162 MUSCULAR SYSTEM. 



bone, and to the posterior side of the fibula. Inferiorly, the ten- 

 don assumes the name of tendo peij'orans, and is disposed of in 

 a manner so similar to the tendon of the same name in the fote 

 extremity as to render any description of its lower attachments 

 here quite unnecessary. 



Relations. — Posteriorly, with the plantaris and the gastrocne- 

 mii, and also with the posterior tibial bloodvessels; anteriorly, 

 with the tibia and fibula. Superiorly and internally, with the 

 flexor accessorius ; externally, with the plantaris and the flexor 

 metatarsi. 



Structure. — Superior attachment, both tendinous and fleshy, 

 from which at the back of the hock proceeds a strong cordiform 

 tendon, which passes within a groove upon the inner side of the 

 OS calcis and runs down the posterior part of the leg, where it 

 becomes connected with the tendons of the flexor accessorius and 

 gastrocnemius interims. With the former of these it unites, and 

 the two together form a single tendon ; but with the latter, the 

 union is only one formed by cellular membrane. The tendon is 

 denominated the tendo petforans, in contra-distinction to that 

 derived from the gastrocnemius internus, which (as was before 

 observed) is styled the tendo perforatus. Both tendons are 

 inclosed within the same sheath ; and are, in fact, disposed of 

 down the leg and foot in a similar manner to what the cor- 

 responding tendons are in the fore extremity : on which account 

 any further detail would prove but recapitulatory. 



Action. — That of the gastrocnemius internus corresponds to 

 that of the externus : it extends the hock. But, as it continues 

 down the leg through the medium of the tendo perforatus, it 

 will also flex the fetlock and pastern joints. The flexor pedis 

 will prove of some effect in the extension of the hock : although 

 its principal operation is u])on the foot, which it alone flexes ; and 

 at the same time it flexes the pastern and the fetlock. 



FLEXOR PEDIS ACCESSORIUS. — Peroieo-phdlangeus. 



Situation. — Deep seated : postero-internal part of the leg. 



Figure. — Elongated; fleshy portion pyramidal. 



Attachment. — Su\)ev\oY\y, to the postero-external part of the 

 head of the tibia : inferiorly, it becomes inseparably united with 

 the tendon of the flexor pedis, about one-third of the length of 

 the cannon downwards. 



Relations. — Posteriorly, with the gastrocnemii ; anteriorly, 

 with the body of the tibia, and the posterior tibial artery and 

 vein. Superiorly and internally, with the popliteus ; inferiorly 

 and externally, with the flexor pedis. 



Structure. — Superior attachment, fleshy and tendinous ; after- 

 wards entirely fleshy, and so it continues until it ends in a tendon 



