472 



VEINS OF THE TRUNK. 



and intercostal arteries, and open into the veins which acompany those 

 vessels. 



6. The veins belonging to the bodies of the vcrtebrce (vense basis verte- 

 brarum, Dupuytren) are comparatively large vessels contained in the 

 canals within the bodies of the vertebrae ; the arteries which accompany 

 them being very small. They anastomose on the front of the bones with 

 some of the superficial veins ; and the trunk of each, having reached the 

 spinal canal through the foramen in the posterior surface of the body of the 

 vertebra, divides into two branches, which diverge and terminate in the 

 large spinal veins behind the bodies of the vertebrae. 



c. The anterior longitudinal spinal veins. The blood collected by the 

 different vessels here described is poured into two large veins, or rather 

 tortuous venous canals, which extend, one on each side, along the whole 

 length of the spinal canal behind the bodies of the vertebrae. These 

 vessels (the great spinal veins of Breschet) are alternately constricted and 

 enlarged, the constricted points corresponding with the intervertebral 

 foramina, where they are drawn forwards, and bound down by the branches 

 of communication which pass outwards. In some parts the veins are double, 

 or even triple, so as to form a plexus, and occasionally they are altogether 

 interrupted. In the thoracic region their communicating branches open 

 into the intercostal veins, in the loins into the lumbar veins, in the neck 

 for the most part into the vertebral. 



Fig. 32]. Fig. 321, A and B. HORIZONTAL AND VERTICAL 



SECTIONS OP THE LOWER DORSAL VERTEBRAE, 

 SHOWING THE EXTERNAL AND INTERNAL VEINS 

 OF THE SPINE (after Breschet). f 



a, spinons process; b, transverse process; c, 

 body; d, spinal canal; 1, anterior external veins 

 of the body; 2, posterior external veins of the 

 vertebral column communicating with the internal 

 and forming a plexus over the laminae and pro- 

 cesses ; 3, the posterior, and 4, the anterior in- 

 ternal plexus of veins of the vertebral canal ; 5, 

 the internal veins of the body joining the internal 

 spinal veins ; 6, the lateral veins, which are joined 

 by the internal and external spinal veins, and 

 themselves unite with the intercostal. 



d, The posterior longitudinal spinal veins 

 are a complex interlacement of tortuous 

 veins along the inner or anterior surface 

 of the arches of the vertebrae. In the 

 lower part of the canal this interlacement 

 of veins is not so close as in the upper 

 portion, where it usually conceals (if the 

 injection has been successful) the whole 

 surface of the dura mater. These veins 

 converge to the intervertebral foramina, 

 and join by rather small vessels with the 

 intercostal veins. 



e - The veins of the spinal cord (Breschet) ramify upon the cord and its 

 nerves, enclosed within the sheath formed by the dura mater. Though 

 they communicate with the other spinal veins, they are not injected with 

 them, even when the injecting process is most successful. Yery small, 



