408 ABDOMEN 



on the right side join the vena azygos, and the corresponding 

 veins on the left side, end in the hemiazygos vein ; the others 

 pour their blood into the inferior vena cava. The lower veins 

 of the left side pass behind the aorta. The lumbar veins of 

 each side are linked together, in front of the transverse 

 processes of the vertebrae, by anastomosing channels which 

 form a continuous longitudinal vessel, called the ascending 

 lumbar vein. The upper end of the ascending lumbar vein 

 is connected with the corresponding azygos vein. 



Subcostal Artery. At this stage of the dissection the 

 subcostal artery, the last parietal branch of the thoracic 

 aorta, will be seen crossing the upper part of the quadratus 

 lumborum, in company with the last thoracic nerve. It lies 

 in series with the abdominal branches of the lumbar arteries 

 and it accompanies the last thoracic nerve. 



Dissection. The lower limbs having, by this time, been 

 removed from the trunk, the pelvis also may be detached. Place 

 a ligature around the aorta and inferior vena cava at the level 

 of the bifurcation of the former, and divide them immediately 

 above that point. Then carry the knife through the interverte- 

 bral fibro- cartilage which intervenes between the third and 

 fourth lumbar vertebrae, and, having cut the nerves and soft parts, 

 complete the separation of the pelvis from the remainder of the 

 trunk by means of a saw. 



PELVIS. 



The pelvis, using the term in its widest sense, is the region 

 bounded posteriorly by the sacrum and coccyx, and laterally 

 and anteriorly by the hip bones. The bony wall is deficient, 

 on each side posteriorly, between the sacrum and coccyx 

 behind and the hip bone in front. The interval on each 

 side is partially filled in by the ligamentum sacro-tuberosum 

 (O.T. great sacro-sciatic ligament} and the ligamentum sacro- 

 spinosum (O.T. small sacro-sciatic ligament}, which divide it 

 into the greater and lesser sciatic foramina. Anteriorly, on 

 each side, the bony wall is broken by the obturator foramen, 

 which is closed by the obturator membrane ; and directly in 

 front there is a gap bounded by the pubic arch and occupied 

 by the urogenital diaphragm and its fasciae (O.T. triangular 

 ligament}. 



