THE VEINS OF THE LOWER LIMB. 911 



veins. They form the venae comites of the dorsal interosseous (metatarsal) arteries aiid 

 open into the companion veins of the metatarsal artery. These, together with the veins 

 accompanying the tarsal arteries, open into the venae comites of the art. dorsalis pedis, 

 and these in turn are continuous with the venae comites of the anterior tibial artery. 



The Deep Veins of the Leg. 



The deep veins of the leg are the venae comites of the posterior and anterior 

 tibial arteries and their branches. The posterior tibial vein (v. tibialis posterior) 

 is formed behind the internal malleolus by the union of the internal and external 

 plantar veins, and consists of two, or in many cases three, veins accompanying the 

 posterior tibial arterv. It terminates at the lower border of the pophteus muscle by 

 uniting with the anterior tibial veins to form the popliteal, and possesses in its course 

 from eight to twenty valves. A short distance below the popliteus muscle it receives 

 the peroneal veins (v\'- peroneae) which accompany the peroneal artery. They are 

 usually of larger calibre than the posterior tibial veins, receiving a larger share of the 

 vessels which come from the posterior crural muscles, and they anastomose with the 

 posterior tibials by frequent transverse branches, and also with the anterior tibials. 

 They possess from eight to ten valves. 



The anterior tibial veins (vv, tibiales anteriores) are the upward continuation 

 of the venae comites of the art. dorsalis pedis. They accompany the anterior tibial 

 artery, and are united across the artery by numerous transverse anastomoses. They 

 pass with the artery to the posterior surface of the crus above the interosseous mem- 

 brane and unite with the posterior tibials to form the popliteal vein. They make 

 communications with both the peroneal and posterior tibial veins by branches which 

 perforate the interosseous membrane, and are furnished, on the average, with about 

 eleven valves. 



The Popliteal Vein. 



The pophteal vein (v. poplitea) (Fig. 768) is a single trunk formed by the union 

 of the anterior and posterior tibial veins at the lower border of the popliteus muscle, 

 and it extends from that point to the opening in the adductor magniis which transmits 

 the femoral artery. It is throughout closely bound down by dense connective tissue 

 to the popliteal artery, and lies betw-een that vessel and the internal popliteal nerve. 

 Its course, however, is not quite parallel to that of the artery, but in its lower part 

 it is slightly internal to the artery and in its upper part somewhat external to it. 

 The popliteal vein possesses from one to four valves and is directly continuous above 

 with the femoral vein. 



In addition to the popliteal vein, the popliteal artery has two other smaller veins 

 accompanying it. The external one (v. comitans lateralis) has its origin from the 

 veins issuing from the outer head of the gastrocnemius and the soleus, and passes 

 upward along the outer surface of the artery to open into the popliteal vein at about 

 the middle of its course. The inner vena comitans (v- comitans medialis) is formed 

 by the veins issuing from the inner head of the gastrocnemius and ascends along the 

 inner side of the artery, making connections with the inferior and superior internal 

 articular veins, to open into the popliteal vein just below the opening in the adductor 

 magnus. 



Tributaries. — The majority of the tributaries of the popliteal vein correspond 

 to the branches of the popliteal artery, — that is to say, they are articular and 

 muscular. In addition it receives the short saphenous vein at about the middle of 

 its course. 



Variations. — The popliteal vein may be considerably shorter than usual owing to the fail- 

 ure of the tibial veins to unite at the customary level. Not infrequently the vein is double 

 throughout a portion of its course, more rarely throughout its entire length, and it occasionally 

 lies beneath [i.e., anterior to) the artery. 



It normally communicates by means of its tributaries with branches of the deep femoral 

 vein, and occasionally this communication becomes so large that the popliteal seems to bifurcate 

 above, one branch becoming continuous with the femoral and the other with the deep 

 femoral. More interesting from the historical stand-point are the rare cases in which the vein 



