COMPARATIVE ANATOMY OF THE CIRCULATORY SYSTEM 243 



to a group of nerves (brachial plexus) and somewhat concealed by arteries which 

 should not be injured. As the brachial vein it emerges from the wing and then 

 receives a branch from the shoulder muscles. The jugular vein passes anteriorly 

 on the dorsal side of the large arteries. On tracing the jugular forward it will 

 be found to receive the following veins, named in order from the heart forward: 

 on the medial side some small and then a large branch from the crop (at the point 

 of entrance of these into the jugular is situated a small reddish body, the cervical 

 lymph gland)-, on the lateral side a vein from the ^shoulder, and at the same 

 level, the vertebral vein from the vertebral column; medially, another branch 

 from the crop; laterally a large vein from a plexus of blood vessels in the skin of 

 the neck r then small veins from the esophagus and trachea. On freeing the 

 anterior end of the esophagus (also trachea) and cutting across it, the jugular 

 vein can be followed to the soft palate, where it joins its fellow of the opposite 

 side. Posterior to this union each receives a plexus of veins from the skin of 

 the face. On dissecting away the soft palate from the anastomosis of the two 

 jugular veins, branches from the skull will be found passing into the anastomosis. 



Draw the branches of the precaval vein as far as found. 



b) The postcaval vein: Raise the ventricles of the heart and note once more 

 the large postcaval vein emerging from the liver and entering the right auricle 

 between the two precaval veins. Note the large hepatic veins which it receives 

 from the liver. The left one of these hepatic veins receives the small vein of 

 the falciform ligament mentioned previously. Follow the postcaval vein into 

 the peritoneal cavity, turning all of the viscera to the left. The postcaval will 

 be picked up again at the posterior margin of the right lobe of the liver in contact 

 with the dorsal body wall. The postcaval is here seen to be formed by the union 

 of two veins, the iliac veins. In males the two oval testes will be noted at this 

 point of junction. In females the single ovary and oviduct will be noted to the 

 left, concealing the left iliac vein. Each iliac runs along the ventral face of a 

 three-lobed organ, the kidney, which is set close against the dorsal body wall. 

 Follow the right iliac vein. From between the first and second lobes of the 

 kidney it receives the large femoral vein, emerging from the leg. The femoral 

 vein receives a small branch from the body wall. Posterior to the entrance of 

 the femoral vein the iliac vein corresponds to the renal portal vein of reptiles and 

 Amphibia and may be so named. From between the second and third lobes of 

 the kidney it receives the sciatic vein which also comes from the thigh. At the 

 posterior end of the kidneys the two renal portal veins have an anastomosis with 

 each other. From this anastomosis rises the inferior mesenteric vein, already 

 noted as a branch of the hepatic portal system. It runs in the mesorectum. The 

 anastomosis of the renal portals also receives in the median line a small caudal 

 vein from the tail and on each side an internal iliac vein from the roof of the 

 pelvic region. The left iliac and renal portal veins are the same as the right, 

 except that in the female the left veins receive genital veins from the ovary and 



