9IO HUMAN ANATOMY. 



internal abdominal ring, from the spermatic cord or round ligament of the uterus. 

 The connections which it makes with other veins are numerous and important. 

 Its connections with the superior epigastric vein have already been noted ; by this 

 communication is established between the superior and inferior venae cavae. In 

 addition, by means of branches which traverse the sheath of the rectus muscle, 

 it communicates with the subcutaneous and subperitoneal veins of the abdominal 

 wall and with the parumbilical veins, forming through these latter a connection 

 with the portal system of veins. Finally, by means of a pubic branch, which is 

 frequently a tributary of the external iliac rather than of the deep epigastric, it 

 communicates with the obturator vein, and by the enlargement of this communication 

 the obturator vein, just as is the case with the arter) , may become a tributary of the 

 deep epigastric. 



2. The Deep Circumflex Iliac Vein, — The deep circumflex iliac vein (v. 

 circumtlexa ilium profundaj has the same course as the corresponding artery, which 

 it surrounds in a plexiform manner. It possesses valves and communicates with the 

 iliolumbar veins. Near its termination it becomes a single trunk and opens into the 

 external iliac a little above the deep epigastric ; occasionally it opens into the latter 

 vessel. 



THE VEINS OF THE LOWER LIMB. 



The external iliac vein is the channel by which the blood returning from the 

 lower limb is conveyed to the inferior vena cava and is the direct upward continuation 

 of the femoral vein. Instead, however, of proceeding to a description of this latter 

 vessel and so down the leg, it will be more convenient to begin the account of the 

 veins of the lower limb with those of the foot and proceed upward to the femoral. 



As in the upper limb, two practically distinct sets of veins can be recognized in 

 the leg ; one set is more or less deeply seated and accompanies the arteries, while the 

 other is superficial and, in the adult, has a course quite independent of the arterial 

 distribution. The deep veins will first be considered. 



THE DEEP VEINS. 

 The Deep Veins of the Foot. 



The deep veins of the sole of the foot have their origin in a net-work with 

 more or less distinctly elongated meshes, which occurs upon the plantar surfaces 

 of the digits. These are the plantar digital veins (vv. digitales plantares), and 

 in the webs of the toes the vessels of each digit unite with those of the neighboring 

 ones to form a series of plantar interosseous veins (vv. metatarseae plantares) 

 occupying the metatarsal interspaces and forming venae comites for the plantar 

 interosseous (metacarpal) arteries. Just as the digital veins unite to form the 

 interosseous, they send dorsal branches (vv. intercapitulares), which unite with 

 the dorsal interosseous veins, and, in addition, make connections with the superficial 

 plantar veins, and might, indeed, be classed with these quite as appropriately as with 

 the deep set. ' 



The plantar interosseous veins pass backward, receiving branches from the 

 neighboring muscles, and open into a venous plantar arch (arcus venosus plantaris), 

 formed by the venae comites of the arterial plantar arch. These are continued pos- 

 teriorly into the external plantar veins, which pass obliquely across the foot along 

 with the corresponding artery and unite behind the inner malleolus with the internal 

 plantar veins to form the companion veins of the posterior tibial artery. Both 

 plantar veins give oG branches which perforate the plantar aponeurosis and communi- 

 cate with the superficial plantar veins, and connecting vessels also pass across the 

 sole of the foot between the two veins. 



Upon the dorsum of the foot there exist the dorsal digital veins (vv. digitales 

 dorsales), which, like the corresponding plantar veins, may be equally classified with 

 superficial or deep veins, since they make connections with both sets. In the webs of 

 the toes the vessels of adjoining digits unite to form the four dorsal interosseous 

 veins (vv. metatarseae dorsales), which occupy the metatarsal interspaces and com- 

 municate with the corresponding plantar veins by the intercapitular and perforating 



