638 THE VEINS 



of that vessel, it leaves the artery and runs upwards on the psoas to the left of the 

 aorta and behind the })eritoneuni. On ap})roaching the })anereas it turns slightly 

 inwards, and passes obliquely behind that gland to join the splenic vein just before 

 tlie latter unites with the superior mesenteric to form the vena i)orta. 



THE VEINS OF THE PELVIS 



The veins of the pelvis, with the exception of the middle sacral vein, which 

 terminates in the left cunimon iliac vein, open into the internal iliac vein. Under 

 the head of i)elvic veins are included all of those corresponding to the branches of 

 the internal iliac artery except the hypogastric branch, although some of these veins 

 do not retin-n the lilood from the pelvic walls or viscera. 



The internal iliac vein is formed by the confluence of the veins (except the 

 uml)ilical) corresponding to the branches of the internal iliac artery. It varies 

 considerably in length, but is usually quite a short trunk, extending from the upper 

 part of the great sacro-sciatic foramen to the sacro-iliac synchondrosis, Avhere it 

 joins the external iliac to form the common iliac vein. It lies behind and a little 

 internal to the internal iliac artery. It contains no valve. 



Tributaries. — The internal iliac vein receives directly or indirectly the following 

 brandies: the gluteal, ilio-lumbar, lateral sacral, obturator, sciatic, pudic, dorsal 

 penile. }trustatic, vesical, and ha?morrhoidal veins. The single umbilical vein — the 

 vein corresponding to the right and left hypogastric arteries and their continuation, 

 the umbilical arteries — does not enter the pelvis, but, leaving the umbilical arteries 

 at the navel, passes along the falciform ligament to the liver. After birth it is 

 converted into a fibrous cord. (See Portal Vein, page 634. ) 



The gluteal veins accompany the gluteal artery, and, passing through the 

 upper part of the great sciatic foramen, open into the internal iliac vein near its 

 termination, either separately or as a single trunk. 



The ilio-lumbar veins open into the internal iliac a little higher than the 

 gluteal. At times they join the common iliac vein. 



The lateral sacral veins join the gluteal or the internal iliac at or about the 

 same situation as the gluteal. They form with the middle sacral veins a plexus in 

 front (»f the sacrum, and receive l:»ranches from the sacral canal. 



The obturator vein, which lies below the obturator artery as it crosses the side 

 of the pelvis, opens into the front of the internal iliac vein a little beloAV the gluteal. 

 Its branches correspond to those of the artery. 



The sciatic veins accompany the sciatic artery, and, as a rule, unite to form a 

 single trunk liefore joining the internal iliac a little below tlie ol)turator vein. 



All the al)ove veins so closely follow the ramifications of their respective 

 arteries, that no further special descri})tion of them is required. They all contain 

 valves. 



The pudic vein doi's not begin as the dorsal vein of the penis, but issues from 

 the corjius cavernosum with the artery of that body. It communicates, however, 

 with tlie dorsal vein before the latter pierces the triangular ligament. In the rest 

 of its course it runs with the pudic artery, receiving tributaries corresi)onding 

 to the branches of that vessel. It terminates in the lower part of the internal 

 iliac vein. 



The dorsal vein of the penis begins in a ])lexus around the corona glandis, 

 then runs along the centre of the dorsum of the penis between the two ]»udic 

 arteries. In this course it receives large trilmtaries from the interior of the organ, 

 which, emerging for the most part between the cori)US spongiosum and cor]nis 

 cavernosinn. wind obliquely over the outer surface of the latter structure to the 

 dorsiun of the penis to end in the dorsal vein. At the root of the penis the dorsal 

 vein leaves the dorsal arteries, and, passing straight backwards between the two layers 

 of the suspensory ligament, and then through either the sub])ubic ligament or the 

 upper part of the triangular ligament of the pelvis (fig. 371) bifurcates, each 

 branch passing backwards and downwards to the prostatico-vesical jilexus of veins. 

 At times the dorsal vein begins as two branches, which nm l)etween the dorsal 

 arteries and onlv unite to form a simple tnnik aliout an inch and a half from the 



