454 



Veins of the Trunk. 



Plexus venosi vertebralis interni/i 



Corpus 

 vertebrae 



-Processus articularis superior 



Anastomosis with the plexus 

 ,-vcnosus vertebralis posterior 



Fibrocartilago 

 intervertebralis" 



"-^Plexus venosus verte- 

 bralis posterior 

 Foraiueu intervertebrale 



Sinus vertebralis 

 longitudinalis 



' Processus spinosus 



493. Spinal VGinS, seen in a median section, viewed from the left. 



y. SUl)Cljlvia (subclavian vein) (see Fig. 486) is the name of the continuation of the 

 V. axillaris from the lower margin of the m. subclavius on. It accompanies the a. subclavia on 

 its anterior and inferior surface and crosses the first rib in front of them, scalenus anterior. 

 Behind the articulatio sternoclavicularis it helps to form the v. anonyma. It has valves at its 

 beginning and at its termination. In addition to it some small veins directly accompany the 

 a. subclavia. Tributaries (besides the v. jugularis externa): 



1. and 2. V. transversa scapulae and y. transversa colli (see Figs. 486 and 489) 

 near the corresponding arteries, unite usually to form one stem, which fi-equently opens into 

 the V. jugularis externa. They carry valves at their mouths. 



Veins of the spinal column, in the canalis vertebralis, between the two layers 

 of the dura mater spinalis, lie close venous plexuses, plexus venosi vertebrates interni, the 

 tributaries of which come partly from th(> verteljrae, partly from the spinal cord. These j)lexuses 

 (see also i'ig. 494) extend chiehy in the longitudinal direction from tJie foramen occipitale magnum 

 to almost as far as the tip of the sacrum and permit the recognition of four trunks, two anterior 

 and two posterior. The anterioi- lie upon the posterior surface of the bodies of the vertebrae 

 and of the intervertebral disks on each side lateral from tbe lig. longitudinale posterius; they 

 consist of several large veins, running very close together, which anastomose manifoldly with 

 one another, possess a lumen which stands open especially in the cervical and thoracic part 

 and are accordingly also called the sinus vertebrates tongitudinales. Tbe posterior plexuses 

 are situated on both sides on the anterior surface of the arcus vertebrarum and of the ligamenta 

 flava and anastomose through spaces in the latter with the plexus externi posteriores ; they are 

 more delicate and less numerous and form more irregular, wider networks. The anterior plexuses 

 are imited with one another on the posterior surface of each vertebral bodj' by transverse trunks, 

 whicb run between the periosteum and the lig. longitudinale posterius and there receive the 

 vv. basivertebrales. The latter (see also Fig. 494) extend radially in the vertebral body toward 

 the middle of the postei'ior surface and open there in common or separately, being provided at the 

 mouth with valves; in front they anastomose through tbe bones with the plexus externi anteriores. 

 The posterior plexuses are connected with one another by branches arranged in the form of a 

 network; with the anterior they are connected by numerous shorter vessels which are present 

 especially on the medial side of each radix arcus vertebrae and leave free only the upper part 

 of the I'oramen intervertebrale. Through the connecting branches of the different plexuses with 

 one another arise the more or less distinct vascular rings, retia venosa vertebrarum, one at 

 the level of each vertebra. The upper end of the plexus surrounds the foramen occipitale magnum 

 like a wreath (see Fig. 484), is connected with the sinus occipitalis, plexus basilaris and rete 

 canalis hypoglossi and empties into the v. vertebralis. In the canalis sacralis the vessels become 

 smaller, the plexuses become looser and empty through the foramina saci'alia into the vv. sacrales. 



