696 BLOOD-VASCULAR SYSTEM OF THE HORSE 



otherw'ise to the artery. The external pudic vein (V. pudenda externa) arises 

 chiefly from a rich plexus of large veins situated above and along the sides of the 

 penis and prepuce in the male, the mammary glands in the female. It passes 

 through a foramen in the anterior part of the tendon of origin of the gracilis and 

 runs outward behind the pectineus to unite with the deep femoral vein. The right 

 and left veins are connected by a large transverse anastomotic branch which lies 

 in the subpubic groove, and each has a large connection with the obturator vein. 

 Each receives the posterior abdominal vein (V. abdominalis caudalis), which ac- 

 companies the artery of like name. The subcutaneous abdominal vein (V. ab- 

 dominalis subcutanea) arises in the skin and cutaneous muscle of the ventral 

 abdominal wall, anastomoses with the internal and external thoracic and deep 

 abdominal veins, and joins the external pudic or the posterior abdominal vein. 

 A small vein accompanies the external pudic artery in the inguinal canal. 



2. The anterior femoral vein (V. femoris cranialis) accompanies the artery. 



3. The saphenous vein (V. saphena) (Figs. 575, 576, 583) arises on the dorso- 

 medial surface of the tarsus as the upward continuation of the medial metatarsal 

 vein. Its course is distinctly visible. It ascends on the subcutaneous surface of 

 the tibia and the popliteus muscle, enclosed between layers of the deep fascia, in- 

 clines a little backward to the proximal part of the leg, then deviates slightly for- 

 ward, runs upward on the gracilis, passes between that muscle and the sartorius, 

 and joins the femoral or the external pudic vein.i On the upper part of the capsule 

 of the hock joint it forms an arch with the anterior tibial vein. The vein has 

 numerous valves. The satellite artery is relatively small, and lies in front of the 

 vein as far as the junction with the recurrent tibial vein, which it accompanies on 

 the leg. It receives the recurrent tibial vein (V. recurrens tibialis) at the proximal 

 fourth of the leg. This vessel arises at the distal third of the leg, where it forms an 

 arch with the posterior tibial vein; here it is a satellite of the artery of like name. 

 It ascends in the furrow in front of the gastrocnemius tendon, inclines forward at 

 the proximal third of the leg, and joins the saphenous vein at an acute angle. It 

 gives off a branch which ascends with the artery and joins the posterior femoral or 

 the popliteal vein.^ A smaller vein from the anterior face of the metatarsus joins 

 the saphenous at the hock. 



4. Muscular branches which correspond to the arteries. 



5. The posterior femoral vein (V. femoris caudalis) is a satellite of the artery. 

 It receives the recurrent tarsal vein (V. tarsea recurrens), which arises at the lateral 

 side of the hock, ascends on the deep fascia of the lateral surface of the leg in front 

 of the tendo Achillis, passes between the biceps femoris and semitendinosus, and 

 joins the posterior femoral vein. It is connected with the recurrent tibial vein by 

 a large anastomotic branch which crosses in front of the tuber calcis. Usually a 

 branch from it ascends along the great sciatic nerve and anastomoses with the ob- 

 turator vein. 



The popUteal vein (V. poplitea) lies along the medial side of the artery (Fig. 

 584). It is formed by the confluence of anterior and posterior tibial veins. 



Two anterior tibial veins (Vv. tibiales anteriores) usually accompany the artery 

 of like name; the lateral vein is much the larger.^ In other cases there is a single 



' The place and mode of termination are quite variable. It may disappear from the surface 

 of the thigh at any point above the distal third. In some cases it passes through the anterior 

 part of the gracilis instead of dipping in between that muscle and the sartorius, and more rarely 

 it joins the external pudic vein at the origin of the gracihs. 



2 The arrangement here is subject to variation. Some authors regard the ascending branch 

 of this description as the trunk, and the connection with the saphenous as an anastomotic branch. 

 The latter is usually, so far as size is concerned, the trunk. 



^ The large size of this vein, the thinness of its wall, and the fact that it is separated only by a 

 thin layer of muscle (lateral part of tibialis anterior) from the deep peroneal nerve should be noted 

 with reference to section of that nerve. The vein is sometimes markedly varicose in the proximal 

 part of the leg. 



