pl. XIV. s).—This is a slender flattened muscle arising from the posterior 
part of the head of the tibia, the tendon of which joins that of the gastrocnemius internus, 
behind the tarsal joint. 
The Flexor perforans digitorum (Pl. X. XI. XIV. 1) lies immediately anterior to the 
external gastrocnemius; it arises fleshy from the outer condyle of the femur, below the 
tendinous origin of that muscle, and terminates in a slender flat tendon half-way down 
the leg. Its tendon (1) glides behind the tarsal joint through the sheath of the gastro- 
cnemius, expands beneath the metatarsus and bifurcates, sending its smallest division to 
the inner toe, and its larger one to blend with the tendon of the peroneus longus. 
Flewor perforatus of the outer toe (Pl. X. XI. XIV. 2).—This arises by.very short ten- 
dons from the proximal end of the fibula, and from the ligament forming the bicipital 
pulley ; it continues to derive a thin stratum of fleshy fibres from the fascia covering the 
anterior surface of the muscles of the leg ; the fleshy fibres terminate half-way down the 
leg in a flattened tendon, which, after entering the gastrocnemial sheath, pierces the 
tendon of the first perforatus of the middle toe, then runs forward to the outer toe, ex- 
pands into a thick ligamentous substance beneath the proximal phalanx, and sends off 
two tendinous attachments on each side, one to the proximal, the other to the second 
phalanx, and is continued to be finally inserted into both sides of the third phalanx. 
Flexor perforatus digitorum (Pl. XI. XIV. 3, 4, 5,6) is the strongest of the three ; it 
arises fleshy from the posterior part of the distal extremity of the femur, above the ex- 
ternal condyle (Pl. XI. 4), and also by a distinct flattened tendon (6), one inch in length, 
+ This is described as the soleus in the Cassowary, by Prof. Mayer, Joc. cit, p. 15, but the origin of this muscle 
is not extended in other animals above the knee-joint. 
t This is described as the plantaris in the Cassowary, by Prof. Mayer, loc. cit. p. 14, but the normal origin of 
that muscle should be sought for above the knee-joint. 
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