2IO THE SURGICAL ANATOMY OF THE HORSE 



aspect of the limb in front of the tendo-Achilles, where is is regarded as 

 the posterior root of the internal saphena vein. It takes a course up 

 the leg which is obliquely upwards and forwards, crossing the posterior 

 tibial artery and the popliteus muscle, and joins the anterior root of 

 the internal saphena vein in the manner already described. 



The Deep Metatarsal Vein. — This runs up the metatarsal region on 

 the back of the large metatarsal bone, and between it and the suspensory 

 ligament. Near the hock it is joined by a branch from the external 

 metatarsal vein, and then passes forwards through the cuboido-scaphoido- 

 cunean canal alongside the perforating metatarsal artery, and on leaving 

 the canal it becomes the principal root of the anterior tibial vein. 



The Anterior Tibial Vein. — This is a large vein which is frequently 

 double, and it commences at the front of the tarsus by the union of a 

 number of vessels, the chief of which is that which comes forward 

 through the canal referred to above. The vein follows the course 

 taken by the corresponding artery, and is therefore deeply seated. 

 Running up the front of the tibia, it passes backwards through the 

 tibio-fibular arch and joins the posterior tibial vein to form the popliteal 

 vein. 



The Posterior Tibial Vein. — This vein commences near the hock in 

 front of the tuber calcis, its roots communicating with the saphena 

 veins. It follows the course of the posterior tibial artery, and terminates 

 by assisting to form the popliteal vein by uniting with the anterior tibial 

 vein as already stated, the union taking place on the deep face of the 

 popliteus muscle. 



The Internal Saphena Vein. — This vein has two roots which are the 

 upward continuations of the internal and external metatarsal veins, and 

 which unite in the manner already described. The enormous vein thus 

 formed continues its upward course on the surface of the sartorius muscle, 

 and usually passes into the interstice between this muscle and the gracilis 

 to join the femoral vein. Occasionally, however, it may be found to 

 join the pudic vein. 



