684 THE BLOOD-VASCULAR SYSTEM 



other, the small saphenous, postero-laterally. The former finally joins the 

 femoral vein by passing through the deep fascia at the groin; the latter, the pop- 

 liteal b}^ perforating the fascia at the ham. The deep veins, on the other hand, 

 accompany their corresponding arteries. 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 begin in the plexuses of the foot. The 

 dorsal digital veins [vv. digitales pedis dorsales] collect blood from the dorsal 

 surfaces of the toes and unite in pairs, around each cleft, to form the dorsal 

 metatarsal veins [vv. metatarsese dorsales pedis]. The dorsal metatarsal veins, of 

 which the first and fifth are larger than the others, join the dorsal venous arch 

 [arcus venosus dorsalis pedis]. This arch is convex toward the toes and crosses 

 near the bases of the metatarsal bones. From the medial and lateral ends of the 

 arch the great and small saphenous veins, respectively, take origin. The area 

 of the dorsum of the foot contained between the arch and the two saphenous 

 veins is covered by the dorsal venous rete [rete venosum dorsale pedis] which 

 extends as high as the ankle-joint (fig. 539). 



On the plantar surface the plantar digital veins [vv. digitales plantares] 

 return the venous blood to the clefts of the toes and unite to form the common 

 digital veins [vv. digitales communes pedis]. The common digital veins join 

 freely with one another on the sole to form the plantar venous rete [rete venosum 

 plantare]. There are numerous communications between the superficial veins 

 of the dorsum and sole. These occur both in the clefts of the toes, by means of 

 the intercapitular veins [vv. intercapitulares], and around the margins of the 

 foot. Communications between the superficial and deep veins of the foot are 

 very free (fig. 540). 



The great (or internal) saphenous vein [v. saphena magna] (fig. 538) com- 

 mences as the medial end of the dorsal venous arch, and, after receiving 

 branches from the sole which join it by turning over the medial border of the 

 foot, passes upward in front of the medial malleolus, and then obliquely up- 

 ward and backward about a finger's breadth from the posterior border of the 

 tibia in company with the saphenous nerve, which becomes superficial just be- 

 low the knee. Continuing its course upward, it passes behind the medial epi- 

 condyle, and then runs upward on the medial side of the front of the thigh to 

 about 3.7 cm. (1 j in.) below the inguinal ligament, where it dips through the fossa 

 ovalis (saphenous opening) in the fascia lata, and ends in the femoral vein. 



Tributaries. — la its course up the leg and thigh it receives numerous unnamed cutaneous 

 tributaries. As it passes up the thigh it often receives a large vein, the femoro-popliteal which 

 communicates with the small saphenous, and several of the cutaneous veins on the lateral part of 

 the thigh, and a second vein, the accessory saphenous [v. saphena accessoria], formed by the 

 union of the cutaneous veins from the medial and back part of the thigh (fig. 538). The great 

 saphenous vein contains from ten to twenty valves. 



Immediately before entering the fossa ovalis the great saphenous vein receives the super- 

 ficial epigastric, superficial circumflex iliac, and external pudendal veins, though any of these 

 veins — or all of them — may pierce the fascia separately and enter the femoral vein. 



The superficial epigastric vein [v. epigastrica superficialis] anastomoses with the superficial 

 abdominal, and parumbilical veins. 



The superficial circumflex iliac vein [v. circumflex ilium superficialis] anastomoses with the 

 thoraco-epigastric and the superficial circumflex iliac veins. 



The external pudendal veins [vv. pudenda; externa;] collect venous blood from the anterior 

 scrotal or labial veins, whicli anastomose with the posterior scrotal or labial veins, and from the 

 subcutaneous veins of the dorsum of the penis [vv. dorsales penis subcutanea;]. 



The small saphenous v(^in [v. saphena parva] (fig. 539) begins at the lateral end 

 of the venous arch on the dorsum of the foot. After receiving branches from the 

 sole, which turn over the lateral border of the foot, it passes l)ehind the lateral 

 malleolus, and then upward and, lying at first along the lateral side of the tendo 

 Achillis, afterward along the back of the calf, in company with the sural (short 

 saphenous) nerve, to about tiic lower part of the centre of the popliteal space, 

 where it perforates the deep fascia, and, sinking l)etween the two heads of the 

 gastrocnemius, opens into the popliteal vein. 



