374 THE MUSCLES. 



the long lateral peroneus, which it passes under ami crosses, in descending to the phalanges 

 of the external digit, where it is united to the tendinous branch of the common extensor 

 belonging to this digit. 



The inferior fasciculus has its origin on the anterior border and external aspect of the 

 peroneus, by penniform fibres, which join a short, but more voluminous tendon than that of 

 the preceding fasciculus. This tendon, with tlie last, enters the posterior groove in the fibula, 

 and is attached, by its inferior extremity, to the upper end of the external metatarsus, outside 

 the branch furnished by the long lateral peroneus to that bone. 



The superior fasciculus acts as a proper extensor of the external digit. The inferior is an 

 abductor of the foot. 



2. Posterior Tibial Region. 



A. Ruminants.— In the Ox, Sheep, and Goat, tlie muscular portion of the perforatum 

 is thicker than in Snlipeds. The portion of the per/oratis which represents the tibialis posticus 

 is also better defined than in them ; it is lodged in a depression on the principal portion, and 

 can easily be traced from the supero-external surface of the tibia, where it originates. The 

 tendon does not differ from that in the fore limb; but the bands which descend from the 

 metatarsus to the heels, to be united witli the two terminal branches of this tendon, are much 

 smaller than those in tiie metacarpal region. 



In the Camel, the popliteus is altogether confined to the upper and posterior part of the 

 tibia. The perforatus is almost exclusively tendinous ; in its deeper portion there is a slight 

 expansion in which there are a few muscular fibres. The perforans has a very small fusiform 

 muscle ; its tendon glides on the internal face of the oscalcis, in a slight depres.sion representing 

 the tarsal bursa; it unites with the oblique flexor, and comports itself as in the anterior limb. 

 The oblique flexor of the phalanges is remarkable for its volume; instead of being an accessory 

 to the deep flexor, as in the other species, it alone forms the principal head of the perforans 

 tendon, the essential fleshy body of which is found, on the contrary, to be represented in the 

 majority of the other animals, by the analogue of the long flexor of the great toe. 



B. Carnivora.— The soleus is absent in the Dog, but it is found in the Cat. The 

 muscular body of the perforatus is prismatic, voluminous, and entirely blended— in its upper 

 two-thirds at least— with the external head of the gastrocnemius; these two muscles have 

 therefore a common origin. The tendon is quadrifurcated, as in the anterior Umb ; it offers 

 on its surface, shortly before its division, several thin muscular bands, traces of the fleshy 

 portion of the common short muscle of the toes in Man. Several of these bauds come from 

 the perforans tendon, and all pass to the four terminal branches of the muscle. The terminal 

 tendon of the perforans is divided into four or five branches, one for each digit. 



The posterior tibial is not united, inferiorly, to this tendon, but constitutes a perfectly 

 distinct muscle situated between the deep and oblique flexors of the phalanges. Formed by a 

 very small fleshy body and a long thin tendon, it arises above the peroneus, from the posterior 

 surface of the tibia. Its tendon lies beside that of the oblique flexor, and with it enters the 

 groove behind, and within the inferior extremity of, tlie tibia. Enveloped by a synovial mem- 

 brane proper to its passage through this groove, this tendon soon leaves it to pass to the free 

 surface of the posterior tarso-metatarsal ligament, with which it is blended towards the middle 

 of the tarsus. 



Comparison of the Muscles of the Leg of Man with those of Animals. 



In Man, the muscles of the leg are divided into three regions : an anterior, external, and 

 posterior. 



1. Anterior Region (Fig. 20t5). 

 This includes three muscles : 



1. The anterior tibial, which corresponds to the fleshy portion of the flexor of the meta- 

 tarsus, and the imperforate tendon of which is fixed into the first cuneiform. 



2. The common long extensor of the toes, which represents the anterior extensor of the 

 phalanges of the Horse. This muscle is attached, above, to the external tuberosity of the 

 tibia and the upper three-fourths of the inner face of tlie fibula : its tendon divides into two 

 fasciculi, the internal of which furnishes a branch to the second, third, and fourth toes, and 

 tiie external goes to the fifth. 



3. The proper extensor of the great toe, represented in the Dog by a small fasciculus 

 blended with the anterior tibial, is an elongated semi-penniform muscle that arises from the 

 inner face of the fibula and the interosseous ligament, and terminates on the second phalanx of 

 the great toe, after receiving the pedal tendon (extensor brevis digitorum). 



