CIRCULATORY SYSTEM. 219 



The Femoral Vein 



Fs the continuation of the external iliac trunk below the brim of 

 the pelvis, and becomes the main channel into which the deep- 

 seated veins of the hind extremity pour their blood. It will be 

 more regular to commence the description of the veins of the 

 hind extremity from below, having already proceeded so with those 

 of the fore extremity ; but it will not be necessary to descend so 

 low down as the foot, the plantar veins being similar both behind 

 and before : we may begin therefore at the leg. 



The large metatarsal vein having ascended about half- 

 way up the cannon, by the side of the flexor tendons, leaves them 

 and takes an oblique cours^e over the bone to reach the anterior 

 and inner part of the hock, where it sends down an anastomotic 

 branch under the tendon of the flexor metatarsi, from which anas- 

 tomosis with the small metatarsal vein, and from the accession 

 of a branch coming from the hock, results the 



Anterior tibial vein or veins ; for there are commonly two 

 veins accompanying the anterior tibial artery. They ascend be- 

 tween the tibia and fibula as high as the inferior and posterior 

 part of the os femoris, and there are joined by the posterior tibial 

 vein ; all three uniting to form the femoral. 



The posterior tibial vein is a continuation of the small 

 metatarsal vein, which latter corresponds in comparative size and 

 course to the small metacarpal vein. This vessel runs in com- 

 pany with the posterior tibial artery, receiving various muscular 

 branches in its course, and also the medullary vein of the tibia. 



The femoral vein is one of large size. It begins at the 

 place of union of the two last-described vessels, runs behind the 

 femoral artery, and ends in the external iliac vein. It receives 

 various large muscular veins, corresponding to the principal 

 branches of the arterial trunk, as well as veins from the stifle-joint, 

 and also the medullary vein of the os feinoris. Likewise, about 

 two-thirds of its length upward, it is joined by the saphena vein. 



The vena saphena major, the principal superficial vein of 

 the hind extremity, takes its rise, at the inner and fore part of the 

 hock, from the large metatarsal vein ; at which place a branch 

 from the major ascends obliquely round the inner side of the joint 

 to join the vena saphena minor. It then makes an oblique ascent 

 up the middle of the thigh, across the surface of the gracilis 

 covered only by the skin, and high up plunges inward among the 

 muscles to join the femoral trunk. At the hock, it has a remark- 

 able anastomosis with the anterior tibial vein, thus establishing 

 a communication between the deep-seated and superficial veins; 

 it also receives many cutaneous and muscular branches in its- 



