MUSCLES OF THE POSTEHIOB LIMBS. 309 



B. Posterior Tibial Begion. 



EtJMTNANTS.— In the Ox, Sheep, and Goat, the muscular portion of the perforatus is 

 thicker than in Solipeda. The portion of the perforam is better defined than In Solipeda, 

 and is lodged in a depression on the principal portion ; it 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 with the two terminal branches of this tendon, are much smaller tiau those in 

 the metaoai-pal region. 



Caknivoka. — The soleus is absent in the Bog and Cat. The muscular body of the 

 perforatus is prismatic, voluminous, and entirely'blended, in its upper two-thirds at least, 

 with the external gastrocnemius ; these two muscles have therefore a common origin. The 

 tendon is quadrifurcated, as in the anterior limb ; it offers on its surface, shortly before 

 its division, several thin muscular bands, traces of the fleshy portion of the common short 

 muscle of 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, this muscle originates 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 

 the tibia. Enveloped by a synovial membrane 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. 



COMPAKISON OP THE MUSCLES OF THE LES OP MAN WITH THOSE OP ANIMALS. 



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

 and posterior 



A. Anterior Begion, 



This includes three muscles : 



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

 metatarsus, and whose imperforate tendon is fixed into the first cuneiform. 



2. The common long extensor of the toes, which represents the anterior extensor o 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 the fibula ; its tendon divides into 

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

 toes, and the external goes to the fifth. 



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

 blended with the anterior tibial, is an elongated semi-penniform muscle which 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). 



B. External Begion. 



This region is only composed of two muscles : the long and short peroneus. 



The first, which does not exist in Solipeds, is a penniform muscle attached to the 

 upper third of the fibula, the external tuberosity of the tibia, and the internal face of the 

 tibial aponeurosis, by the superior extremities of its muscular fibres. The flat tendon 

 which terminates it is fixed to the outer portion of the base of the first metatarsal. 



The second corresponds to the lateral extensor of the phalanges of the Horse, and is 

 found in all animals. It is penniform, and is attached above, by its fieshy fibres, to the 

 lower two-thirds of the external face of the fibula; below, by its tendon, to the upper 

 extremity of the fifth metatarsal. 



These two muscles determine very complicated movements in the region of the foot. 



C. Posterior Begion. 



The posterior tibial muscles form two layers : a supei-ficiai and a deep 



The first comprises the crural triceps and the plantaris. The triceps itself is 



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