DUCTS, VESSELS, AND NERVES, ETC. 181 



The spermatic veins accompany the spermatic arteries in 

 a part of their course ; they are formed by the union of 

 several venous branches which surround the spermatic 

 cord, and ascend as single trunks, the right to enter the 

 vena cava and the left to join the left renal vein. It has 

 been attempted to explain the more frequent occurrence of 

 varicocele upon the left side, by the less direct entrance of 

 the blood from the vein of that side into the general cir- 

 culation. 



The abdominal aorta will be found to terminate in two 

 branches at the level of the third lumbar vertebra, ^called 

 the COMMON ILIAC ARTERIES ; these diverge, and divide, 

 opposite the union of the sacrum with the os innominatum, 

 into external and internal iliac arteries ; the former courses 

 along the brim of the pelvis to pass out beneath Poupart's 

 ligament, and become the artery of the lower extremity ; 

 the latter dips into the pelvis to supply the viscera it con- 

 tains. In negroes and in old subjects, the common and 

 external iliac arteries are often curved and tortuous. 

 Lymphatic glands will be found along their course. 



At the point of the aorta's bifurcation a small artery 

 arises called the SACRA MEDIA; it descends on the mid- 

 dle line of the sacrum, giving off short branches upon 

 either side in its course toward the coccyx, where it termi- 

 nates. It sometimes arises from the left common iliac. 



The lumbar ganglia, forming part of the continuous chain 

 of the ganglia of the sympathetic, which extends from the 

 head to the coccyx, should now be dissected ; their con- 

 nection with the anterior branches of the spinal nerves can 

 also be traced. The ganglia will be found much larger in 

 size than those in the thoracic region ; they also lie closer 

 together; upon the right side they are covered in by the 

 vena cava, on the left they rest upon the vertebrae along 

 the edge of the psoas muscle. The branches which com- 

 municate with the anterior spinal nerves are of consider- 

 able length and accompany the lumbar arteries, passing 

 beneath the tendinous fibres by which the psoas muscle 

 arises. 



* These ganglia give origin to the h3 T pogastric plexus, 

 which lies upon the anterior surface of the sacrum and 

 last lumbar vertebrae, and distributes its branches to the 

 viscera of the pelvis. 



The LUMBAR ARTERIES are four in number, and corre- 

 spond to the intercostal branches of the thoracic aorta. 

 16 



