914 HUMAN ANATOMY. 



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trunk and is the direct continuation of the popliteal vein below, and it terminates by 

 becoming continuous with the external iliac \ein above. In its lower part it lies 

 slightly external to the artery, but throughout the greater part of its course it rests 

 upon the posterior surface of the artery and is enclosed in a common sheath with k. 

 Above it inclines somewhat inwardly and comes to lie upon the inner surface of the 

 artery, between it and the femoral canal. It possesses from one to five pairs of 

 valves, the most constant pair, present in Si per cent, of cases, being situated in the 

 upper 5 cm. of the \'ein and consequently controlling the flow from all the veins of 

 the lower limb. 



Tributaries. — The tributaries of the femoral vein correspond with the branches 

 ot the femoral artery, although some of them communicate with the vein only indirectly, 

 opening primarily into the long saphenous vein, which is itself a tributary of the 

 femoral. Thus, the long saphenous usually receives the external pvidic, superficial 

 circumflex iliac, and superficial epigastric veins, and these will be described later 

 with the saphenous veins. Of the remaining tributaries, (i) the deep /em ora/, (2) 

 the ve?iiz comixes, and (3) the anastomotica magna, the first two deserve special 

 mention. 



1. The Deep Femoral Vein. — The deep femoral vein (v. profunda femoris) 

 accompanies the deep femoral artery, and, like it, receives as tributaries perforating 

 veins (vv. perforantes) which take their origin upon the posterior surface of the 

 adductor muscles and anastomose with one another, with tributaries of the popliteal 

 below and witn the sciatic above. The lowest perforating" vein, which represents the 

 actual beginning of the deep femoral, has communicating with it one of the terminal 

 branches of the short saphenous vein. The deep femoral vein also receives the 

 internal and external circumflex veins (vv. circumflexa femoris medialis et 

 lateralis) which accompany the corresponding arteries as their venae comites, the 

 internal circumflex anastomosing with the sciatic and obturator \eins and so 

 providing for a possible collateral circulation between the internal and external iliac 

 veins. The deep femoral opens into the femoral usually about 4-5 cm. below 

 Poupart's ligament, but not infrequently at a somewhat higher level, and the 

 circumflex veins may open directly into the femoral instead of into the deeper vein. 



2. The Venae Comites. — The venae comites of the femoral artery are two or 

 three small stems which run parallel with the artery and \'ein through Hunter's 

 canal. One lies to the inner side of the artery (v. comitans medialis) and the other 

 to the outer side (v. comitans lateralis), and when a third is present it accompanies 

 the long saphenous nerve. They communicate with, or in some cases receive, the 

 veins issuing from the adjacent muscles and open into the femoral vein, usually a 

 little below the point where it receives the deep femoral vein. 



Variations. — The portion of the femoral \'ein above the entrance of the deep femoral is 

 sometimes termed the common femoral vein and the rest of it the superficial femoral, the 

 common femoral being formed by the union of the superficial and deep veins. 



Occasionally the vein lies anterior to the artery throughout a considerable portion of its 

 course, and it may be double to a greater or less extent, the two veins in such cases either lying 

 posterior to the artery or one on either side of it. 



It occasionally passes up the leg behind the adductor magnus, passing through the muscle 

 where it is normally perforated by one of the perforating veins, this arrangement being 

 apparently due to the enlargement of a connection with the deep femoral and of the anastomosis 

 between the perforating veins, hi such cases the femoral artery is accompanied by one or two 

 small stems, perhaps representing the venie comites, and in those cases in which the popliteal 

 vein passes up the back of the thigh ( page 911) the femoral is also greatly reduced in size. 



THE SUPERFICIAL VEINS. 



The Superficial Veins of the Foot. 



It has already been pointed out (page 910) that the dorsal and plantar digital 

 veins mav be grouped either with the superficial or deep veins of the foot, since they 

 communicate extensively with both sets. The superficial connections of the plantar 

 digitals are with an arcus vcnosus plantaris cutancus which runs across the foot at the 

 bases of the toes and, bending upward over the edges of the foot, communicates with 

 the dorsal veins. Posteriorly to this arch is a subcutaneous net- work (rcte venosiim 



