206 



THE FROG— THE PLATANA 



dorsal surface of the main branch of the sciatic nerve, note the iliac artery, and 

 also the sciatic vein alongside the semimembranosus nerve. 



Now lay the Frog on its back, and trace the femoral and the sciatic veins 

 forward. Note that these vessels join together a short distance behind the 

 posterior end of the kidney to form the renal portal vein, which extends along 

 the outer side of each kidney. Opposite the kidney the renal portal is joined 

 by the dorso-lumbar vein, which drains the blood from the back and the linnbar 

 region. 



Just anterior to the point of insertion of the vastus intemus muscle the 

 femoral vein gives rise to the pelvic vein, which runs over the anterior end of the 

 sartorius muscle and joins its fellow in the middle line to form the abdominal 

 vein, already noted in the first day's work. 



[In the Platana the femoral vein lies on the surface of the leg between the vastus 

 externus and the semimembranosus muscles. Trace the femoral vein bach along 

 the leg. Carefully separate the biceps muscle from, the semimembranosus, and 

 expose the sciatic nerve. This nerve also branches into two, as in the Frog. Follow- 

 ing the dorsal surface of the main branch, note the iliac artery ; and, on the ventral 

 surface of this nerve, note the sciatic vein. The smaller branch of the sciatic nerve 

 appears to run under the semimembranosus muscle to supply the rectus intemus 

 minor muscle. Just anterior to the origin of that nerve, the sciatic vein joins the 

 femoral vein to form the renal portal vein which passes forwards to the kidney. A 

 short distance anterior to its origin, the renal portal gives rise to a pelvic vein which 



1 1— Abdominal 



Pelvic 



- -Sciatic 



-Semimembranosus 

 nerve 



" ! 



I I '/ £ ' Abdominal 



Semimembranosus 

 nerve 



-Femoral 



Peroneal ner ve - 



Peroneal artery 



Peroneal artery 



Fiu. 71. — A. Dissection of the Leg of Bana ; and B, of XeiiopvM, from the dorsal surface, 

 showing the veins and arteries and the sciatic nerve. 



