58 LABOR A TOR Y G UIDE JN PHYS1OLOG Y. 



into the tibia, taking care not to injure any of the 

 neighboring tissues. Sever the tendon. Grasp its 

 free end, lift the biceps up, carefully cutting the 

 delicate connective tissue which joins it to neigh- 

 boring structures; sever its heads. The removal of 

 the biceps and a separation of the cleft which the 

 biceps occupied reveals three blood vessels and the 

 large trunk of the sciatic nerve. Which of the blood 

 vessels is the sciatic artery? Which the sciatic 

 vein? Which the femoral vein? 



Grasp and lift up the posterior end of the urostyle, 

 sever the ilio-coccygeal muscles, remove the urostyle. 



The sciatic plexuses formed by the 7th, 8th and 

 9th pairs of spinal nerves will be revealed. 



(4) Pass a glass nerve hook under the sciatic nerve, 

 gently lift it up, severing, with the scissors, the con- 

 nective tissue. The pyriformis muscle must also 

 be divided. The whole length of the sciatic nerve 

 may thus be readily dissected out. Care should be 

 taken not to stretch, pinch or cut the nerve during 

 this process. Lay the nerve upon the gastrocne- 

 mius muscle. 



(5) Grasp the triceps femoris muscle, pass a blade of 

 the scissors under its tendon; sever, and remove 

 the whole mass of muscles anterior to the femur. 

 In a similar manner remove the muscles posterior 

 to the femur. 



(6) Grasp the tendo achillis, sever low down at X; 

 lift up the gastrocnemius, sever the tibia and its 

 associated muscles as near to the knee joint as 

 possible. 



(7) Sever the femur at the juncture of its middle and 

 upper thirds. The finished preparation has the 

 characteristics shown in Fig. 11 B. A segment of 

 the vertebral column may or may not be left on. 



