644 THE VELXS 



even above the artery. (2) It luaj' pass with the artery behiud the scalenus anticus. (3) It may 

 ruu behind the scalenus anticus and the arterj' in front of that muscle. (4) It may split and 

 enclose the scalenus anticus. (5) It may pass between the clavicle and the sulx'lavius. (6) It 

 may receive directly the transverse cervical, the suprascapular, the anterior jugular, or the 

 cephalic vein, or the veua3 comites of the brachial artery. 



6. TIIF VEINS OF THE LOWER EXTREMITY 



The veins of the lower extremity are divided into the superficial and the 

 deep. The superficial veins lie in the subcutaneous tissue superficial to the deep 

 fascia, through which they receive numerous communicating branches from the 

 deep veins. They are collected chiefly into two main trunks, which, beginning 

 on the foot, extend upwards, one lying antero-internally, and the other |)ostero- 

 externally. The former finally joins the femoral vein by passing through the deep 

 fascia at the groin; the latter the popliteal by perforating the fascia at the ham. 

 The deep veins, on the other hand, accompany their corresponding arteries. 

 Below the knee there are two veins to each artery; above it, excepting at the back 

 of the thigh, there is only one vein to each artery. All the veins of the lower limb 

 have valves which are more numerous than in the veins of the upper extremity, 

 and in the deep than in the superficial veins. 



I. THE SUPERFICIAL VEINS OF THE LOWER EXTREMITY 



The superficial veins of the lower limb are collected into two main trunks. 

 One, the long or internal saphenous, which is placed antero-internally; the other, 

 the short or external saphenous, which is placed postero-externally. These veins 

 commence on the dorsum of the foot in an irregular arch, which stretches across 

 the instep Avith its convexity towards the toes. The arch receives branches from 

 the four outer toes and dorsum of the foot, and one branch of somewhat larger size 

 than the rest from the inner side of the great toe. It also communicates with the 

 venae comites accompanying the dorsal artery of the foot (fig. 397). 



The long or internal saphenous vein commences on the inner side of the foot 

 at the inner end of the above described venous arch, and, after receiving branches 

 from the sole which join it by turning over the inner border of the foot, passes 

 upwards in front of the inner ankle, and then obliquely upwards and backwards 

 about a finger's breadth from the posterior border of the tibia in company with the 

 internal saphenous nerve, which becomes sujierficial just beloAv the knee. Con- 

 tinuing its course upwards, it passes behind the internal condyle, and then runs 

 upwards and somewhat outwards on the inner side of the front of the thigh to 

 about an inch and a half beloAv Poupart's ligament, Avhere, after receiving the superfi- 

 cial circumflex iliac, superficial epigastric, and superficial external ])udic veins, it dips 

 through the saphenous opening in the fascia lata, and ends in the femoral vein. In 

 its course up the leg and thigh it receives numerous unnamed cutaneous branches, 

 and at varial^le intervals communicates Avith the deep veins. Just before it ])asses 

 through the saphenous opening, it often receives a large vein (external femoral 

 cutaneous) formed by the union of scA'eral of the cutaneous veins on the uj)per 

 and outer part of the thigh, and a second vein (the internal femoral cutaneous) 

 formed by the union of the cutaneous veins from the inner and back part of the 

 thigh. The long saphenous vein contains from ten to tAventy valves. 



The short or external saphenous vein begins at the outer end of the venous 

 arch, or plexus, on the dorsum of the foot. After receiving branches from the sole, 

 Avhich turn over the outer border of the foot, it passes behind the outer ankle, and 

 then upAA-ards and iuAvards, lying at first along the outer side of tlie tendo Achillis, 



